Volume II: Detailed

Tables and Survey

Methodology

Community Water

System Survey

2000
Office of Water (4607M)

EPA 815-R-02-005B

December 2002

www.epa.gov/safewater

Printed on Recycled Paper

Photo by Brian Rourke

Cover Photo: Bangor, Maine Water District Thomas Hill Standpipe. Designed by

Ashley B. Tower of Tower and Wallace of New York and Holyoke, MA, the standpipe

was built during 1897 by Major James M. Davis on land once owned by the Thomas

brothers.

The standpipe is actually two structures: a 1.75 million gallon riveted steel tank

enclosed by a 110-foot tall wooden jacket. The tank itself is 75 feet in diameter and 50

feet tall. It is topped by a “carousel,” a three-ton steel drum from which 24 iron trusses

reach to the sides of the building.

The wooden jacket is 85 feet in diameter. It consists of twenty-four 1-foot x 1-foot x

48-foot hard pine main posts covered by 42,000 board-feet of hard pine and 220,000

cedar shingles. The jacket sits atop a stone foundation 9 feet high and 3 1/2 feet thick.

A 100-step winding staircase leads to the 12-foot wide promenade deck overlooking

the City of Bangor and surrounding communities.

The standpipe is topped by a 38-foot high flagpole and a railing consisting of 192

banisters that give it the look of a large wedding cake or crown when lit at night. The

entire structure was built in just 6 months.

Listed on the National Register of Historic Places and designated as an American

Water Works Landmark, the standpipe continues to store water and regulate water

pressure for Bangor’s downtown.
i

Table of Contents

List of Tables ................................................................. ii

Part 1: Detailed Survey Results ..................................................... 1

Interpreting the Survey Results ............................................... 3

Notes on Interpreting the Detailed Tables ....................................... 5

Detailed Tables ......................................................... 11

Part 2: Methodology Report ..................................................... 115

1. Introduction ........................................................ 117

2. Sample Design and Weighting ........................................... 120

3. Survey Design and Response ............................................ 137

4. Quality Assurance and Peer Review ...................................... 148

Appendix A: Community Water System Survey Questionnaire ..................... 159
ii

List of Tables

(Tables are by primary source of water and system service population, unless otherwise noted.)

Table Description

Table 1 Crosswalk from SDWIS to CWSS 2000 Sample

Table 2 Number and Percentages of Systems

Table 3 Number of Systems by Ownership and Primary Source of Water

Table 4 Average Daily Production

Table 5 Unaccounted for Water by Ownership

Table 6 Average Number of Wells

Table 7 Average Number of Entry Points to the Distribution System

Table 8 Number of Systems Selling to Other Public Water Suppliers

Table 9 Water Systems Not Providing Any Treatment

Table 10 Ground Water Entry Points Not Receiving Treatment

Table 11 Treatment Plants per System

Table 12 Number of Wells Treated per Treatment Plant

Table 13 Treatment Plant Flow Characteristics

Table 14 Ratio of Daily Treated Production to Design Capacity for Plants

Table 15 Treatment Plants and Operator Hours per Week by Population

Table 16 Treatment Plants and Operator Hours per Week by Daily Flow

Table 17 Plants Lacking 24/7 Operator that Have SCADA Systems by Population

Table 18 Systems Lacking 24/7 Operator that Have SCADA Systems by Daily Flow 

Table 19 Treatment Objectives by Population

Table 20 Treatment Objectives by Daily Flow

Table 21 Treatment Schemes by Population

Table 22 Treatment Schemes by Daily Flow

Table 23 Treatment Practices for Surface Water Plants by Population

Table 24 Treatment Practices for Ground Water Plants by Population

Table 25 Treatment Practices for Surface Water Plants by Daily Flow

Table 26 Treatment Practices for Ground Water Plants by Daily Flow

Table 27 Contaminants in Very Large Ground Water and Surface Water Systems

Table 28 Contaminants in Very Large Water Systems

Table 29 Plants Using Residual Management Process Options by Population
Table Description

iii

Table 30 Plants Using Residual Management Process Options by Daily Flow

Table 31 Plants With Specific Discharge Options by Population

Table 32 Plants With Specific Discharge Options by Daily Flow

Table 33 Treated-Water Storage Information

Table 34 Average Capacity Treated-Water Storage Information

Table 35 Pipe Distribution Summary by Ownership

Table 36 Average Size of Pipe in Distribution System by Ownership

Table 37 Percentage of Pipe in Each Age Categoryby Source

Table 38 Percentage of Pipe in Each Age Category by Ownership

Table 39 Service Connections Profile by Ownership

Table 40 Population Served by Ownership

Table 41 Annual Deliveries per Customer Service Connection by Ownership

Table 42 Cross Connection Control Programs by Ownership

Table 43 Cross Connection Control Program Information by Ownership

Table 44 Elements of Cross Connection Control Programs by Population

Table 45 Backflow Prevention Assemblies that Fail Annually by Ownership

Table 46 Total Revenue by Source

Table 47 Total Revenue by Ownership

Table 48 Total Revenues by Type of Private System

Table 49 Revenue if Reporting Positive Revenue and Expenses by Ownership

Table 50 Systems with Each Type of Revenue Source by Ownership

Table 51 Percentage Received From Each Type of Revenue Source by Ownership

Table 52 Percentage of Revenue from Each Customer Category by Ownership

Table 53 Total Revenue in Dollars per Thousand Gallons Sold by Ownership

Table 54 Water Sales Revenue by Ownership

Table 55 Customer Breakdown of Water Sales Revenue by Ownership

Table 56 Residential Revenue per Connection by Ownership

Table 57 Residential Revenue per Connection by Type of Private System

Table 58 Residential Rate Structure and Billing Profile by Ownership

Table 59 Total Expenses by Source

Table 60 Total Expenses by Ownership

Table 61 Expenses if Reporting Positive Revenue and Expenses by Ownership
Table Description

iv

Table 62 Expense Breakdown by Major Categories by Ownership

Table 63 Total Expenses in Dollars per 1000 Gallons Produced by Source

Table 64 Total Expenses in Dollars per 1000 Gallons Produced by Ownership

Table 65 Ratio of Total Revenue to Total Expenses by Ownership

Table 66 Ratio of Total Revenue to Total Expenses by Private Systems

Table 67 Number of Employees and Annual Labor Costs by Source

Table 68 Number of Employees and Annual Labor Costs by Ownership

Table 69 Major Capital Improvements in the Past 5 Years by Source

Table 70 Major Capital Improvements in the Past 5 Years by Ownership

Table 71 Total Capital Investment in the Past 5 Years by Source

Table 72 Total Capital Investment in the Past 5 Years by Ownership

Table 73 Type of Capital Expense in the Past 5 Years

Table 74 Capital Expense in the Past 5 Years

Table 75 Allocation to Each Type of Capital Expenses in the Past 5 Years

Table 76 Systems Investing Capital Funds in Each Category by Ownership

Table 77 Capital Funds Invested in the Past 5 years by Ownership

Table 78 Amount Capital Funds Invested by Ownership

Table 79 Source of Capital Funds in the Past 5 Years by Ownership

Table 80 Source of Capital Funds in the Past 5 Years by Ownership and System

Table 81 Amount of Capital Funds Acquired From Each Source by Ownership

Table 82 Average Interest Rate for Capital Funds Lending Sources by Ownership
1

Part 1

Detailed Survey Results
2
3

INTERPRETING THE SURVEY RESULTS

This volume presents extensive and detailed tabulations of the wide variety of data collected by

the survey. The tables in this volume summarize the survey results at very fine levels, breaking out the

data by eight different population size categories of water systems, and then further breaking out each

size category by other system characteristics, such as type of ownership or primary water source.

The report consists of 82 tables that summarize the data, many of which include confidence

intervals for each calculation presented. In these tables, each confidence interval appears immediately

below the calculation to which it applies. Please familiarize yourself with the interpretive notes when

you review the tables themselves. 

The tabulations presented in this report are based on data collected from a sample of U.S.

water systems, not from a census of every water system in the United States. A confidence interval is

one way to gauge how precisely a given tabulation of survey data can be generalized to the entirety of

U.S. systems represented by the surveyed systems. Any result presented in a table must be viewed as

the center of a range that would encompass the precise number that would be found if every U.S. water

system could have been included in the tabulation, and not only those who were sampled and

responded to the survey. The confidence interval expresses this range as a “plus/minus,” that is, as an

amount to be added to and subtracted from the calculated data point actually presented in the table. 

The size of the confidence interval is designed to include the true value in the stated range 95 percent of

the time; i.e., if we drew repeated samples and produced the confidence interval for each sample, the

interval would include the true value 95 percent of the time. 

For example, Table 60 shows as a survey result that the average publicly owned water system

serving over 500,000 people has annual expenses of $131.5 million. The table also shows the

confidence interval for this estimate to be ±$23.7 million. Thus, based on the sample of water systems,

we can be 95 percent certain that the average annual per capita expenses of all publicly owned systems

serving populations of over 500,000 is between $107.8 million and $155.2. million.

These tables always express the confidence interval in the same units as the calculation to which

it applies. Thus, in Table 4 the confidence interval numbers for average daily water production

represent the same units as the base calculation, namely, millions of gallons per day. In the same table,

the confidence interval numbers for the percentage of production derived from different water sources

are themselves expressed as percentages. In all cases, the confidence interval may be directly added to

and subtracted from the corresponding calculation to determine the expected range.

These tables serve as a starting point for detailed analyses of the data. As shown in Volume I,

and as will be apparent in many of the tables in this volume, water systems are a diverse group. While

the mean or medians as measures of central tendency may be appropriate statistics in some cases, in

others further detail will be required. As described in the notes below, outliers were dropped from
4

some of the tables to produce meaningful estimates of “typical” systems. Additional adjustments may

be necessary to support other analyses. Some analyses may require the use of percentiles or other

measures of the full distribution of the data. Other analyses may require excluding the tails of the

distribution to characterize typical systems. EPA will continue to analyze the data and present results to

support its various regulatory and policy development and implementation analyses. 

Finally, several of the tables reports results for water systems’ treatment plants and facilities. 

For this report, a treatment plant or facility is any location where the water system takes steps to

change the quality of the water. It includes standard facilities that are clearly recognized as treatment

plants, such as conventional filtration plants. It also includes smaller facilities that may not be

considered treatment plants in other contexts; for example, a chemical feed on a well that adds chlorine

to the water is considered a treatment facility in this report. There is one exception to the general rule

that all points where the system makes changes to the water is a treatment facility. Systems that

purchase water may boost disinfection or adjust pH within their distribution system; these sites are not

counted as treatment facilities.
5

Detailed Survey Result Tables

Notes on Interpreting the Detailed Tables

1. Weighted data. The survey results presented in the following tables are all based on weighted

data. As described in Chapter 2 of the methodology report, each water system contained in

the final survey database was assigned a sample weight. These weights reflect the fact that the

data come from a statistically representative sample of water systems, rather than from a census

of every water system in the U.S. In effect, each sampled system represents some number of

similar systems from the entire population of U.S. water systems; the number of systems so

represented is equal to the sample weight. When added up, the weights of all systems in the

final sample will equal the total number of U.S. Community Water Systems that meet the

eligibility definition used for the survey (e.g., Federal and state-owned systems were not

included). Thus, for the tables to validly represent all eligible U.S. water systems, it is

necessary to incorporate each system’s sample weight as an additional factor in each

calculation involving a data item reported by that system. Another way of expressing this is to

say that, when tabulating the data, each sampled system counts not just once as itself, but

counts as many times as the numerical amount of its weight. See section 2.2 for a detailed

discussion of the derivation of the sample weights. 

2. Interpretation of Table Results. Each result presented in the tables is the weighted average

of the particular data item, for the group of water systems characterized by the row and column

headings labeling the table cell where the results appears. The survey data are tabulated so as

to facilitate analysis of water systems. In general, this means that the report tabulates all

summary results by calculating a given item for each system, factoring into that result the

system’s sampling weight, then presenting the mean of the weighted results for all the systems

falling into the respective table categories (as defined by the table row and column headings). 

This has significant implications when the calculation of a specific item requires deriving the

result from two or more survey variables, e.g., a ratio or a percentage breakdown of

component amounts within a total amount. For example, in the case of a ratio, the reported

result is the average (mean) of the ratios for each system, rather than the ratio of average values

for each of the two variables across systems. This approach treats every system in the universe

equally, implying that characteristics of the system are the primary unit of analysis. The alternate

approach would treat the content of the component variables in each table as the unit of

analysis.

By way of example, consider two systems. One system produces 1,000,000 gallons per day,

and 400,000 of those come from ground sources; hence, 40% of the system’s water comes

from ground sources. The other system produces 2,000,0000 gallons per day and 1,600,000

of those come from ground sources; hence, 80% of the systems water comes from ground

sources. The CWS Survey report would show a result that, on average, these two systems
6

produce 60% of their water from ground sources: (40%+80%)÷ 2. If the alternate approach

where chosen, gallons would be the unit of analysis, and the calculation would show that 67%

of the water in those systems comes from ground sources:

(400,000+1,600,000)÷(1,000,000+2,000,000). (To focus clearly on the point being

illustrated, this example does not attempt to demonstrate the further effect that the system

sample weights have on the actual calculations.)

The report has adopted the former approach because this initial view of the data is intended

primarily as an analysis of system-level characteristics. There are some exceptions to this

approach. Table 11 presents data on both level of the system and a water treatment plant

(many systems have more than one treatment plant, while some facilities have none). Tables

12-26 and 29-32 present data on the level of a treatment plant. Tables 27 and 28 present data

for test points within systems. Tables 37 and 38 present data on the amount of pipe in the

nation, rather than on the system level. Tables 75, 78, and 81 present data on the share of

capital funds in the nation, rather than system averages. 

3. Percentages summing to 100%. Some percentage tables may not present results that total

to 100%, as would ordinarily be expected. Such tables would be among those that present

absolute or percentage breakdowns of the whole into its components, e.g., breakdowns of total

revenue into different customer categories, such as Table 51. Logically, in such breakdowns,

the line item amounts should sum to the total amount, and line item percentages should sum to

100 percent. However, in some instances, the tabulated results may not sum exactly to the

whole. To increase the precision of each individual result, each component line item was

calculated separately using all the data available for the line item. Due to differential item

non-response, some component variables may actually have more or fewer observations

available than other components. While including all available data in the calculation of the

component increases the precision of the tabulated result for the component, it can cause a

small reduction in consistency across components, since slightly different systems may be

represented in the different calculations. EPA and the CWS survey analysts decided that the

increased accuracy for each item outweighs the slight reduction in consistency. 

In a few tables, a series of percentages may validly sum to greater than 100%. This occurs

when more than one item may apply to the same system. For example, treatment plants may

have more than one treatment objective, so the percentage of plants with each objective will

sum to more than 100 percent. This situation is always noted on the table. 

4. Confidence Intervals. The size of the confidence interval is designed to include the true value

in the stated range 95 percent of the time. Each confidence interval presented in Part 2 is

based on the assumption that the average value reported in a given table cell is normally

distributed. In general, this assumption is true. However, calculations based on small numbers

of systems may violate this assumption. In such cases the reported confidence intervals will not
7

be correct. Most of these can be identified by noticing when the plus/minus confidence interval

width is larger than, or almost as large as, the calculated average itself. To compute correct

confidence intervals for such situations requires examination of the empirical distributions for

each variable in the tabulation and is beyond the scope of this report.

Because of the foregoing issue, the reader should take note of results where the lower end of

the confidence interval is below zero, as negative numbers are not meaningful in any of the

tabulations presented in this report. Similarly, for calculations of percentages, high ends of

ranges above 100% are not meaningful. While the reader should be on the lookout for these

conditions when any number is near zero or any percentage is near 100%, they can occur at

other times, particularly when the confidence interval is large. As stated in note 3, a series of

percentages may validly sum to greater than 100% in some tables, when more than one item

may apply to the same system. This situation is not related to the issue of confidence intervals

extending an individual percentage beyond 100%.

5. Treatment of outliers. For several of the tables, one or two observations have values well

above the mean or even the 90th percentile. These outliers would tend to distort the estimates

presented in the table and would lead to a misrepresentation of the central tendency for the

characteristics in question. For example, 3 systems serving greater than 500,000 people in the

sample have more than 100 entry points to the distribution system from ground water sources. 

Other systems of similar size, on average, have 14 entry points from ground water. If the three

outliers are included, the average number of entry points is over 65. 

In cases like this, the outliers are dropped from the analysis. It is noted at the bottom of the

table when outliers are dropped. The note also will show how the exclusion of the outliers

affect the estimate, 

6. Interpretation of blank cells and cells with calculated results of zero.

Empty Cells: Throughout the tables, some individual cells or blocks of continuous cells have

an asterisk, to denote the cell does not contain an estimate. Any empty cell or block of cells

means that there were no observations with data for the cell(s) in question. Generally, this

occurs for one of three reasons.

C There are no systems in the cell. The most common illustration of this occurs in all

tables that break out the data by ownership type. When data are reported for ancillary

systems, the cells for the systems serving more than 3,300 people are always blank for

ancillary systems, since there are no ancillary systems in these size categories.

C The item does not apply to the group of systems belonging to that cell. For example, in

table 82, the cell SRF loans for private systems serving 100 or fewer people is empty. 
8

This is because no private systems of this size made use of SRF loans. 

C The item applies to the group of systems belonging to the cell, but no systems provided

data for the item (sometimes referred to as “missing data” in terms of the analytical data

file and as “item non-response” in terms of the data collection process that led to the

final data file). For example, in Table 13, none of the mixed-water treatment plants in

systems serving 25-100 customers provided data on their flows, so these cells are

empty on the table.

It is not always possible to distinguish between the last two reasons from the information

available in the table. Sometimes the reason is apparent for the table itself. Often, however,

further analysis of the database would be needed to determine which particular reason is the

basis for a blank cell.

Zero Results: In discussing Table 82 above, it was noted that certain cells are blank for

customer categories of private systems. However, other tables have cells which specifically

report a zero result and are zero instead of blank. This illustrates an important distinction when

interpreting the tables. Blank cells and cells reporting a zero result are not the same thing, and

should not be interpreted as such. A reported result of zero means that data were available to

produce a calculation, and the calculation resulted in zero. 

It should also be noted that occasionally a report of a zero result is a function of the level of

precision chosen as appropriate for presenting the data in a given table. In a few instances,

items appearing as zero results are actually very small numbers that round to zero within the

precision limits of the respective table.

7. Observations. The term “observations” refers to the actual number of sampled water systems

that provided data for a given tabulated item. Some tables present the number of observations

on which the tabulated results are based. In these as in all the tables, the results are still based

on the weighted data, not on the simple means of the unweighted observations. The report of

the number of observations can be used as a very approximate indication of the sampling

precision of the tabulated result. Results based on a small number of observations may not be

precise estimates of the universe of water systems represented by the sampling systems. They

are included because they may be useful indicators of areas worth further investigation.

8. Individual table notes. Additional specific notes and definitions appear on individual tables. 

The specific CWS Survey questionnaire item(s) on which each tabulation is based are cited

below the table. The citation refers to the corresponding question number(s) on the CWS

Survey mail questionnaire, which can be found in this report as an Appendix to the

Methodology Report. The citations are in the format “Q.#;” the question numbering is identical

in both questionnaire versions.
9

9. Variables for row and column headings. In addition to the data sources for the specific

tabulations, several data items are used repeatedly throughout the tables as the break-out

variables for the table row and column headings. Their sources are not cited on the

individual tables. These items and their data sources are 

C Population served , from question 20. (If data were not reported in the survey, the

population data from SDWIS are used. 

C Water source, from question 7. 

C Ownership, from questions 3 and 4. Note: for the sake of brevity in the table

headings, privately owned community water systems are labeled as “Private

Systems” and publicly owned community water systems are labeled as “Public

Systems.” This use of the label “Public Systems” should not be confused with the

CFR definitional term Public Water System, which is a broad class of water

systems providing the public with piped drinking water for human consumption. 

A Community Water System means a public water system which serves at least

15 service connections used by year-round residents or regularly serves at least 25

year-round residents. (40 CFR 141.2)

C Treatment facility flow, from question 12. 

For population served and water source, data from SDWIS are used if the system did not

provide the data in the survey. Approximately 10 percent of the sample were assigned

population data from SDWIS because of missing or incomplete responses to the

population served questions. An additional 5 percent were assigned source data from

SDWIS. 

10. Estimate of the number of systems in the nation. The report provides an estimate of

the national number of community water systems, 52,186. This estimates is a weighted

estimate based on sample, and is slightly different from the count of systems in the first

quarter of 2002 SDWIS database. The total count is 166 lower than in SDWIS; the count

of systems by source and population served is different as well. Table 1 of this Volume

presents a detailed crosswalk from count of systems in the latest SDWIS database and the

estimate based on the 2000 CWS Survey. The differences between the SDWIS counts

and the CWSS estimate can be divided into 5 groups. 

First the latest SDWIS draw is a snapshot of systems in 2002. The survey describes

systems as they existed in 2000. The data used for the frame for the survey was drawn in

1998; this frame had approximately 3,700 fewer systems in it then the 2002 SDWIS. 

Second, to prepare for the survey (and the 1999 Drinking Water Infrastructure Needs

Survey, DWINS, which used the same frame), the states conducted a thorough review of

the database. As part of the states’ review the population of consecutive systems were

adjusted to account for the total number of people served by each system. While SDWIS
10

includes only direct retail populations in its estimate of each systems’ population-served,

the CWS Survey classifies systems by the total population they serve. Also, several

major cities had multiple records in SDWIS; independent of the states’ review, the

multiple records were removed from the data base and replaced with a single record. 

The net result of this step adds 4,800 systems to the database; it also moves several

systems across population served categories. 

The third step adjusts for inactive systems. As part of the data collection effort, several

systems in the sample were not active water systems. In some cases, they merged with

other systems; in other cases, they were no longer community water systems (e.g., they

were no longer in business, or they served fewer than 25 people or 15 connections at least

6 months of the year). In these cases, steps were taken to confirm the status of the

systems. For example, site visitors went to the system to confirm its status. 

Approximately 1,200 systems were dropped from the inventory for this reason. 

The remaining two changes do not affect the total count of systems; rather, they affect the

number of systems classified as ground, surface, or purchased, and they affect the

number of systems in each population-served category. SDWIS uses a hierarchy to

classify systems by source; basically, a system is classified as a surface water system if it

uses any surface water. The survey classifies systems by its primary source of water; a

system is classified as a surface water system if surface water is its largest source. It is a

ground water system if its largest source is ground water. It is a purchased system

otherwise. The systems’ responses to the survey are used to classify their source. The

final adjustment changes the population-served based on the reported population in the

survey.

11. Use of the terms expenses and expenditures. Systems use the terms expenses or

expenditures to refer to their spending. Private systems generally use the term

“expenses” in accounting as a term for the spending done by a system. Public systems

refer to spending as “expenditures”; they reserve the term “expense” for when a cost is

incurred, and use the term “expenditure” for when the spending takes place. Tables 49,

59-66, and 73-78 use the term expenses to report spending by both public and private

systems. 
Table 1

Crosswalk from SDWIS to CWSS 2000 Sample

Universe of Systems

SDWIS CWSS Projected Universe CW

Classification 123456 Sam

Year data represents 2002 2000 2000 2000 2000 2000 2Adjust for state review, and consecutive and grouped systems No No Yes Yes Yes Yes Adjust for inactive systems No No No Yes Yes Yes Adjust water source definition No No No No Yes Yes Adjust population served No No No No No Yes Water source System Service PopulationGround water 25 - 100 12,838 13,073 13,901 12,740 12,713 11,756 

101 - 500 13,238 12,329 13,960 12,894 12,845 13,145 501 - 3,300 9,367 8,933 9,459 9,069 8,960 8,970 3,301 - 10,000 2,368 2,126 2,348 2,333 2,557 3,071 10,001 - 50,000 1,211 1,019 1,221 1,274 1,296 1,340 50,001 - 100,000 136 94 157 149 138 136 100,001 - 500,000 55 42 68 72 68 161 Over 500,000 6 6 12 18 12 10 

Surface water 25 - 100 417 386 396 827 823 833 

101 - 500 635 437 688 1,150 1,150 1,136 501 - 3,300 1,450 1,245 1,479 1,355 1,351 1,212 3,301 - 10,000 998 834 970 1,040 964 1,008 10,001 - 50,000 921 791 930 941 918 988 50,001 - 100,000 191 150 209 202 190 210 100,001 - 500,000 172 144 189 191 168 178 Over 500,000 38 29 65 59 54 53 

Purchased water 25 - 100 1,028 867 776 679 710 69 

101 - 500 2,176 1,840 1,972 2,030 2,079 2,180 501 - 3,300 3,059 2,678 2,815 3,441 3,553 3,834 3,301 - 10,000 1,049 886 925 894 746 973 10,001 - 50,000 773 590 678 650 652 685 50,001 - 100,000 121 76 101 119 142 125 100,001 - 500,000 67 31 58 53 80 92 Over 500,000 5 2 5 6 17 21 

Total 52,319 48,608 53,382 52,186 52,186 52,186 1Notes: For a more detailed discussion, refer to Note 10 in the introduction to the tables.

Each column represents the following:

1: Current SDWIS universe2: Unadjusted SDWIS universe when CWSS sample was drawn.3: Adjusted SDWIS universe when CWSS sample was drawn.4-6: CWSS projected Universe.

Classification 3 served as the sample frame. (The frame did not separate purchased systems.)The universe of systems for classifications 4-6 are estimates, based on the sample.

(Continued)

11 
Table 1 (Cont.)

Crosswalk from SDWIS to CWSS 2000 Sample

Classification definitions

Year

2002 Represents the count of systems in the fourth quarter of 20012000 Represents the number of systems in the inventory in 2000. 

State Review

The States reviewed the inventory for the 1999 Drinking Water Infrastructure Needs Survey. 

Consecutive systems

SDWIS counts the population served directly by the water system as the population served by the system. In consecutivesystems, only the retail population is counted -- customers served by systems who purchase the water from the wholesaler are not include in the wholesaler's population served. The adjustment counts the wholesale and retail population as part ofthe population served. This adjustment was made by the states as part of their review of their inventories.

Amalgamated systems

Some systems contain more than one PWSID in SDWIS and are therefore counted as multiple systems. These systems are counted as a single system for the survey.

Inactive systems

Some systems in SDWIS are no longer active community water systems. Others have been combined with existing systems. These inactive systems are dropped from the inventory.

Water Source

SDWIS classifies water systems as surface water if they contain any surface water sources. CWSS classifies systems by the primary source of water -- i.e., the source that provides most of the system's water.

Population served

The population served in SDWIS is as reported, adjusted for consecutive systems. The population served is adjusted for thesystems' responses to the survey. 

12 
Table 2

Number and Percentage of Systems

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

100% Ground Water

Number 10,358 12,521 8,687 2,576 971 80 108 Percent 82 76 62 51 32 17 25 

Mostly Ground Water

Number 1,398 624 283 495 368 56 53 Percent 11 4 2 10 12 12 12 

Primarily Surface Water Systems

100% Surface Water

Number 790 897 1,015 835 769 140 113 Percent 6 5 7 17 26 30 26 

Mostly Surface Water

Number 43 239 197 173 220 70 65 Percent 0 1 1 3 7 15 15 

Primarily Purchased Water Systems

100% Purchased Water

Number 69 2,050 3,412 773 476 94 46 Percent 1 12 24 15 16 20 11 

Mostly Purchased Water

Number * 130 423 200 209 31 45 Percent * 1 3 4 7 7 10 

All

Number 12,658 16,461 14,017 5,052 3,013 471 430 Percent 100 100 100 100 100 100 100 

Data: Q.7Notes: * No purchased water systems of this size in sample.

13 
Table 3

Number of Systems

By Ownership and Primary Source of Water

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public

Primarily Ground Water Systems 489 3,556 6,694 2,560 1,080 124 143 Primarily Surface Water Systems 245 683 1,139 935 894 182 162 Primarily Purchased Water Systems * 1,513 3,449 819 568 109 89 

All Public 734 5,752 11,282 4,314 2,542 415 394 

Private

Primarily Ground Water Systems 11,267 9,590 2,276 511 259 12 17 Primarily Surface Water Systems 588 453 73 73 95 28 16 Primarily Purchased Water Systems 69 666 386 154 117 16 3 

All Private 11,924 10,709 2,735 738 471 56 36 

All 

Primarily Ground Water Systems 11,756 13,146 8,970 3,071 1,339 136 160 Primarily Surface Water Systems 833 1,136 1,212 1,008 989 210 178 Primarily Purchased Water Systems 69 2,179 3,835 973 685 125 92 

All 12,658 16,461 14,017 5,052 3,013 471 430 

Data: Q.3, Q.7Notes: * No purchased water systems of this size in sample.

14 
Table 4

Average Daily Production (MGD)

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,0

500,0

Primarily Ground Water Systems

100% Ground Water 

Average Daily Production 0.011 0.034 0.158 1.053 2.628 11.892 17.6

Confidence interval +|- 0.009 +|- 0.009 +|- 0.034 +|- 0.193 +|- 0.382 +|- 1.643 +|- 13.1

Mostly Ground Water

Average Daily Production 0.003 0.019 0.524 0.872 3.718 11.225 29.7

Confidence interval +|- 0.004 +|- 0.000 +|- 0.552 +|- 0.365 +|- 1.154 +|- 1.490 +|- 4.3

% Ground Water 66.7 83.3 58.1 78.0 84.5 74.1 7

Confidence Interval +|- 0.0 +|- 0.0 +|- 4.9 +|- 11.1 +|- 9.3 +|- 3.6 +|- 

% Surface Water 0.0 0.0 41.9 7.4 2.1 12.4 

Confidence Interval +|- 0.0 +|- 0.0 +|- 4.9 +|- 7.3 +|- 3.9 +|- 6.1 +|- 3

% Purchased Water 33.3 16.7 0.0 14.7 13.4 13.5 2

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 9.6 +|- 8.8 +|- 6.4 +|- 

Observations 86 88 88 53 35 20 Primarily Surface Water Systems

100% Surface Water

Average Daily Production 0.010 0.071 0.279 0.935 4.766 11.041 31.8

Confidence interval +|- 0.007 +|- 0.031 +|- 0.059 +|- 0.153 +|- 1.430 +|- 2.681 +|- 2.7

Mostly Surface Water

Average Daily Production 0.014 0.013 0.269 0.779 4.253 11.537 42.4

Confidence interval +|- 0.012 +|- 0.010 +|- 0.141 +|- 0.318 +|- 1.325 +|- 1.682 +|- 5.0

% Ground Water 35.2 24.0 13.5 18.9 14.3 10.4 1

Confidence Interval +|- 19.6 +|- 6.5 +|- 10.3 +|- 10.6 +|- 6.5 +|- 4.7 +|- 2

% Surface Water 64.8 76.0 69.4 76.7 81.5 85.4 8

Confidence Interval +|- 19.6 +|- 6.5 +|- 8.0 +|- 8.5 +|- 5.8 +|- 5.0 +|- 3

% Purchased Water 0.0 0.0 17.0 4.4 4.1 4.3 

Confidence Interval +|- 0.0 +|- 0.0 +|- 13.0 +|- 4.4 +|- 4.3 +|- 3.4 +|- 

Observations 41 49 56 63 64 35 

15 
Table 4 (Cont.)

Average Daily Production (MGD)

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,0

500,0

Primarily Purchased Water Systems

100% Purchased Water

Average Daily Production 0.008 0.017 0.150 0.886 2.302 9.595 23.9

Confidence interval +|- 0.008 +|- 0.004 +|- 0.046 +|- 0.445 +|- 0.918 +|- 1.417 +|- 3.2

Mostly Purchased Water

Average Daily Production * 0.016 0.103 1.407 5.595 16.498 32.2

Confidence interval * +|- 0.000 +|- 0.093 +|- 0.490 +|- 1.969 +|- 8.407 +|- 4.6

% Ground Water * 33.3 42.8 28.4 12.8 22.4 1

Confidence Interval * +|- 0.0 +|- 4.6 +|- 10.9 +|- 7.3 +|- 10.8 +|- 4

% Surface Water * 0.0 0.0 3.9 6.9 8.1 

Confidence Interval * +|- 0.0 +|- 0.0 +|- 6.1 +|- 8.0 +|- 9.2 +|- 3

% Purchased Water * 66.7 57.2 67.7 80.3 69.5 7

Confidence Interval * +|- 0.0 +|- 4.6 +|- 9.7 +|- 10.3 +|- 7.2 +|- 4

Observations 6 22 47 19 17 22 All Systems

Average Daily Production 0.011 0.033 0.166 0.995 3.589 11.305 28.8

Confidence Interval +|- 0.008 +|- 0.007 +|- 0.024 +|- 0.131 +|- 0.518 +|- 1.093 +|- 5.4

Observations 138 166 208 170 159 116 2Data: Q.7Notes: * No purchased water systems of this size in sample.Definitions: Production is the amount of water drawn from each source. It includes water delivered to custom

16 
Table 5

Unaccounted for Water (MGD)

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300 3,301 - 10,000

10,001 - 

50,000

50,001 - 

100,000

100,

500

Public SystemsAverage Unaccounted for Water 0.003 0.001 0.017 0.113 0.296 1.166 2

Confidence Interval +|- 0.006 +|- 0.000 +|- 0.006 +|- 0.032 +|- 0.074 +|- 0.268 +|- 0.

% of Total Water Produced 1.140 5.990 9.935 11.562 8.528 9.693 6

Confidence Interval +|- 1.419 +|- 7.067 +|- 3.763 +|- 3.161 +|- 1.861 +|- 2.044 +|- 1.

Private SystemsAverage Unaccounted for Water 0.000 0.001 0.012 0.100 0.287 1.055 3

Confidence Interval +|- 0.000 +|- 0.000 +|- 0.009 +|- 0.061 +|- 0.110 +|- 0.395 +|- 0.

% of Total Water Produced 0.187 2.188 6.237 10.686 12.330 11.093 10

Confidence Interval +|- 0.269 +|- 2.660 +|- 3.940 +|- 4.252 +|- 4.511 +|- 4.317 +|- 2.

All SystemsAverage Unaccounted for Water 0.000 0.001 0.016 0.111 0.294 1.152 2

Confidence Interval +|- 0.000 +|- 0.000 +|- 0.006 +|- 0.028 +|- 0.064 +|- 0.238 +|- 0.

% of Total Water Produced 0.258 3.355 9.136 11.435 9.135 9.867 6

Confidence interval +|- 0.269 +|- 2.859 +|- 3.218 +|- 2.724 +|- 1.747 +|- 1.864 +|- 1.

Data: Q.5DDefinitions: Unaccounted for water includes system losses, water for fire suppression, and water used in th

17 
Table 6

Average Number of Wells

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Wells

Mean 1.4 1.9 2.6 4.1 7.8 18.1 20.5 Confidence interval +|- 0.1 +|- 0.2 +|- 0.4 +|- 0.7 +|- 1.5 +|- 3.6 +|- 10.1 

Median 1 2 2 4 7 18 19 

Observations 101 93 90 67 49 28 43 

Primarily Surface Water Systems

Wells

Mean 1.5 1.3 1.3 3.5 6.9 11.1 20.9 Confidence interval +|- 0.8 +|- 0.6 +|- 0.4 +|- 1.7 +|- 3.5 +|- 5.5 +|- 7.3 

Median 1 1 1 5 6 7 7 

Observations 2 5 6 9 11 16 33 

Primarily Purchased Water Systems

Wells

Mean * 1.0 1.5 3.7 5.2 15.9 16.6 Confidence interval * +|- 0.0 +|- 0.6 +|- 1.7 +|- 2.7 +|- 10.5 +|- 3.3 

Median * 1 2 3 4 9 15 

Observations * 1 3 6 11 6 22 

All Systems

Wells

Mean 1.4 1.9 2.5 4.1 7.4 16.2 19.9 Confidence interval +|- 0.1 +|- 0.2 +|- 0.4 +|- 0.6 +|- 1.3 +|- 3.2 +|- 6.4 

Median 1 2 2 4 6 12 15 

Observations 103 99 99 82 71 50 98 

Data: Q.10Notes: * No purchased water systems of this size in sample.

Excludes systems with zero wells.One surface water system serving 3,301-10,000 with 64 wells was dropped from the estimmean number of wells are 18.8 for this category.Drops 2 outliers from the over 500,000 population category, each with over 200 wells. If outhe average number of wells for ground water systems are 185 and surface water 49 for th

18 
Table 7

Average Number of Entry Points to the Distribution System

By Primary Source of Water

System Service Population Category

Primary Source of Water 

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Entry Points from Ground Water Sources 1.2 1.4 1.8 2.8 4.2 6.3 7.2 

Confidence interval +|- 0.1 +|- 0.2 +|- 0.3 +|- 0.4 +|- 1.1 +|- 2.1 +|- 4.0 

Entry Points from Surface Water Sources 0.1 0.1 0.0 0.1 0.1 0.9 0.1 

Confidence interval +|- 0.1 +|- 0.1 +|- 0.0 +|- 0.1 +|- 0.1 +|- 0.8 +|- 0.1 

Observations 104 93 92 67 50 29 43 

Primarily Surface Water Systems

Entry Points from Ground Water Sources 0.1 0.3 0.2 0.4 0.8 1.2 1.4 

Confidence interval +|- 0.1 +|- 0.3 +|- 0.1 +|- 0.4 +|- 0.7 +|- 1.3 +|- 0.5 

Entry Points from Surface Water Sources 1.3 1.2 1.1 1.2 1.3 1.6 1.6 

Confidence interval +|- 0.4 +|- 0.3 +|- 0.1 +|- 0.2 +|- 0.1 +|- 0.2 +|- 0.1 

Observations 46 55 69 76 83 58 109 

Primarily Purchased Water Systems

Entry Points from Ground Water Sources 0.0 0.1 0.2 0.3 1.1 2.6 4.5 

Confidence interval +|- 0.0 +|- 0.1 +|- 0.2 +|- 0.3 +|- 0.7 +|- 2.5 +|- 2.1 

Entry Points from Surface Water Sources 0.0 0.0 0.0 0.0 0.1 0.2 0.3 

Confidence interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.1 +|- 0.1 

Observations 6 23 50 27 28 30 48 

All Systems

Entry Points from Ground Water Sources 1.1 1.1 1.2 1.8 2.4 3.1 4.2 

Confidence interval +|- 0.1 +|- 0.2 +|- 0.0 +|- 0.0 +|- 0.6 +|- 1.1 +|- 1.2 

Entry Points from Surface Water Sources 0.2 0.1 0.1 0.3 0.5 1.0 0.8 

Confidence interval +|- 0.1 +|- 0.1 +|- 0.0 +|- 0.1 +|- 0.1 +|- 0.2 +|- 0.2 

Observations 156 171 211 170 161 117 200 

Data: Q.10Notes: Drops 3 outliers from the over 500,000 population category, each with over 100 ground 

The number of entry points are 68 for ground water systems and 5 for surface water syin the estimate.

19 
Table 8

Number of Systems Selling to Other Public Water Suppliers 

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Treated Water 0 334 655 465 325 44 67 Untreated Water 0 0 63 0 0 4 6 Observations 104 91 87 66 47 28 44 

Primarily Surface Water Systems

Treated Water 25 17 172 426 521 150 148 Untreated Water 19 0 0 11 39 3 12 Observations 44 53 68 73 80 56 105 

Primarily Purchased Water Systems

Treated Water 0 0 463 208 255 49 39 Untreated Water 0 0 0 0 16 0 7 Observations 5 23 50 26 27 30 47 

All Systems

Treated Water 25 351 1,290 1,099 1,101 243 255 Untreated Water 19 0 63 11 55 7 26 Observations 153 167 205 165 154 114 196 

Data: Q.5a

20 
Table 9

Water Systems Not Providing Any Treatment 

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Percent of Systems 35.2 22.1 14.8 13.9 2.0 3.0 2.6 

Confidence Interval +|- 13.1 +|- 11.2 +|- 9.3 +|- 10.1 +|- 3.9 +|- 5.2 +|- 4.3 

Number of Entry Points 1.2 1.4 2.6 3.3 2.0 20.0 3.0 

Confidence Interval +|- 0.1 +|- 0.3 +|- 1.1 +|- 1.3 +|- 0.0 +|- 0.0 +|- 0.0 

Observations 104 93 92 67 50 29 44 

Primarily Surface Water Systems

Percent of Systems 0.8 0.0 0.0 0.0 0.0 0.0 0.0 

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 

Number of Entry Points 1.0 0 0.0 0.0 0.0 0.0 0.0 

Confidence Interval +|- 0.0 0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 

Observations 46 55 69 76 83 58 110 

Primarily Purchased Water Systems

Percent of Systems 0.0 100.0 0.0 0.0 0.0 26.7 8.0 

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 27.4 +|- 8.7 

Number of Entry Points 0.0 1.0 0.0 0.0 0.0 10.5 5.0 

Confidence Interval 0.0 +|- 0.0 0.0 0.0 0.0 +|- 7.9 +|- 4.6 

Observations 1 3 8 10 8 25 

All Systems

Percent of Systems 33.0 21.1 12.5 9.9 1.1 3.3 2.0 

Confidence Interval +|- 12.3 +|- 10.3 +|- 7.8 +|- 7.3 +|- 2.1 +|- 3.2 +|- 2.1 

Number of Entry Points 1.2 1.4 2.6 3.3 2.0 13.7 3.9 

Confidence Interval +|- 0.1 +|- 0.3 +|- 1.1 +|- 1.3 +|- 0.0 +|- 6.9 +|- 2.4 

Observations 150 149 164 151 143 95 179 

Data: Q.10, Q.11Notes: *No data for these cells.

Estimate of number of entry points for systems that do not treat. Categories where all systas zero.Excludes systems that purchase 100% of their water.

21 
Table 10

Ground Water Entry Points Not Receiving Treatment

By System Service Population

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

# of Ground Water Entry Points Untreated per System 0.4 0.3 0.5 0.6 0.2 2.2 2.6 

Confidence Interval +|- 0.2 +|- 0.2 +|- 0.3 +|- 0.4 +|- 0.2 +|- 1.4 +|- 2.3 

% of Ground Water Entry Points Untreated per System 35.3 24.7 17.7 16.6 7.2 36.2 12.3 

Confidence Interval +|- 13.1 +|- 11.2 +|- 9.9 +|- 11.3 +|- 6.3 +|- 25.3 +|- 9.1 

Observations 104 93 92 60 44 26 42 

Primarily Surface Water Systems

# of Ground Water Entry Points Untreated per System 0.1 0.0 0.1 0.1 0.6 1.1 1.1 

Confidence Interval +|- 0.1 +|- 0.0 +|- 0.1 +|- 0.1 +|- 0.7 +|- 1.3 +|- 0.5 

% of Ground Water Entry Points Untreated per System 82.4 11.3 77.5 24.0 54.3 64.4 49.2 

Confidence Interval +|- 34.5 +|- 20.8 +|- 26.7 +|- 20.6 +|- 24.6 +|- 19.5 +|- 10.0 

Observations 46 55 69 76 83 58 109 

Primarily Purchased Water Systems

# of Ground Water Entry Points Untreated per System 0.0 0.1 0.0 0.0 0.5 0.7 1.2 

Confidence Interval +|- 0.0 +|- 0.1 +|- 0.0 +|- 0.0 +|- 0.5 +|- 1.0 +|- 0.8 

% of Ground Water Entry Points Untreated per System 0.0 100.0 0.0 0.0 45.6 44.5 28.4 

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 33.2 +|- 39.3 +|- 15.2 

Observations 6 23 50 25 26 29 45 

All Systems

# of Ground Water Entry Points Untreated per System 0.4 0.3 0.3 0.3 0.4 1.3 1.7 

Confidence Interval +|- 0.1 +|- 0.1 +|- 0.2 +|- 0.2 +|- 0.3 +|- 0.8 +|- 0.8 

% of Ground Water Entry Points Untreated per System 35.5 25.1 18.0 16.4 17.9 44.5 23.5 

Confidence Interval +|- 13.0 +|- 11.0 +|- 9.5 +|- 10.2 +|- 7.6 +|- 15.6 +|- 9.4 

Observations 156 171 211 161 153 113 196 

Data: Q.10, Q.11, Q.12Notes: * No observations.

Number of entry points that are not treating for all systems include treated and untreated entry Drops 2 outliers from the over 500,000 population category, each with over 100 ground water eground water entry points not receiving treatment are 27.5 and surface water entry points not rthis size category .

22 
Please note that the unit of analysis changes for the following tables. 

Tables 11-32 report data for treatment plants rather than water systems.

23 
Table 11

Treatment Plants per System

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001

500,000

Primarily Ground Water Systems100% Ground Water Systems

# Water Treatment Plants/System 1.1 1.4 1.5 2.3 2.4 6.3 5.2 

Confidence Interval +|- 0.1 +|- 0.2 +|- 0.3 +|- 0.5 +|- 0.7 +|- 3.3 +|- 4.0 

# Wells /Plant 1.2 1.4 1.5 2.0 3.0 2.6 2.8 

Confidence Interval +|- 0.1 +|- 0.2 +|- 0.3 +|- 0.6 +|- 1.1 +|- 1.4 +|- 1.5 

Observations 62 66 75 39 31 18 20 

Mostly Ground Water Systems

# Water Treatment Plants/System 1.3 1.4 2.1 2.0 4.7 1.4 3.5 

Confidence Interval +|- 0.4 +|- 0.5 +|- 0.5 +|- 0.6 +|- 2.0 +|- 0.5 +|- 1.2 

# Wells /Plant 1.0 1.0 1.0 1.8 1.6 4.1 6.1 

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.6 +|- 0.6 +|- 2.8 +|- 3.8 

% of Plants Treating Surface Water 0.4 26.1 10.0 17.4 2.9 57.9 11.4 

Confidence Interval +|- 1.0 +|- 29.4 +|- 17.5 +|- 11.0 +|- 4.2 +|- 33.5 +|- 7.0 

Observations 9 4 3 13 12 8 21 

Primarily Surface Water Systems100% Surface Water Systems

# Water Treatment Plants/System 1.0 1.0 1.0 1.1 1.0 1.2 1.3 

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.1 +|- 0.0 +|- 0.2 +|- 0.1 

Observations 40 48 56 61 64 35 68 

Mostly Surface Water Systems

# Water Treatment Plants/System 1.0 1.8 1.2 1.6 1.5 1.5 2.2 

Confidence Interval +|- 0.0 +|- 0.3 +|- 0.4 +|- 0.6 +|- 0.5 +|- 0.3 +|- 0.2 

# Wells /Plant 2.0 1.1 1.3 2.6 2.9 3.6 17.0 

Confidence Interval +|- 0.0 +|- 0.3 +|- 0.5 +|- 1.3 +|- 1.6 +|- 1.8 +|- 7.2 

% of Plants Treating Surface Water 76.9 54.7 88.5 62.0 74.8 84.4 75.0 

Confidence Interval +|- 40.0 +|- 9.1 +|- 12.8 +|- 22.2 +|- 25.6 +|- 10.4 +|- 7.8 

Observations 5 6 13 13 19 23 40 

24 
Table 11 (Cont.)

Treatment Plants per System

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001

500,000

Primarily Purchased Water Systems100% Purchased Water Systems

# Water Treatment Plants/System 1.0 1.0 1.0 1.0 1.2 1.6 1.4 

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.3 +|- 0.6 +|- 0.4 

Observations 4 6 6 3 6 6 9 

Mostly Purchased Water Systems

# Water Treatment Plants/System * * 1.5 1.6 2.6 11.5 3.7 

Confidence Interval * * +|- 0.6 +|- 0.4 +|- 0.9 +|- 14.1 +|- 2.4 

# Wells /Plant * * 1.0 3.2 1.3 1.2 3.4 

Confidence Interval * * +|- 0.0 +|- 2.8 +|- 0.4 +|- 0.3 +|- 2.6 

% of Plants Treating Surface Water * * 0.0 9.4 10.7 3.9 21.6 

Confidence Interval * * +|- 0.0 +|- 14.9 +|- 15.4 +|- 6.9 +|- 16.6 

Observations * * 3 6 8 5 20 

All Systems

# Water Treatment Plants/System 1.1 1.4 1.5 1.9 2.1 2.8 3.0 

Confidence Interval +|- 0.1 +|- 0.2 +|- 0.2 +|- 0.3 +|- 0.4 +|- 1.0 +|- 0.9 

# Wells /Plant 1.2 1.3 1.5 2.0 2.4 2.3 4.3 

Confidence Interval +|- 0.1 +|- 0.2 +|- 0.2 +|- 0.5 +|- 0.6 +|- 1.0 +|- 1.5 

% of Plants Treating Surface Water 8.9 8.6 9.5 17.8 22.7 30.3 27.3 

Confidence Interval +|- 5.4 +|- 4.3 +|- 3.3 +|- 3.9 +|- 4.6 +|- 11.4 +|- 7.1 

Observations 120 130 156 135 140 95 178 

Data: Q.10, Q.12Notes: *No data available for these cells.

Includes systems with at least one treatment plant only.Some systems have surface water with ground water feeding into it which then run through There are only 5 systems serving over 500,000 people with 100% ground water. Two of thetreatment plants and are excluded from the estimate. If included, the average number of tresystem are 92 for this stratum.

Definitions: See "Plant" definition in introduction.

25 
Table 12

Number of Wells Treated per Treatment Plant

By Treatment Plant's Water Source

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ground Water Plants

# Wells /Plant 1.2 1.3 1.5 2.4 2.3 2.3 3.8 

Confidence Interval +|- 0.1 +|- 0.2 +|- 0.2 +|- 1.0 +|- 0.6 +|- 1.0 +|- 1.4 

Observations 83 98 127 125 168 186 394 

Mixed Plants

# Wells /Plant 2.0 1.2 2.0 4.5 3.7 3.4 15.4 

Confidence Interval +|- 0.0 +|- 0.5 +|- 0.0 +|- 1.9 +|- 2.1 +|- 1.6 +|- 8.1 

Observations 1 3 1 8 10 4 21 

All Plants

# Wells /Plant 1.2 1.3 1.5 2.4 2.4 2.3 4.3 

Confidence Interval +|- 0.1 +|- 0.1 +|- 0.2 +|- 1.0 +|- 0.6 +|- 1.0 +|- 1.5 

Observations 84 101 128 133 178 190 415 

Data: Q.10, Q.12Notes: This table reports number of wells treated per ground water plant (ie: plants with zero we

Two systems serving over 500,000 people have over 190 wells, each with its own treatmfrom this estimate; if included the number of wells per ground water plant for systems serare 1.9.

26 
Table 13

Treatment Plant Flow Characteristics

By Type of Water Source

(Thousands of Gallons/Day)

System Service Population Category

100 

or Less

101 - 

500

501 - 

3,300 3,301 - 10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ground Water Plants

Average Daily Flow 6 30 106 461 1,148 3,142 4,251 Confidence Interval +|- 1 +|- 9 +|- 24 +|- 103 +|- 267 +|- 1,199 +|- 1,724 Peak Daily Flow 18 71 241 821 1,949 5,231 6,810 Confidence Interval +|- 8 +|- 27 +|- 41 +|- 187 +|- 430 +|- 1,624 +|- 2,809 Design Capacity 66 206 406 1,239 2,751 6,584 8,909 Confidence Interval +|- 26 +|- 80 +|- 95 +|- 229 +|- 747 +|- 2,376 +|- 3,174 

Surface Water Plants

Average Daily Flow 15 67 272 867 3,661 7,869 21,137 Confidence Interval +|- 9 +|- 32 +|- 54 +|- 138 +|- 769 +|- 1,266 +|- 1,671 Peak Daily Flow 24 130 498 1,420 5,936 13,184 34,104 Confidence Interval +|- 8 +|- 73 +|- 117 +|- 218 +|- 1,041 +|- 2,184 +|- 2,620 Design Capacity 39 227 888 2,146 8,404 17,129 42,530 Confidence Interval +|- 16 +|- 145 +|- 260 +|- 414 +|- 1,617 +|- 2,739 +|- 3,322 

Mixed Plants

Average Daily Flow * 11 120 522 4,017 6,272 22,112 Confidence Interval * +|- 8 +|- 0 +|- 240 +|- 2,445 +|- 2,369 +|- 3,463 

Peak Daily Flow * 28 135 1,041 8,260 8,383 38,680 Confidence Interval * +|- 31 +|- 0 +|- 562 +|- 7,580 +|- 3,015 +|- 6,423 Design Capacity * 46 154 1,717 11,986 13,492 60,581 Confidence Interval * +|- 29 +|- 0 +|- 796 +|- 10,098 +|- 6,623 +|- 10,534 

Water Source

27 
Table 13 (Cont.)

Treatment Plant Flow Characteristics

By Type of Water Source

(Thousands of Gallons/Day)

System Service Population Category

100 

or Less

101 - 

500

501 - 

3,300 3,301 - 10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

All Plants

Average Daily Flow 8 32 126 544 2,017 5,686 10,847 Confidence Interval +|- 2 +|- 9 +|- 25 +|- 92 +|- 369 +|- 1,158 +|- 2,076 Peak Daily Flow 19 75 272 945 3,383 9,471 17,645 Confidence Interval +|- 7 +|- 25 +|- 39 +|- 166 +|- 597 +|- 1,785 +|- 3,303 Design Capacity 61 204 464 1,431 4,794 12,257 22,978 Confidence Interval +|- 22 +|- 73 +|- 96 +|- 215 +|- 922 +|- 2,457 +|- 4,368 

Data: Q.7, Q.10, Q.12Notes: *No data available for these cells.

Excludes plants that treat only purchased treated water.Table presents average flows for plants in the sample. It includes only plants that reported complete production, peak daily production, and design capacity. One ground water system serving 25-100 people with four plants all having an average daily flow gredaily flow greater than 8 MGD, and a design capacity greater than 11 MGD was dropped. If included16,000 gallons of water per day, peak daily flow is 37,000 gallons of water per day, and design capacwater per day.One surface water plant with a capacity of 1.5 MGD in a system serving 25-100 people was excluded included, average daily flow is 17,000 gallons of water per day, peak daily flow is 27,000 gallons of wcapacity of 90,000 gallons of water per day.One ground water plant with a capacity of more than 400 MGD in a system serving greater than 500excluded from this estimate. If included, average daily flow is 25 MGD, peak daily flow is 54 MGD, an50 MGD.

Water Source

28 
Table 14

Comparison of Average Daily Treated Production to Treatment Design Capacity for Plants

By Primary Source of Water

System Service Population Category

Water Source 

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ground Water Plants

Ratio: Average Daily Production to Design Capacity 0.20 0.26 0.34 0.42 0.47 0.47 0.51 

Confidence interval +|- 0.09 +|- 0.10 +|- 0.07 +|- 0.11 +|- 0.07 +|- 0.06 +|- 0.08 

Ratio: Peak Daily Production to Design Capacity 0.43 0.52 0.71 0.69 0.78 0.89 0.91 

Confidence interval +|- 0.19 +|- 0.14 +|- 0.09 +|- 0.12 +|- 0.06 +|- 0.06 +|- 0.13 

Observations 31 64 90 93 85 68 205 

Surface Water Plants

Ratio: Average Daily Production to Design Capacity 0.53 0.42 0.36 0.45 0.45 0.46 0.53 

Confidence interval +|- 0.35 +|- 0.10 +|- 0.05 +|- 0.04 +|- 0.04 +|- 0.04 +|- 0.02 

Ratio: Peak Daily Production to Design Capacity 0.78 0.72 0.63 0.74 0.73 0.76 0.83 

Confidence interval +|- 0.26 +|- 0.07 +|- 0.08 +|- 0.06 +|- 0.05 +|- 0.05 +|- 0.03 

Observations 36 48 71 81 81 79 157 

Mixed Plants

Ratio: Average Daily Production to Design Capacity * 0.24 0.78 0.30 0.44 0.51 0.41 

Confidence interval * +|- 0.04 +|- 0.00 +|- 0.02 +|- 0.15 +|- 0.10 +|- 0.05 

Ratio: Peak Daily Production to Design Capacity * 0.52 0.88 0.61 0.65 0.70 0.70 

Confidence interval * +|- 0.13 +|- 0.00 +|- 0.15 +|- 0.18 +|- 0.18 +|- 0.07 

Observations * 3 1 7 9 4 27 

All Plants

Ratio: Average Daily Production to Design Capacity 0.25 0.28 0.34 0.43 0.46 0.46 0.51 

Confidence interval +|- 0.12 +|- 0.09 +|- 0.06 +|- 0.08 +|- 0.05 +|- 0.03 +|- 0.05 

Ratio: Peak Daily Production to Design Capacity 0.49 0.54 0.70 0.70 0.76 0.82 0.87 

Confidence interval +|- 0.06 +|- 0.08 +|- 0.05 +|- 0.03 +|- 0.05 +|- 0.03 +|- 0.04 

Observations 67 115 162 181 175 151 389 

Data: Q.10, Q.12Notes: * No data available for these cells.

Table presents average ratios for plants in the sample. It includes only plants that reported coaverage daily production, peak daily production, and design capacity. Excludes plants that treat only purchased treated water.One ground water system serving 25-100 people with four plants was dropped. This system hathe ratios.One surface water plant with a capacity of 1.5 MGD in a system serving 25-100 people was exestimate. This system has little impact on the ratios.One ground water plant with a capacity of more than 400 MGD in a system serving greater thaexcluded from this estimate. This system has little impact on the ratios.

29 
Table 15

Treatment Plants and Operator Hours per Week

By Primary Source of Water and System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ground Water Plants

% of Plants with 24/7 Operator 0.8 1.6 0.5 0.9 4.2 15.3 20.9 Avg. hours/week for systems without a 24/7 Operator 4.0 5.2 12.4 18.5 21.2 9.1 18.3 Observations 68 88 109 116 112 85 294 

Surface Water Plants

% of Plants with 24/7 Operator 0.0 0.0 0.9 15.8 51.4 65.6 84.1 Avg. hours/week for systems without a 24/7 Operator 8.4 21.0 45.1 60.4 102.3 65.6 32.8 Observations 46 55 74 80 84 78 165 

Mixed Plants

% of Plants with 24/7 Operator 0.0 0.0 0.0 8.9 53.1 71.5 68.7 Avg. hours/week for systems without a 24/7 Operator 3.0 3.4 43.0 54.8 59.4 48.0 40.9 Observations 1 3 1 8 10 4 27 

All Plants

% of Plants with 24/7 Operator 0.7 1.5 0.5 3.6 17.5 39.7 41.1 Avg. hours/week for systems without a 24/7 Operator 4.4 6.3 16.2 25.4 34.2 24.5 20.0 Observations 115 146 184 204 206 167 486 

Data: Q.17Notes: *No plants without a 24/7 operator in mixed plants serving greater than 500,000 peop

Excludes plants treating only purchased treated water.Some plants are not run 24 hours a day, 7 days a week and therefore do not require aa day, 7 days a week.

Definitions: "24/7" means that an Operator is on site 24 hours per day, 7 days per week.

30 
Table 16

Treatment Plants and Operator Hours per Week

By Primary Source of Water and Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 -

 0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Ov

1

Ground Water Plants

% of Plants with 24/7 Operator 2.5 0.2 0.7 12.7 52.0 0Avg. hours/week for systems without a 24/7 Operator 3.3 6.6 18.3 28.4 20.6 8Observations 106 157 303 275 49 

Surface Water Plants

% of Plants with 24/7 Operator 0.3 0.0 4.2 48.4 92.8 100Avg. hours/week for systems without a 24/7 Operator 5.8 18.3 49.6 91.5 50.6 Observations 28 79 138 178 245 2

Mixed Plants

% of Plants with 24/7 Operator 5.8 0.0 0.0 50.2 83.2 Avg. hours/week for systems without a 24/7 Operator 2.0 17.6 49.0 68.2 42.8 Observations 3 3 8 16 30 

All Plants

% of Plants with 24/7 Operator 2.5 0.1 1.2 28.7 84.3 95Avg. hours/week for systems without a 24/7 Operator 3.4 7.6 23.6 48.9 33.0 8

Observations 137 239 449 469 324 2

Data: Q.17Notes: *No observations.

Excludes plants treating only purchased treated water.Some plants are not run 24 hours a day, 7 days a week and therefore do nrequire an operator 24 hours a day, 7 days a week.

Definitions: "24/7" means that an Operator is on site 24 hours per day, 7 days per wee

31 
Table 17

Plants Lacking 24/7 Operator that Have SCADA Systems

By Primary Source of Water and System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ground Water Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 4.4 1.4 14.0 58.7 64.4 81.3 85.6 % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 5.4 3.8 15.5 20.1 53.2 57.6 42.4 Observations 63 82 106 113 108 71 234 

Surface Water Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 6.3 21.6 43.7 50.6 74.5 96.0 96.4 % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 3.0 18.5 31.9 26.4 61.0 93.0 67.5 Observations 46 55 73 65 38 20 25 

Mixed Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 0.0 0.0 0.0 39.1 46.0 100.0 100.0 % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 0.0 89.8 0.0 29.3 0.0 0.0 85.7 Observations 1 3 1 7 5 1 8 

All Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 4.6 2.8 17.2 57.1 65.6 85.4 86.7 % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 5.1 6.2 17.3 21.2 53.6 66.7 45.3 Observations 110 140 180 185 151 92 267 

Data: Q.17Notes: *No observations.Definitions: "24/7" means that an Operator is on site 24 hours per day, 7 days per week.

32 
Table 18

Systems Lacking 24/7 Operator that Have SCADA Systems

By Primary Source of Water and Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0 10.0 - 100.0

Over 

100 

Ground Water Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 4.2 8.1 39.8 81.7 79.6 100.0 % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 7.0 8.8 21.8 53.9 61.7 100.0 Observations 101 153 298 209 31 1 

Surface Water Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 5.5 20.5 45.7 69.8 100.0 * % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 2.4 14.7 31.9 53.2 69.7 * Observations 27 79 127 75 18 * 

Mixed Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 0.0 6.7 26.8 71.8 100.0 * % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 97.9 6.7 26.8 5.5 77.4 * Observations 2 3 8 8 5 * 

All Plants

% of Plants without a 24/7 Operator that Have SCADA Systems for Process Monitoring 4.2 9.1 40.6 77.9 88.1 100.0 % of Plants without a 24/7 Operator that Have SCADA Systems for Process Control 8.5 9.2 23.4 52.6 65.6 100.0 Observations 130 235 433 292 54 1 

Data: Q.7, Q.17Notes: *No observations.Definitions: "24/7" means that an Operator is on site 24 hours per day, 7 days per week.

33 
Table 19

Treatment Objectives

Percentage of Plants Having Each Treatment Objective

By Primary Source of Water and System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ov

500,0

Ground Water Plants

Algae control 0.0 0.0 0.0 4.3 0.0 2.3 5.5 0Corrosion control 4.9 14.7 38.1 31.9 43.2 24.5 23.5 49Disinfection 98.2 95.7 100.0 99.2 92.3 97.0 97.6 100Dechlorination 0.0 0.0 0.0 0.0 2.3 1.2 3.2 0Oxidation 2.3 8.0 17.0 12.1 16.9 2.7 15.7 2Iron Removal/Sequestration 31.9 55.5 57.6 35.0 22.6 26.9 21.8 4Manganese Removal/ Sequestration 0.0 17.3 24.4 23.8 17.5 26.9 19.0 2Fluoridation 0.0 4.0 19.3 37.9 20.0 30.5 24.5 5Taste/odor control 0.0 8.1 12.8 9.9 9.9 2.8 13.4 2TOC removal 0.0 0.0 0.2 3.8 0.8 3.1 9.1 0Particulate/ Turbidity Removal 16.4 3.5 6.8 15.2 6.6 6.3 13.0 2Softening 15.8 7.6 21.5 11.7 13.1 6.5 11.0 0Recarbonation 0.0 0.0 0.0 3.5 2.3 1.8 7.5 0Organic contaminant removal 1.7 0.0 2.2 4.4 3.3 6.0 8.5 Inorganic contaminant removal 0.0 6.0 0.9 6.8 5.1 2.7 3.4 0Radionuclides contaminant removal 0.0 2.2 2.2 3.2 2.0 3.2 1.4 0Other 0.0 0.0 0.0 1.1 7.0 3.9 0.4 0Observations 83 98 125 124 166 191 394 4

Surface Water Plants

Algae control 0.0 3.5 19.9 52.8 57.2 55.1 57.7 55Corrosion control 3.7 22.3 67.5 70.7 84.2 80.8 77.7 86Disinfection 97.6 99.3 100.0 99.0 100.0 100.0 100.0 100Dechlorination 0.0 0.0 1.4 3.7 3.7 6.2 3.5 7Oxidation 0.0 2.7 7.2 30.3 34.8 40.5 46.4 39Iron Removal/Sequestration 0.0 27.0 35.5 35.5 37.3 42.3 26.2 17Manganese Removal/ Sequestration 0.0 27.0 27.1 34.7 39.6 47.0 29.2 28Fluoridation 0.0 6.0 52.1 56.7 73.4 67.9 65.0 82Taste/odor control 6.3 9.4 46.6 71.2 74.0 73.7 67.4 79TOC removal 0.8 0.0 6.9 44.1 63.8 54.3 64.1 5Particulate/ Turbidity Removal 47.5 73.5 95.6 97.9 98.7 98.0 92.7 87Softening 16.8 0.0 14.5 25.2 19.8 12.4 5.3 9Recarbonation 0.0 0.0 7.3 12.0 6.9 8.3 5.8 5Organic contaminant removal 0.0 0.0 4.8 34.4 34.4 42.0 19.3 19Inorganic contaminant removal 1.2 20.7 2.7 22.7 25.2 29.1 15.6 12Radionuclides contaminant removal 0.0 0.0 1.3 8.3 9.8 17.1 3.4 4Other 0.0 0.0 0.0 1.2 5.8 1.4 1.2 9Observations 50 58 76 82 85 81 167 1

(Continue

34 
Table 19(Cont.)

Treatment Objectives

Percentage of Plants Having Each Treatment Objective

By Primary Source of Water and System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ov

500,0

Mixed Plants

Algae control * 0.0 * 30.2 31.8 60.1 41.6 66Corrosion control * 0.0 * 50.4 68.2 60.1 74.2 83Disinfection 100.0 100.0 100.0 100.0 97.3 100.0 100.0 100Dechlorination * 0.0 * 0.0 0.0 0.0 3.3 20Oxidation * 0.0 * 40.3 54.5 39.9 41.6 40Iron Removal/Sequestration * 3.4 * 40.3 42.7 0.0 24.1 0Manganese Removal/ Sequestration * 0.0 * 40.3 53.6 0.0 26.8 0Fluoridation * 0.0 * 60.5 64.5 100.0 57.4 0Taste/odor control * 6.8 * 50.4 65.4 60.1 63.1 100TOC removal * 0.0 * 10.1 75.4 100.0 44.7 100Particulate/ Turbidity Removal 100.0 10.2 * 65.1 86.3 100.0 82.6 100Softening * 0.0 * 10.1 43.6 20.2 30.6 0Recarbonation * 0.0 * 10.1 32.7 20.2 23.5 0Organic contaminant removal * 0.0 * 10.1 20.9 20.2 29.0 16Inorganic contaminant removal * 0.0 * 10.1 20.9 0.0 16.3 16Radionuclides contaminant removal * 0.0 * 20.2 10.0 0.0 6.3 16Other * 0.0 * 10.1 0.0 0.0 0.0 0Observations 1 3 1 9 11 4 29 

All Plants

Algae control 0.0 0.4 2.7 13.6 13.9 21.8 19.4 10Corrosion control 4.8 15.2 41.8 39.0 53.2 45.0 38.6 56Disinfection 98.2 96.0 100.0 99.2 94.1 98.1 98.3 100Dechlorination 0.0 0.0 0.2 0.7 2.6 2.7 3.2 Oxidation 2.0 7.2 15.9 16.0 21.8 14.3 24.0 8Iron Removal/Sequestration 28.8 52.2 55.2 35.2 26.4 31.3 22.9 7Manganese Removal/ Sequestration 0.0 17.9 24.7 26.2 23.2 32.6 21.8 6Fluoridation 0.0 4.1 23.5 41.7 33.2 42.1 35.5 25Taste/odor control 0.9 8.2 17.7 22.7 26.2 24.7 28.4 16TOC removal 0.1 0.0 1.0 11.3 17.2 19.4 23.6 9Particulate/ Turbidity Removal 20.9 12.8 23.1 32.7 29.8 35.1 35.2 17Softening 15.9 6.6 20.7 14.1 15.3 8.4 10.5 Recarbonation 0.0 0.0 0.9 5.1 4.1 3.9 7.8 Organic contaminant removal 1.5 0.0 2.6 10.4 10.8 16.8 11.9 6Inorganic contaminant removal 0.2 7.4 1.1 9.7 10.0 10.5 6.9 3Radionuclides contaminant removal 0.0 1.9 2.1 4.5 4.0 8.2 2.1 0Other 0.0 0.0 0.0 1.3 6.6 2.9 0.6 Observations 134 159 202 215 262 276 590 5

Data: Q.13Notes: *No observations.

Excludes plants that treat purchased water.

35 
Table 20

Treatment Objectives

Percentage of Plants Having Each Treatment Objective 

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 All 

Ground Water Plants

Algae control 0.0 0.0 2.3 1.3 12.7 0.0 Corrosion control 9.6 26.9 36.2 39.3 18.7 0.0 Disinfection 95.8 98.1 99.6 97.7 97.0 100.0 Dechlorination 0.0 0.0 0.7 2.2 7.8 0.0 Oxidation 2.2 9.3 19.0 24.5 26.5 0.0 Iron Removal/Sequestration 34.3 51.2 43.9 39.7 74.1 0.0 Manganese Removal/ Sequestration 0.3 23.7 22.9 30.2 81.2 0.0 Fluoridation 2.4 11.2 27.9 37.9 32.2 0.0 Taste/odor control 0.0 8.1 14.5 17.1 29.1 0.0 TOC removal 0.0 0.1 2.1 4.5 14.0 0.0 Particulate/ Turbidity Removal 8.7 2.6 11.9 18.3 24.7 0.0 Softening 18.1 10.4 16.1 20.6 20.4 0.0 Recarbonation 0.0 0.0 1.3 8.7 14.4 0.0 Organic contaminant removal 1.5 1.6 2.5 10.7 2.6 0.0 Inorganic contaminant removal 0.0 4.9 5.0 8.4 4.0 0.0 Radionuclides contaminant removal 0.0 1.1 3.2 4.2 1.2 0.0 Other 0.0 0.5 2.0 11.9 3.2 0.0 Observations 118 161 347 333 84 1 

Surface Water Plants

Algae control 3.3 1.0 37.5 55.6 61.2 45.8 Corrosion control 7.3 24.2 65.0 84.2 83.4 79.2 Disinfection 95.2 100.0 99.5 100.0 100.0 100.0 Dechlorination 0.0 0.0 2.4 4.2 5.7 4.2 Oxidation 1.5 1.0 17.8 35.3 47.1 20.8 Iron Removal/Sequestration 3.6 18.6 40.5 36.3 27.7 8.3 Manganese Removal/ Sequestration 3.6 18.6 34.4 40.2 31.0 16.0 Fluoridation 3.9 10.4 51.6 68.8 79.8 70.8 Taste/odor control 14.5 14.0 56.4 75.0 71.5 72.0 TOC removal 5.2 2.6 27.2 56.0 58.6 37.5 Particulate/ Turbidity Removal 61.2 72.7 97.8 98.0 94.6 80.0 Softening 35.3 4.5 15.3 21.2 8.2 8.3 Recarbonation 0.0 0.0 9.5 8.3 7.0 4.2 Organic contaminant removal 0.0 2.6 22.1 33.1 19.5 8.3 Inorganic contaminant removal 5.9 16.8 15.3 21.9 17.1 8.3 Radionuclides contaminant removal 0.0 0.0 4.1 9.8 5.1 0.0 Other 0.0 3.7 1.3 3.6 2.6 12.0 Observations 28 80 138 179 247 25 

(Continued)

36 
Table 20 (Cont.)

Treatment Objectives

Percentage of Plants Having Each Treatment Objective 

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100

Mixed Plants

Algae control 0.0 6.7 22.2 46.9 42.9 * Corrosion control 5.9 6.7 56.5 64.2 57.2 * Disinfection 100.0 100.0 100.0 100.0 100.0 * Dechlorination 0.0 0.0 0.0 0.0 5.5 * Oxidation 5.9 0.0 56.5 26.5 60.4 * Iron Removal/Sequestration 0.0 31.3 33.3 42.6 43.3 * Manganese Removal/ Sequestration 0.0 0.0 45.4 41.4 45.7 * Fluoridation 5.9 0.0 44.4 82.1 50.6 * Taste/odor control 5.9 62.0 56.5 51.7 82.7 * TOC removal 5.9 6.7 23.2 52.1 71.3 * Particulate/ Turbidity Removal 7.8 100.0 62.0 89.2 91.4 * Softening 5.9 0.0 0.0 44.9 27.0 * Recarbonation 5.9 0.0 0.0 33.8 20.7 * Organic contaminant removal 0.0 0.0 11.1 22.7 27.4 * Inorganic contaminant removal 0.0 0.0 11.1 21.3 16.5 * Radionuclides contaminant removal 0.0 0.0 17.9 7.7 7.9 * Other 0.0 0.0 8.9 0.0 0.0 * Observations 3 3 8 17 30 * 

All Plants

Algae control 0.2 0.1 8.1 25.8 44.2 43.8 Corrosion control 9.3 26.6 40.9 59.0 60.7 75.6 Disinfection 95.8 98.2 99.6 98.7 99.0 100.0 Dechlorination 0.0 0.0 1.0 2.9 6.4 4.0 Oxidation 2.3 8.4 19.2 29.1 41.4 19.9 Iron Removal/Sequestration 32.2 48.0 43.3 38.4 44.1 8.0 Manganese Removal/ Sequestration 0.4 23.1 24.9 34.7 48.2 15.3 Fluoridation 2.6 11.0 31.8 52.3 62.1 67.7 Taste/odor control 1.1 9.0 22.2 43.1 58.6 68.9 TOC removal 0.5 0.4 6.2 28.3 45.0 35.8 Particulate/ Turbidity Removal 12.2 12.5 29.9 54.8 71.9 76.6 Softening 18.5 9.7 15.8 21.6 13.5 8.0 Recarbonation 0.2 0.0 2.6 9.3 10.3 4.0 Organic contaminant removal 1.4 1.7 5.8 20.7 14.6 8.0 Inorganic contaminant removal 0.3 6.2 6.7 14.4 12.8 8.0 Radionuclides contaminant removal 0.0 1.0 3.5 6.6 4.1 0.0 Other 0.0 0.7 2.0 8.2 2.6 11.5 Observations 149 244 493 529 361 26 

Data: Q.13Notes: *No observations.

Excludes plants that treat purchased water.

37 
Table 21

Treatment Schemes

Percentage of Plants Using Each Treatment Scheme

By Primary Source of Water and System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Ground Water Plants

Disinfection with no additional treatment 68.7 55.5 52.1 37.4 43.5 54.2 60.3 Other chemical addition 7.7 21.7 11.4 30.5 15.8 15.0 2.7 Ion exchange, Activated Alumina, Aeration 0.0 9.8 22.0 18.7 23.1 25.3 14.1 Other filtration (not direct or conventional) 12.3 9.5 3.9 4.6 9.0 0.6 7.0 Direct filtration 0.1 0.0 0.1 0.2 0.3 0.6 0.2 Conventional filtration 0.0 0.0 0.0 2.6 0.0 0.0 0.0 Membranes 1.1 0.0 0.1 0.5 0.0 0.6 0.6 Softening 10.0 3.6 6.9 5.5 6.9 1.4 3.7 Observations 83 98 127 125 168 191 394 

Surface Water Plants

Disinfection with no additional treatment 50.0 14.3 3.6 1.0 0.3 0.0 2.4 Other chemical addition 0.0 0.0 4.3 1.0 0.0 1.0 4.2 Ion exchange, Activated Alumina, Aeration 0.0 2.3 2.1 7.1 6.5 5.3 4.6 Other filtration (not direct or conventional) 12.8 28.4 14.5 6.0 0.0 11.1 2.3 Direct filtration 7.2 18.8 9.2 16.9 15.5 8.9 13.5 Conventional filtration 11.9 8.9 37.4 35.7 59.2 60.7 64.5 Membranes 6.4 5.8 1.3 1.0 0.0 0.0 0.6 Softening 11.7 20.8 27.6 30.2 16.3 12.9 6.7 Observations 50 58 76 82 85 81 169 

Mixed Plants

Disinfection with no additional treatment 0.0 89.8 100.0 46.7 14.2 0.0 3.2 Other chemical addition 0.0 0.0 0.0 0.0 2.7 0.0 14.2 Ion exchange, Activated Alumina, Aeration 0.0 0.0 0.0 14.6 0.0 28.5 16.3 Other filtration (not direct or conventional) 0.0 3.4 0.0 0.0 0.0 0.0 3.2 Direct filtration 0.0 6.8 0.0 7.3 9.6 0.0 3.2 Conventional filtration 100.0 0.0 0.0 16.8 31.5 57.1 40.5 Membranes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Softening 0.0 0.0 0.0 14.6 42.0 14.4 16.3 Observations 1 3 1 9 11 4 29 

(Contin

38 
Table 21 (Cont.)

Treatment Schemes

Percentage of Plants Using Each Treatment Scheme

By Primary Source of Water and System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

All Plants

Disinfection with no additional treatment 67.0 52.9 47.5 31.8 33.5 37.3 43.9 Other chemical addition 7.0 19.8 10.7 25.1 12.1 10.6 3.6 Ion exchange, Activated Alumina, Aeration 0.0 9.1 20.1 16.7 19.0 19.3 11.9 Other filtration (not direct or conventional) 12.4 10.8 4.9 4.7 6.9 3.7 5.7 Direct filtration 0.7 1.5 1.0 3.1 3.8 3.1 3.6 Conventional filtration 1.1 0.7 3.5 8.2 13.5 18.9 17.3 Membranes 1.6 0.4 0.2 0.6 0.0 0.4 0.6 Softening 10.2 4.8 8.9 9.6 9.7 5.0 4.9 Observations 134 159 204 216 264 276 592 

Data: Q.14ANotes: Excludes plants that treat purchased water.Definitions: See treatment scheme description in Volume I.

39 
Table 22

Treatment Schemes

Percentage of Plants Using Each Treatment Scheme

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 A

Ground Water Plants

Disinfection with no additional treatment 64.3 57.7 37.9 41.2 14.5 100.0 Other chemical addition 11.0 16.9 18.4 12.2 6.5 0.0 Ion exchange, Activated Alumina, Aeration 0.0 14.4 29.4 24.7 72.3 0.0 Other filtration (not direct or conventional) 13.1 5.1 5.6 9.1 1.4 0.0 Direct filtration 0.0 0.1 0.2 0.3 0.7 0.0 Conventional filtration 0.0 0.0 1.3 0.0 0.0 0.0 Membranes 0.9 0.1 0.3 0.4 0.0 0.0 Softening 10.7 4.6 4.1 10.1 4.7 0.0 Observations 118 161 347 333 84 1 

Surface Water Plants

Disinfection with no additional treatment 32.6 26.9 5.5 0.3 0.9 8.0 Other chemical addition 0.0 2.0 1.5 1.0 3.0 12.0 Ion exchange, Activated Alumina, Aeration 0.0 2.8 3.6 6.7 6.0 0.0 Other filtration (not direct or conventional) 15.6 28.1 11.8 2.3 0.6 0.0 Direct filtration 11.8 16.6 14.2 10.5 18.9 20.0 Conventional filtration 7.2 14.3 34.5 60.0 58.2 48.0 Membranes 8.7 4.1 2.2 0.9 0.0 0.0 Softening 24.2 5.1 26.2 16.3 11.2 12.0 Observations 28 80 138 179 247 25 

Mixed Plants

Disinfection with no additional treatment 92.2 0.0 42.8 30.5 2.7 * Other chemical addition 0.0 0.0 0.0 0.0 5.9 * Ion exchange, Activated Alumina, Aeration 0.0 0.0 17.9 3.3 11.4 * Other filtration (not direct or conventional) 0.0 31.3 0.0 0.0 2.7 * Direct filtration 0.0 62.0 0.0 15.4 2.7 * Conventional filtration 2.0 6.7 30.4 16.8 57.7 * Membranes 0.0 0.0 0.0 0.0 0.0 * Softening 5.8 0.0 8.9 34.0 14.1 * Observations 3 3 8 17 30 * 

(Continued)

40 
Table 22 (Cont.)

Treatment Schemes

Percentage of Plants Using Each Treatment Scheme

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 A

All Plants

Disinfection with no additional treatment 63.6 55.3 32.8 24.6 5.4 12.0 Other chemical addition 10.4 15.7 15.5 7.3 4.3 11.5 Ion exchange, Activated Alumina, Aeration 0.0 13.5 25.2 16.8 27.8 0.0 Other filtration (not direct or conventional) 12.9 6.9 6.6 6.0 1.0 0.0 Direct filtration 0.5 1.4 2.4 4.9 11.9 19.1 Conventional filtration 0.3 1.1 6.8 24.4 39.4 45.9 Membranes 1.2 0.4 0.6 0.6 0.0 0.0 Softening 11.1 4.6 7.7 13.5 9.3 11.5 Observations 149 244 493 529 361 26 

Data: Q.14ANotes: *No data available for these cells.

Excludes plants that treat purchased water.

Definitions: See treatment scheme description in Volume I.

41 
Table 23

Treatment Practices for Surface Water Plants

Percentage of Plants Performing Each Treatment

By Primary Source of Water and System Service Population

System Service Population Category

Surface Water Treatment Practice

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Chlorination only 49.5 32.4 7.9 6.0 0.3 1.0 6.8 Raw water storage/Presedimentation basin 12.5 20.5 11.5 16.3 20.5 29.8 19.1 Predisinfection/oxidation prior to sedimentation

Chlorine 18.6 2.9 37.6 50.9 51.7 45.8 52.2 Chlorine dioxide 0.0 0.0 0.0 3.0 3.9 11.4 7.4 Chloramines 0.0 0.0 0.0 1.0 8.3 0.0 10.0 Ozone 0.5 0.9 0.0 1.0 0.0 5.3 3.9 Potassium permanganate 0.0 1.1 24.9 29.4 37.1 29.2 27.8 Other Predisinfection 0.0 0.0 4.8 1.0 0.0 0.0 1.7 

Predisinfection/Oxidation prior to filtration

Chlorine 7.4 11.9 24.2 24.3 35.4 38.3 31.5 Chlorine dioxide 0.0 2.0 0.0 0.0 1.1 2.0 2.8 Chloramines 0.0 0.0 0.0 0.0 4.6 1.3 6.9 Ozone 0.0 15.3 0.0 0.0 1.1 2.3 4.1 Potassium permanganate 0.0 1.2 6.9 10.1 5.5 7.8 3.9 Other Predisinfection 0.0 0.0 4.4 0.0 0.0 2.0 0.0 

Rapid mix 7.8 13.1 43.3 67.5 90.9 75.6 77.8 Coagulation/ Flocculation 11.0 22.6 63.1 87.9 96.4 82.0 85.2 Polymers 15.5 21.5 54.4 63.7 62.1 53.4 58.4 Settling/Sedimentation 11.9 15.9 60.8 67.9 79.8 74.7 71.7 Softening

Lime/soda ash 0.0 20.8 27.6 34.2 20.7 12.9 7.2 Recarbonation 0.0 0.0 0.0 6.1 7.7 5.0 4.4 Ion exchange 11.7 0.0 0.0 0.0 0.0 0.0 0.0 

Filtration

Direct filtration 2.6 2.3 0.8 8.1 5.3 4.0 9.6 Micro strainer 0.0 0.0 0.0 0.0 0.0 0.0 1.7 Slow sand 4.9 10.8 4.8 3.1 0.0 0.0 1.7 Bag and Cartridge 18.9 18.6 0.0 0.0 1.0 0.0 0.6 Rapid sand 0.0 9.4 24.5 32.5 17.6 7.9 16.2 Green sand 0.7 0.0 3.0 1.0 0.0 0.0 0.6 Diatomaceous earth 2.6 1.0 2.5 2.0 0.0 13.1 2.9 Dual/Multi media 13.7 14.0 51.8 46.6 73.2 68.7 59.3 Pressure filtration 9.5 20.7 2.2 2.6 0.0 2.0 0.0 Other filtration 0.6 0.8 4.1 0.0 3.9 2.3 3.0 

(Contin

42 
Table 23 (Cont.)

Treatment Practices for Primarily Surface Water Systems

Percentage of Plants Performing Each Treatment

By Primary Source of Water and System Service Population

System Service Population Category

Surface Water Treatment Practice

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Post-disinfection after filters

Chlorine 27.8 58.3 77.4 85.3 83.7 75.3 74.5 Chlorine dioxide 0.0 0.0 0.0 1.0 5.0 1.5 0.6 Chloramines 0.0 0.0 0.0 4.1 22.5 18.9 23.6 Ozone 0.0 0.7 0.0 0.0 0.0 5.3 0.0 UV 11.7 0.0 0.0 0.0 0.0 0.0 0.6 Other post disinfection 0.0 0.0 7.9 0.0 2.1 1.0 1.1 Clearwell 11.0 37.4 80.0 81.0 82.7 85.4 82.0 

Membranes

Reverse osmosis 2.0 0.0 0.0 0.0 0.0 0.0 0.0 Micro filtration 6.4 5.8 1.3 1.0 0.0 0.0 0.6 Ultrafiltration 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Nanofiltration 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Corrosion Control 1.5 14.1 40.8 48.9 70.6 62.9 69.7 Miscellaneous

Ion exchange 0.0 0.0 0.0 1.0 0.0 0.0 0.0 Granular activated carbon 2.2 2.6 0.8 21.1 14.9 15.9 11.0 Activated Alumina 0.0 2.3 0.0 1.0 0.0 1.3 1.1 Aeration 0.0 0.0 2.1 6.1 7.6 5.0 5.7 

Other

Flouride 0.0 2.5 37.4 57.3 69.4 60.4 64.4 PAC 0.0 1.1 5.7 6.1 18.7 12.3 18.1 Ph Adjust 0.0 0.0 6.1 1.0 1.1 1.0 3.3 Iron/Mag. removal/seq. 0.0 2.0 0.0 0.0 0.0 0.0 0.0 Taste/oder 0.0 0.0 0.0 1.0 0.3 0.0 1.2 Filter aid 0.0 0.0 7.7 5.9 2.2 1.0 0.0 Clarify 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Blending 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Data: Q.14ANotes: Represents treatment practices for plants treating water that comes entirely or partly from s

Percentages may not sum to 100 percent because systems may perform more than one tre

Definition: Cholorination only is indicated when a plant chlorinated but did not filter. It includes plants 

chlorinated and plants that chlorinated and used other non-filtration practices.

43 
Table 24

Treatment Practices for Ground Water Plants

Percentage of Plants Performing Each Treatment

By Primary Source of Water and System Service Population

System Service Population Category

Ground Water Treatment Practice

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ove

500,000 

Chlorination only 81.4 73.2 72.7 72.5 67.8 71.1 68.6 96.9 Raw water storage/Presedimentation basin 1.5 0.0 0.4 1.6 1.4 1.2 5.8 0.0 Predisinfection/oxidation prior to sedimentation

Chlorine 0.0 7.5 9.4 10.6 11.3 5.9 9.5 0.0 Chlorine dioxide 0.0 0.0 0.0 0.0 0.7 10.5 0.4 0.0 Chloramines 0.0 0.0 0.0 0.0 0.0 0.6 4.5 0.0 Ozone 0.5 0.0 0.0 0.0 0.0 0.0 0.9 0.0 Potassium permanganate 0.0 3.7 3.2 4.4 0.7 1.2 0.4 0.0 Other Predisinfection 1.3 0.0 0.0 0.0 0.7 0.0 4.9 0.0 

Predisinfection/Oxidation prior to filtration

Chlorine 1.5 7.1 10.0 7.5 10.8 1.2 3.0 2.5 Chlorine dioxide 0.0 0.0 0.0 0.0 0.0 0.4 0.0 0.0 Chloramines 0.0 0.0 0.0 0.0 0.0 1.2 0.4 0.0 Ozone 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Potassium permanganate 1.0 1.4 5.0 2.4 4.0 0.0 0.4 0.0 Other Predisinfection 0.0 1.2 0.0 0.0 0.0 0.0 0.0 0.0 

Rapid mix 0.0 0.0 2.4 5.0 0.0 3.0 2.7 0.0 Coagulation/ Flocculation 0.0 0.0 4.3 6.0 2.6 4.7 1.7 0.0 Polymers 0.1 0.0 8.4 3.5 2.2 2.2 1.0 0.0 Settling/Sedimentation 0.0 0.0 4.3 8.1 5.4 3.6 3.0 0.2 Softening

Lime/soda ash 3.4 2.5 10.3 8.2 9.1 4.7 12.7 0.4 Recarbonation 0.0 0.0 1.0 5.1 2.2 1.8 7.1 0.2 Ion exchange 6.6 2.2 6.0 2.3 3.6 0.6 0.0 0.0 

Filtration

Direct filtration 1.1 0.0 0.0 2.5 0.0 1.2 0.2 0.0 Micro strainer 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Slow sand 0.0 0.0 1.0 3.4 0.0 0.0 0.2 0.0 Bag and Cartridge 8.9 0.1 0.4 0.0 0.0 0.0 0.2 0.0 Rapid sand 0.0 0.9 2.7 7.2 4.4 1.2 2.0 0.0 Green sand 1.6 7.5 4.2 4.4 2.9 0.0 0.4 0.0 Diatomaceous earth 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 Dual/Multi media 0.1 0.0 4.6 3.4 5.7 3.2 10.5 2.5 Pressure filtration 0.0 3.7 8.1 2.6 7.2 1.2 1.0 0.0 Other filtration 0.8 2.1 0.0 0.3 0.3 0.8 0.0 0.0 

(Continued)

44 
Table 24 (Cont.)

Treatment Practices for Primarily Ground Water Systems

Percentage of Plants Performing Each Treatment

By Primary Source of Water and System Service Population

System Service Population Category

Ground Water Treatment Practice

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ove

500,000 

Post-disinfection after filters

Chlorine 8.5 7.8 15.3 21.0 19.9 3.3 11.5 2.7 Chlorine dioxide 0.0 0.0 0.0 0.0 0.0 0.0 6.6 0.0 Chloramines 0.0 0.0 0.0 0.8 1.4 1.8 3.4 0.0 Ozone 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 UV 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Other post disinfection 0.0 0.0 1.4 0.0 0.0 5.8 0.0 0.0 Clearwell 11.4 15.4 24.7 23.6 16.0 6.9 13.3 0.4 

Membranes

Reverse osmosis 1.1 0.0 0.1 0.5 0.0 0.6 0.6 0.0 Micro filtration 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 Ultrafiltration 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Nanofiltration 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Corrosion Control 8.0 17.6 17.4 28.9 21.2 19.0 7.3 0.8 Miscellaneous

Ion exchange 0.0 0.0 0.0 0.0 1.4 0.0 0.0 0.0 Granular activated carbon 0.0 0.0 0.0 0.8 1.9 0.6 8.6 0.2 Activated Alumina 0.0 0.0 0.0 0.0 0.0 18.1 0.0 0.0 Aeration 0.0 9.8 22.0 19.0 21.7 7.9 17.4 14.9 

Other

Flouride 0.0 4.4 18.3 27.6 20.5 9.4 12.1 0.6 PAC 0.0 0.0 0.0 0.0 0.0 0.0 0.4 0.0 Ph Adjust 0.0 1.2 4.7 0.0 2.2 0.0 0.0 0.0 Iron/Mag. removal/seq. 2.3 3.8 3.0 4.7 1.4 0.6 0.0 0.0 Taste/oder 0.0 0.0 0.0 1.6 0.0 0.0 0.0 0.0 Filter aid 0.0 0.0 3.5 0.0 0.0 0.0 5.8 0.0 Clarify 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Blending 0.0 2.0 0.0 6.0 0.7 1.2 0.2 0.0 

Data: Q.14ANotes: Represents treatment practices for plants treating water that comes entirely or partly from ground  Percentages may not sum to 100 percent because systems may perform more than one treatmeDefinition: Cholorination only is indicated when a plant chlorinated but did not filter. It includes plants that o

plants that chlorinated and used other non-filtration practices.

45 
Table 25

Treatment Practices for Surface Water Plants

Percentage of Plants Performing Each Treatment

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Surface Water Treatment Practice

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 All Siz

Chlorination only 32.6 28.9 9.0 1.3 4.6 20.0 1Raw water storage/Presedimentation basin 25.9 19.5 11.3 22.0 23.0 28.0 1Predisinfection/oxidation prior to sedimentation

Chlorine 30.5 5.7 44.5 47.7 53.9 52.0 3Chlorine dioxide 0.0 0.0 1.5 4.1 8.4 4.0 Chloramines 0.0 0.0 1.8 4.9 6.3 12.0 Ozone 0.0 0.8 0.0 1.1 5.1 4.0 Potassium permanganate 2.6 3.7 24.9 33.3 33.6 12.0 2Other Predisinfection 0.0 0.0 3.0 0.8 0.6 0.0 

Predisinfection/Oxidation prior to filtration

Chlorine 12.3 15.6 22.5 32.2 39.9 32.0 2Chlorine dioxide 0.0 0.0 1.1 1.1 1.9 0.0 Chloramines 0.0 0.0 0.0 3.8 5.7 4.0 Ozone 0.3 13.0 0.0 0.9 3.7 8.0 Potassium permanganate 0.0 1.0 7.9 7.8 3.0 4.0 Other Predisinfection 0.0 0.0 2.8 0.2 0.6 0.0 

Rapid mix 11.5 15.2 54.5 80.6 81.9 60.0 5Coagulation/ Flocculation 17.1 27.5 70.7 91.1 89.4 76.0 6Polymers 12.3 30.9 56.9 56.0 59.8 60.0 4Settling/Sedimentation 7.9 19.6 61.2 80.8 71.2 60.0 5Softening

Lime/soda ash 0.7 5.1 28.3 19.5 11.5 12.0 1Recarbonation 0.0 0.0 1.6 8.4 4.5 0.0 Ion exchange 23.5 0.0 0.0 0.0 0.0 0.0 

Filtration

Direct filtration 1.8 2.5 3.8 6.8 5.6 12.0 Micro strainer 0.0 0.0 0.0 0.3 0.3 0.0 Slow sand 7.2 7.9 5.0 1.6 0.6 0.0 Bag and Cartridge 35.0 16.8 0.0 0.7 0.3 0.0 Rapid sand 0.4 9.1 24.7 20.8 20.8 28.0 1Green sand 0.0 1.9 1.0 0.7 0.0 0.0 Diatomaceous earth 0.0 2.5 2.2 3.4 1.2 0.0 Dual/Multi media 16.7 21.1 49.3 62.1 66.4 48.0 4Pressure filtration 9.2 20.2 3.0 0.0 0.0 0.0 Other filtration 1.1 1.1 2.3 3.1 1.6 8.0 

(Continued)

46 
Table 25 (Cont.)

Treatment Practices for Primarily Surface Water Systems

Percentage of Plants Performing Each Treatment

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Surface Water Treatment Practice

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 All Siz

Post-disinfection after filters

Chlorine 29.0 58.1 80.6 82.2 72.7 44.0 7Chlorine dioxide 0.0 0.0 1.3 2.5 1.3 0.0 Chloramines 0.0 0.0 2.3 18.7 20.4 40.0 Ozone 0.0 0.0 0.4 0.4 1.8 0.0 UV 23.5 0.0 0.0 0.0 0.3 0.0 Other post disinfection 0.0 3.7 2.6 1.5 1.3 0.0 Clearwell 10.9 42.6 76.6 83.7 79.9 68.0 6

Membranes

Reverse osmosis 4.0 0.0 0.0 0.0 0.0 0.0 Micro filtration 8.7 4.1 2.2 0.9 0.0 0.0 Ultrafiltration 0.0 0.0 0.0 0.0 0.0 0.0 Nanofiltration 0.0 0.0 0.0 0.0 0.0 0.0 

Corrosion Control 2.9 17.9 38.5 68.7 73.9 68.0 4Miscellaneous

Ion exchange 0.0 0.0 0.5 0.0 0.0 0.0 Granular activated carbon 1.8 3.0 10.0 14.9 10.8 4.0 Activated Alumina 0.0 2.8 0.0 0.4 0.6 0.0 Aeration 0.0 0.0 3.6 7.3 7.0 0.0 

Other

Flouride 2.9 8.0 40.8 64.8 75.7 72.0 3PAC 0.0 0.0 7.1 15.6 16.7 32.0 Ph Adjust 0.0 0.0 4.4 1.0 2.7 0.0 Iron/Mag. removal/seq. 0.0 0.0 1.1 0.0 0.0 0.0 Taste/oder 0.0 0.0 0.0 0.9 0.7 0.0 Filter aid 0.0 3.7 5.5 1.8 0.0 0.0 Clarify 0.0 0.0 0.0 0.0 0.0 0.0 Blending 0.0 0.0 0.0 0.0 0.0 0.0 

Data: Q.14ANotes: Represents treatment practices for plants treating water that comes entirely or partly . from ground sources. Percentages may not sum to 100 percent because systems

may perform more than one treatment. 

Definition: Cholorination only is indicated when a plant chlorinated but did not filter. It includes pla

only chlorinated and plants that chlorinated and used other non-filtration practices.

47 
Table 26

Treatment Practices for Ground Water Plants

Percentage of Plants Performing Each Treatment

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Ground Water Treatment Practice

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100

Siz

Chlorination only 80.7 72.5 66.5 52.8 67.6 100.0 7Raw water storage/Presedimentation basin 1.2 0.0 1.3 4.4 2.3 0.0 Predisinfection/oxidation prior to sedimentation

Chlorine 0.0 9.1 13.3 17.2 7.7 0.0 Chlorine dioxide 0.0 0.0 0.2 0.1 0.0 0.0 Chloramines 0.0 0.0 0.0 1.4 3.9 0.0 Ozone 0.0 0.2 0.0 0.4 0.0 0.0 Potassium permanganate 0.5 3.1 5.1 3.4 2.8 0.0 Other Predisinfection 1.1 0.0 0.1 2.7 0.7 0.0 

Predisinfection/Oxidation prior to filtration

Chlorine 6.3 6.7 9.0 20.5 8.5 0.0 Chlorine dioxide 0.0 0.0 0.0 0.0 0.0 0.0 Chloramines 0.0 0.0 0.0 0.2 3.0 0.0 Ozone 0.0 0.0 0.0 0.0 0.0 0.0 Potassium permanganate 1.1 3.7 3.3 3.5 0.0 0.0 Other Predisinfection 0.0 1.0 0.0 0.0 0.0 0.0 

Rapid mix 0.0 0.0 4.8 3.3 5.3 0.0 Coagulation/ Flocculation 0.0 0.8 6.3 7.8 5.3 0.0 Polymers 0.1 3.4 6.3 3.9 4.6 0.0 Settling/Sedimentation 0.0 0.0 9.5 8.8 5.6 0.0 Softening

Lime/soda ash 3.5 3.6 11.0 18.1 22.0 0.0 Recarbonation 0.0 0.0 3.4 7.4 13.5 0.0 Ion exchange 7.2 2.7 5.8 1.5 0.0 0.0 

Filtration

Direct filtration 0.0 0.6 0.9 2.2 1.6 0.0 Micro strainer 0.0 0.0 0.0 0.0 0.0 0.0 Slow sand 0.0 0.0 2.9 0.0 0.0 0.0 Bag and Cartridge 3.3 0.3 0.0 0.1 0.0 0.0 Rapid sand 0.0 1.5 5.3 10.3 4.3 0.0 Green sand 8.1 4.2 4.6 0.3 0.0 0.0 Diatomaceous earth 0.0 0.0 0.1 0.0 0.0 0.0 Dual/Multi media 0.0 0.1 7.4 10.6 22.9 0.0 Pressure filtration 0.0 4.3 9.4 10.8 0.0 0.0 Other filtration 1.6 1.2 0.3 0.2 0.0 0.0 

(Continued)

48 
Table 26 (Cont.)

Treatment Practices for Primarily Ground Water Systems

Percentage of Plants Performing Each Treatment

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Ground Water Treatment Practice

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100

Siz

Post-disinfection after filters

Chlorine 7.1 10.9 25.0 23.1 7.4 0.0 1Chlorine dioxide 0.0 0.0 0.0 1.3 10.4 0.0 Chloramines 0.0 0.0 0.4 3.6 5.9 0.0 Ozone 0.0 0.0 0.0 0.0 0.0 0.0 UV 0.0 0.0 0.0 0.0 0.0 0.0 Other post disinfection 0.0 0.0 1.7 1.2 0.0 0.0 Clearwell 8.0 21.4 26.6 27.5 24.0 0.0 1

Membranes

Reverse osmosis 0.9 0.1 0.3 0.4 0.0 0.0 Micro filtration 0.0 0.0 0.1 0.0 0.0 0.0 Ultrafiltration 0.0 0.0 0.0 0.0 0.0 0.0 Nanofiltration 0.0 0.0 0.0 0.0 0.0 0.0 

Corrosion Control 11.9 13.3 26.3 21.4 12.3 0.0 1Miscellaneous

Ion exchange 0.0 0.0 0.0 2.5 0.0 0.0 Granular activated carbon 0.0 0.0 0.6 2.2 1.4 0.0 Activated Alumina 0.0 0.0 0.0 0.0 48.9 0.0 Aeration 0.0 14.4 29.7 23.2 23.4 0.0 1

Other

Flouride 1.2 9.1 25.3 29.6 24.2 0.0 1PAC 0.0 0.0 0.0 0.0 1.2 0.0 Ph Adjust 0.0 3.2 2.0 3.8 0.0 0.0 Iron/Mag. removal/seq. 1.9 4.8 3.5 2.0 1.6 0.0 Taste/oder 0.0 0.0 0.4 2.0 0.0 0.0 Filter aid 0.0 1.2 2.7 0.0 0.0 0.0 Clarify 0.0 0.0 0.0 0.0 0.0 0.0 Blending 0.0 1.7 2.6 3.7 0.0 0.0 

Data: Q.14ANotes: Represents treatment practices for plants treating water that comes entirely or partly fr

ground sources. Percentages may not sum to 100 percent because systems may perfmore than one treatment. 

Definition: Cholorination only is indicated when a plant chlorinated but did not filter. It includes pla

only chlorinated and plants that chlorinated and used other non-filtration practices.

49 
Table 27

Concentration of Various Contaminants in Very Large Ground Water and Surface Water Systems

Across All Wells and Intakes By Primary Source of Water

(Average Raw Water Concentration in Parts per Million, Except for Radon, Which is pCi/L)

Water Source and Contaminant

% Reporting 

N/A

% Reporting 

No Detect

Mean 

Concentration

Median 

Concentration

90th Percentile 

Concentration Observ

Ground Water

Arsenic 19.2 11.5 0.010 0.007 0.025 Radon 80.8 2.6 371.1 417.5 554.5 MTBE 33.3 48.7 0.175 0.004 0.050 Atrazine 33.3 57.7 0.043 0.001 0.210 Metolachlor 47.4 44.9 0.053 0.001 0.210 Boron 51.3 2.6 0.173 0.120 0.273 2,4-D 34.6 57.7 0.001 0.001 0.001 Simazine 32.1 59.0 0.043 0.001 0.210 Glyphosate 34.6 56.4 0.002 0.001 0.006 

Surface water

Arsenic 31.1 17.8 0.004 0.002 0.005 Radon 67.8 13.3 75.3 51.0 219.0 MTBE 24.4 41.1 0.005 0.001 0.005 Atrazine 40.0 34.4 0.014 0.000 0.043 Metolachlor 44.4 36.7 0.001 0.001 0.005 Boron 55.6 22.2 0.082 0.059 0.180 2,4-D 33.3 46.7 0.006 0.001 0.010 Simazine 38.9 40.0 0.001 0.000 0.001 Glyphosate 45.6 38.9 0.016 0.016 0.025 

Data: Q.15ANotes: The data presented in this table were requested only of systems serving populations of 

than 500,000. Unweighted data. Data are for wells and surface water intakes reported by systems in the survey. Mean, median, 90th percentile, and number of observations are for wells ansurface water intakes with positive concentrations.This table reports results for the type of raw water treated, not the primary source of wathe sytem. Two systems reported very high arsenic concentrations and are excluded from the ana

50 
Table 28

Concentration of Various Contaminants in Very Large Systems

Across All Entry Points By Primary Source of Water

(Average Finished Water Concentration in Parts per Million, Except for Radon, Which is pCi/L)

Primary Source of Water and Contaminant

% Reporting 

N/A

% Reporting 

No Detect

Mean 

Concentration

Median 

Concentration

90th Percentile 

Concentration Observ

Primarily Ground Water Systems

Arsenic 79.5 2.3 0.004 0.004 0.008 Radon 90.9 0.0 118.0 118.0 118.0 MTBE 79.5 13.6 0.000 0.000 0.000 Atrazine 79.5 9.1 0.205 0.205 0.210 Metolachlor 79.5 9.1 0.205 0.205 0.210 Boron 81.8 0.0 0.132 0.102 0.234 2,4-D 84.1 9.1 0.000 0.000 0.000 Simazine 79.5 9.1 0.205 0.205 0.210 Glyphosate 84.1 9.1 0.000 0.000 0.000 

Primarily Surface Water Systems

Arsenic 9.1 40.4 0.003 0.002 0.005 Radon 52.5 23.2 60.4 47.0 189.0 MTBE 21.2 40.4 0.005 0.001 0.005 Atrazine 19.2 40.4 0.011 0.000 0.001 Metolachlor 21.2 49.5 0.001 0.000 0.004 Boron 60.6 9.1 0.123 0.056 0.500 2,4-D 18.2 52.5 0.029 0.001 0.015 Simazine 21.2 39.4 0.001 0.000 0.001 Glyphosate 33.3 39.4 0.013 0.006 0.025 

Primarily Purchased Water Systems

Arsenic 0.0 5.5 0.009 0.010 0.014 Radon 21.8 10.9 460.1 447.0 646.0 MTBE 5.5 74.5 0.001 0.001 0.001 Atrazine 0.0 65.5 0.040 0.040 0.080 Metolachlor 1.8 67.3 0.000 0.000 0.000 Boron 78.2 1.8 0.155 0.164 0.200 2,4-D 0.0 61.8 0.000 0.000 0.000 Simazine 0.0 83.6 0.001 0.001 0.001 Glyphosate 0.0 83.6 0.006 0.006 0.006 

Data: Q.15BNotes: The data presented in this table were requested only of systems serving populations of 

than 500,000. Unweighted data. Data are for wells and surface water intakes reported by systems in the survey. Mean, median, 90th percentile, and number of observations are for test poiwith positive concentrations.

(Continued)

51 
Table 28 (Cont.)

Concentration of Various Contaminants in Very Large Systems

Because the test points for finished water may be in the distribution system, this table dnot report results for the type of water treated; instead, it reports results by the primarysource of water for the system.Four systems were excluded because 1) reported arsenic concentrations may be incor2) reported boron concentrations may be incorrect, or 3) they reported finished but not water concentrations.

52 
Table 29

Residual Management Process Options

Percentage of Plants Using Each Residual Management Process

By Primary Source of Water and Water System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

5

Ground Water Plants

Mechanical dewatering 3.9 0.0 0.0 0.0 8.3 0.0 5.6 Non-mechanical dewatering 3.6 0.0 3.5 5.7 5.2 4.8 17.8 Chemical precipitation 0.0 0.0 0.0 0.3 1.0 5.5 4.3 Land application 3.5 3.0 10.8 8.3 6.7 7.8 15.0 Non-hazardous waste landfill 16.4 0.0 6.1 1.9 3.1 5.5 4.1 Deep well Injection 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Evaporation Pond 0.0 0.0 8.4 9.6 3.5 7.4 2.7 French Drain 0.0 1.9 3.2 0.0 0.0 0.0 0.4 Direct Discharge to Surface Water 6.6 4.4 11.7 3.3 7.0 4.0 17.0 Septic system 0.0 2.8 0.0 0.0 0.0 1.6 0.0 Sanitary Sewer 0.8 6.0 12.5 7.0 15.1 12.4 6.0 

Surface Water Plants

Mechanical dewatering 0.0 1.1 5.7 13.4 10.7 17.1 20.1 Non-mechanical dewatering 3.6 21.4 34.4 44.9 36.2 58.2 51.1 Chemical precipitation 0.0 0.0 1.4 22.0 7.2 18.2 16.8 Land application 7.1 18.2 27.1 27.4 42.2 52.4 29.4 Non-hazardous waste landfill 4.4 9.5 21.3 25.2 24.5 35.1 37.2 Deep well Injection 0.0 0.0 0.0 0.0 0.0 0.0 0.6 Evaporation Pond 17.4 60.1 23.4 46.2 37.8 47.3 47.8 French Drain 3.6 2.1 4.3 0.0 2.4 6.5 3.1 Direct Discharge to Surface Water 8.4 32.5 29.5 32.4 17.2 16.2 14.7 Septic system 1.4 3.4 2.5 3.6 0.0 4.4 1.4 Sanitary sewer 0.0 5.6 23.0 15.2 29.1 22.2 13.1 

(Cont

53 
Table 29 (Cont.)

Residual Management Process Options

Percentage of Plants Using Each Residual Management Process

By Primary Source of Water and Water System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

5

Mixed Plants

Mechanical dewatering 0.0 0.0 0.0 8.1 21.0 39.9 16.3 Non-mechanical dewatering 0.0 0.0 0.0 31.4 41.1 71.5 56.8 Chemical precipitation 0.0 0.0 0.0 8.1 0.0 39.9 24.2 Land application 0.0 0.0 0.0 8.1 10.5 20.2 34.7 Non-hazardous waste landfill 0.0 0.0 0.0 8.1 10.5 57.1 38.4 Deep well Injection 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Evaporation Pond 0.0 66.4 0.0 32.2 41.1 39.9 48.3 French Drain 0.0 0.0 0.0 0.0 10.5 0.0 3.2 Direct Discharge to Surface Water 100.0 33.6 0.0 24.1 31.5 39.9 19.5 Septic system 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Sanitary sewer 0.0 0.0 0.0 14.6 10.5 0.0 19.5 

All Plants

Mechanical dewatering 3.5 0.1 1.0 2.3 9.2 10.5 11.4 Non-mechanical dewatering 3.6 2.3 9.4 12.7 13.5 36.9 32.2 Chemical precipitation 0.0 0.0 0.2 4.0 2.4 13.3 10.0 Land application 4.0 4.7 14.0 11.3 15.2 33.9 21.5 Non-hazardous waste landfill 15.0 1.0 8.8 6.0 8.3 23.5 17.8 Deep well Injection 0.0 0.0 0.0 0.0 0.0 0.0 0.2 Evaporation Pond 2.1 6.8 11.1 16.1 12.7 30.9 21.7 French Drain 0.4 1.9 3.4 0.0 0.8 3.7 1.5 Direct Discharge to Surface Water 6.9 7.5 15.0 8.8 10.0 11.6 16.3 Septic system 0.2 2.9 0.4 0.4 0.0 3.0 0.5 Sanitary sewer 0.7 5.9 13.4 8.5 18.0 16.4 8.8 

Data: Q.16ANotes: Excludes plants that treat purchased water.

54 
Table 30

Residual Management Process Options

Percentage of Plants Using Each Residual Management Process

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 A

Ground Water Plants

Mechanical dewatering 1.7 0.0 1.1 7.3 3.0 0.0 Non-mechanical dewatering 1.5 0.1 3.5 9.4 13.6 0.0 Chemical precipitation 0.0 0.0 0.3 1.2 3.9 0.0 Land application 1.4 2.0 6.1 9.9 11.8 0.0 Non-hazardous waste landfill 2.1 0.3 2.8 6.2 3.4 0.0 Deep well Injection 0.0 0.0 0.0 0.0 0.0 0.0 Evaporation Pond 0.0 0.0 6.6 7.9 5.8 0.0 French Drain 1.0 0.0 1.1 0.0 0.7 0.0 Direct Discharge to Surface Water 2.8 2.1 5.3 10.4 3.9 0.0 Septic system 0.0 1.4 0.0 0.0 1.2 0.0 Sanitary Sewer 2.2 7.5 15.0 16.1 8.2 0.0 

Surface Water Plants

Mechanical dewatering 1.6 0.0 6.9 11.0 20.1 12.0 Non-mechanical dewatering 1.1 12.8 29.5 36.9 45.4 44.0 Chemical precipitation 1.1 0.0 7.4 11.0 12.8 16.0 Land application 2.4 9.3 20.6 42.4 25.0 16.0 Non-hazardous waste landfill 4.9 8.4 15.6 21.2 32.8 8.0 Deep well Injection 0.0 0.0 0.0 0.0 0.3 0.0 Evaporation Pond 10.3 26.8 30.2 34.7 42.5 28.0 French Drain 3.2 3.0 0.8 1.5 2.5 0.0 Direct Discharge to Surface Water 9.3 14.8 26.2 16.4 14.3 16.0 Septic system 2.9 1.1 2.4 0.6 1.9 0.0 Sanitary sewer 2.6 6.7 17.3 28.7 18.7 24.0 

(Continued)

55 
Table 30 (Cont.)

Residual Management Process Options

Percentage of Plants Using Each Residual Management Process

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 A

Mixed Plants

Mechanical dewatering 5.8 0.0 8.9 11.7 16.2 * Non-mechanical dewatering 5.8 6.7 38.5 34.0 36.4 * Chemical precipitation 0.0 0.0 8.9 6.2 10.9 * Land application 0.0 0.0 0.0 19.0 25.5 * Non-hazardous waste landfill 0.0 6.7 8.9 15.0 29.9 * Deep well Injection 0.0 0.0 0.0 0.0 0.0 * Evaporation Pond 0.0 68.7 27.6 48.3 27.1 * French Drain 0.0 0.0 0.0 8.4 2.7 * Direct Discharge to Surface Water 7.8 31.3 29.6 20.1 23.8 * Septic system 2.0 0.0 0.0 0.0 0.0 * Sanitary Sewer 0.0 0.0 27.6 0.0 16.8 * 

All Plants

Mechanical dewatering 1.7 0.0 2.1 8.9 14.3 11.5 Non-mechanical dewatering 1.6 1.0 8.0 21.2 34.5 42.1 Chemical precipitation 0.0 0.0 1.5 5.3 9.8 15.3 Land application 1.4 2.6 8.4 23.1 20.8 15.3 Non-hazardous waste landfill 2.2 0.9 4.9 12.4 23.1 7.7 Deep well Injection 0.0 0.0 0.0 0.0 0.2 0.0 Evaporation Pond 0.4 2.1 10.6 20.0 29.6 26.8 French Drain 1.0 0.2 1.0 0.9 1.9 0.0 Direct Discharge to Surface Water 3.2 3.1 8.9 13.1 11.6 15.3 Septic system 0.1 1.4 0.4 0.2 1.5 0.0 Sanitary sewer 2.2 7.4 15.5 20.5 15.2 23.0 

Data: Q.16ANotes: *No data available for these cells.

Excludes plants that treat only purchased treated water.

56 
Table 31

Residual Management Process Options 

Percentage of Plants That Discharge to Surface Water, Septic Systems, or Sanitary Sewers

By Primary Source of Water and Water System Service Population

System Service Population Category

Water Source

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Ground Water Plants

Direct Discharge to Surface Water 100.0 100.0 100.0 63.9 66.7 100.0 95.9 Septic system 100.0 100.0 * 0.0 * 100.0 * Sanitary sewer 100.0 100.0 97.4 87.8 81.9 94.2 61.1 

Surface Water Plants

Direct Discharge to Surface Water 100.0 100.0 92.1 80.2 48.7 54.1 62.2 Septic system 100.0 100.0 100.0 75.0 0.0 100.0 80.0 Sanitary sewer * 100.0 93.9 66.9 69.0 88.2 62.6 

Mixed Plants

Direct Discharge to Surface Water 100.0 100.0 * 40.2 61.0 100.0 75.5 Septic system 100.0 * * 0.0 0.0 * 0.0 Sanitary sewer * * * 33.8 50.0 * 60.7 

All Plants

Direct Discharge to Surface Water 100.0 100.0 97.0 69.7 57.6 59.4 80.2 Septic system 100.0 100.0 100.0 25.3 0.0 100.0 66.7 Sanitary sewer 100.0 100.0 96.8 76.3 76.2 90.6 61.7 

Data: Q.16ANotes: *No observations for these plants

Excludes plants that treat purchased water.These are the systems with the option to discard to surface water, septic systems, or sanitaand make use of these options.

57 
Table 32

Residual Management Process Options 

Percentage of Plants That Do Discharge to Surface Water, Septic Systems, or Sanitary Sewers

By Primary Source of Water and Plant Average Daily Production

Plant Average Daily Production (MGD)

Water Source

0 - 

0.01

0.01 - 

0.1

0.1 - 

1.0

1.0 -

10.0

10.0 - 

100.0

Over 

100 A

Ground Water Plants

Direct Discharge to Surface Water 100.0 100.0 77.8 89.2 76.8 * Septic system * 100.0 0.0 0.0 100.0 * Sanitary sewer 100.0 99.8 90.3 84.7 81.1 * 

Surface Water Plants

Direct Discharge to Surface Water 100.0 89.2 92.3 54.9 48.2 100.0 Septic system 100.0 100.0 56.3 12.9 75.9 0.0 Sanitary sewer 100.0 100.0 80.7 81.6 50.8 75.0 

Mixed Plants

Direct Discharge to Surface Water 100.0 100.0 35.5 72.3 81.4 * Septic system 100.0 * 0.0 0.0 0.0 * Sanitary sewer * * 44.1 0.0 56.3 * 

All Plants

Direct Discharge to Surface Water 100.0 95.8 80.8 67.5 53.5 100.0 Septic system 100.0 100.0 28.4 11.0 73.3 * Sanitary sewer 100.0 99.8 86.9 81.8 54.8 75.0 

Data: Q.16ANotes: *No observations for these plants

Excludes plants that treat purchased water.These are the systems with the option to discard to surface water, septic systemor sanitary sewers, and make use of these options.

58 
Please note that the unit of analysis changes for the following tables. 

The remaining tables report data for water systems except where noted.

59 
Table 33

Treated-Water Storage Information 

Percentage of Systems That Have Each Type of Treated-Water Storage

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Clearwell storage after treatment 16.3 21.3 26.9 28.9 45.6 56.2 40.4 

Confidence Interval +|- 10.2 +|- 9.8 +|- 10.7 +|- 12.6 +|- 14.1 +|- 19.7 +|- 26.0 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points 26.4 36.7 17.0 23.1 18.5 33.9 22.3 

Confidence Interval +|- 9.6 +|- 12.7 +|- 8.3 +|- 10.1 +|- 11.0 +|- 17.4 +|- 14.3 

With a Common Inlet and Outlet 18.4 15.3 15.6 8.8 10.1 23.0 8.0 

Confidence Interval +|- 9.8 +|- 8.8 +|- 11.4 +|- 9.5 +|- 8.3 +|- 26.8 +|- 6.9 

Storage within the distribution system

With Dedicated Entry and Exit Points 2.9 3.0 10.0 16.5 25.4 38.4 46.2 

Confidence Interval +|- 4.4 +|- 3.5 +|- 7.0 +|- 8.9 +|- 12.4 +|- 18.6 +|- 27.2 

With a Common Inlet and Outlet 6.9 17.0 68.6 54.0 67.1 74.4 93.6 

Confidence Interval +|- 6.3 +|- 8.6 +|- 15.0 +|- 12.9 +|- 13.4 +|- 15.0 +|- 5.7 

Primarily Surface Water SystemsClearwell storage after treatment 48.5 33.7 86.2 85.3 93.7 97.1 93.9 

Confidence Interval +|- 35.7 +|- 21.0 +|- 8.8 +|- 10.3 +|- 5.0 +|- 3.5 +|- 2.7 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points 36.8 45.9 16.6 27.7 31.2 33.5 37.3 

Confidence Interval +|- 31.4 +|- 24.4 +|- 8.7 +|- 10.4 +|- 10.0 +|- 13.8 +|- 5.9 

With a Common Inlet and Outlet 4.4 8.7 18.3 16.7 7.8 7.1 12.8 

Confidence Interval +|- 4.9 +|- 7.6 +|- 10.3 +|- 10.9 +|- 6.6 +|- 9.4 +|- 4.3 

Storage within the distribution system

With Dedicated Entry and Exit Points 1.3 10.8 4.1 29.2 33.9 45.7 54.0 

Confidence Interval +|- 2.8 +|- 13.0 +|- 4.0 +|- 11.1 +|- 10.0 +|- 13.6 +|- 5.9 

With a Common Inlet and Outlet 10.2 30.8 73.6 73.0 69.5 76.2 72.9 

Confidence Interval +|- 9.7 +|- 26.7 +|- 12.0 +|- 11.9 +|- 10.1 +|- 15.0 +|- 5.3 

(C

60 
Table 33 (Cont.)

Treated-Water Storage Information 

Percentage of Systems That Have Each Type of Treated-Water Storage

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Purchased Water Systems

Clearwell storage after treatment 23.1 0.7 3.1 12.1 14.0 12.4 33.4 

Confidence Interval +|- 46.9 +|- 1.5 +|- 4.1 +|- 12.4 +|- 13.3 +|- 10.0 +|- 10.5 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points 0.0 21.3 5.3 13.5 12.5 11.4 33.7 

Confidence Interval +|- 0.0 +|- 34.8 +|- 7.5 +|- 12.1 +|- 12.8 +|- 9.7 +|- 11.0 

With a Common Inlet and Outlet 10.0 11.1 7.6 15.3 0.6 2.5 0.0 

Confidence Interval +|- 22.7 +|- 16.5 +|- 7.6 +|- 17.4 +|- 1.2 +|- 4.2 +|- 0.0 

Storage within the distribution system

With Dedicated Entry and Exit Points 0.0 7.1 8.8 22.6 34.2 36.9 53.6 

Confidence Interval +|- 0.0 +|- 11.2 +|- 11.2 +|- 17.1 +|- 20.0 +|- 15.6 +|- 11.8 

With a Common Inlet and Outlet 0.0 28.9 55.4 61.6 72.3 55.6 70.8 

Confidence Interval +|- 0.0 +|- 25.9 +|- 17.5 +|- 19.0 +|- 18.6 +|- 16.4 +|- 10.9 

All SystemsClearwell storage after treatment 18.5 19.5 25.5 36.9 54.2 62.8 61.0 

Confidence Interval +|- 10.0 +|- 8.2 +|- 7.5 +|- 8.7 +|- 8.2 +|- 6.7 +|- 11.9 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points 26.9 35.3 13.8 22.2 21.3 27.8 30.9 

Confidence Interval +|- 9.2 +|- 10.9 +|- 6.8 +|- 7.0 +|- 6.7 +|- 8.5 +|- 7.6 

With a Common Inlet and Outlet 17.4 14.3 13.6 11.6 7.2 10.5 8.3 

Confidence Interval +|- 9.1 +|- 7.3 +|- 7.8 +|- 7.1 +|- 4.3 +|- 9.9 +|- 3.2 

Storage within the distribution system

With Dedicated Entry and Exit Points 2.8 4.1 9.1 20.2 30.2 41.3 51.0 

Confidence Interval +|- 4.1 +|- 3.3 +|- 5.3 +|- 6.8 +|- 7.8 +|- 9.2 +|- 11.2 

With a Common Inlet and Outlet 7.1 19.5 65.4 59.2 69.0 70.2 80.2 

Confidence Interval +|- 5.9 +|- 8.0 +|- 11.1 +|- 9.1 +|- 8.1 +|- 8.8 +|- 5.5 

Data: Q.18Notes: Column totals do not sum to 100.

61 
Table 34

Treated-Water Storage Information - Average Capacity for Each Type of Treated-Water Storage

By Primary Source of Water

(In Millions of Gallons)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water SystemsClearwell storage after treatment 0.010 0.047 0.118 0.371 1.284 1.267 2.557 

Confidence Interval +|- 0.007 +|- 0.047 +|- 0.071 +|- 0.153 +|- 0.665 +|- 0.868 +|- 0.706 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points 0.012 0.633 0.295 0.826 4.030 8.925 14.903 

Confidence Interval +|- 0.010 +|- 1.152 +|- 0.206 +|- 0.255 +|- 2.158 +|- 5.902 +|- 4.545 

With a Common Inlet and Outlet 0.073 0.085 0.130 1.258 1.400 3.670 35.461 

Confidence Interval +|- 0.140 +|- 0.054 +|- 0.072 +|- 0.342 +|- 1.314 +|- 0.689 +|- 48.457 

Storage within the distribution system

With Dedicated Entry and Exit Points 0.009 0.038 0.175 0.931 1.932 6.316 13.202 

Confidence Interval +|- 0.003 +|- 0.048 +|- 0.205 +|- 0.412 +|- 1.280 +|- 3.237 +|- 4.115 

With a Common Inlet and Outlet 0.187 0.097 0.221 1.002 3.947 12.387 9.783 

Confidence Interval +|- 0.187 +|- 0.037 +|- 0.055 +|- 0.282 +|- 1.576 +|- 5.451 +|- 6.516 

Total Storage Capacity 0.050 0.325 0.271 1.092 4.652 17.232 21.170 

Confidence Interval +|- 0.047 +|- 0.507 +|- 0.065 +|- 0.210 +|- 1.299 +|- 4.946 +|- 11.816 

Primarily Surface Water SystemsClearwell storage after treatment 0.131 0.102 0.162 0.421 1.379 3.075 11.626 

Confidence Interval +|- 0.143 +|- 0.084 +|- 0.058 +|- 0.116 +|- 0.474 +|- 0.772 +|- 2.138 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points 0.030 0.109 0.374 1.061 2.874 6.438 29.628 

Confidence Interval +|- 0.026 +|- 0.080 +|- 0.178 +|- 0.360 +|- 0.933 +|- 3.805 +|- 7.982 

With a Common Inlet and Outlet 0.042 0.217 0.359 1.556 2.653 1.023 7.356 

Confidence Interval +|- 0.035 +|- 0.176 +|- 0.183 +|- 1.096 +|- 0.746 +|- 1.801 +|- 2.003 

Storage within the distribution system

With Dedicated Entry and Exit Points * 0.350 0.995 0.774 4.057 17.252 46.256 

Confidence Interval * +|- 0.127 +|- 0.593 +|- 0.195 +|- 1.456 +|- 12.894 +|- 17.009 

With a Common Inlet and Outlet 0.214 0.192 0.487 1.294 4.088 6.775 17.810 

Confidence Interval +|- 0.153 +|- 0.035 +|- 0.132 +|- 0.389 +|- 1.138 +|- 1.535 +|- 2.454 

Total Storage Capacity 0.113 0.203 0.682 2.034 6.576 17.992 60.729 

Confidence Interval +|- 0.097 +|- 0.077 +|- 0.124 +|- 0.346 +|- 1.367 +|- 6.486 +|- 10.636 

(Co

62 
Table 34 (Cont.)

Treated-Water Storage Information - Average Capacity for Each Type of Treated-Water Storage

By Primary Source of Water

(In Millions of Gallons)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Purchased Water SystemsClearwell storage after treatment 0.018 0.028 0.192 0.299 0.931 1.529 7.965 

Confidence Interval +|- 0.000 +|- 0.000 +|- 0.043 +|- 0.327 +|- 0.972 +|- 1.829 +|- 1.855 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points * 0.017 0.654 1.087 1.083 7.639 26.495 

Confidence Interval * +|- 0.001 +|- 0.252 +|- 0.410 +|- 0.574 +|- 3.860 +|- 11.631 

With a Common Inlet and Outlet 0.053 0.046 0.227 0.184 116.500 3.000 * 

Confidence Interval +|- 0.000 +|- 0.048 +|- 0.096 +|- 0.197 +|- 0.000 +|- 0.000 * 

Storage within the distribution system

With Dedicated Entry and Exit Points * 0.020 0.228 1.053 3.118 8.256 26.016 

Confidence Interval * +|- 0.025 +|- 0.118 +|- 0.501 +|- 1.236 +|- 3.604 +|- 6.367 

With a Common Inlet and Outlet * 0.175 0.289 0.845 4.045 15.510 23.809 

Confidence Interval * +|- 0.155 +|- 0.153 +|- 0.300 +|- 1.498 +|- 6.176 +|- 5.711 

Total Storage Capacity 0.029 0.088 0.313 1.116 5.626 17.403 44.501 

Confidence Interval +|- 0.021 +|- 0.073 +|- 0.133 +|- 0.494 +|- 2.356 +|- 5.954 +|- 7.554 

All SystemsClearwell storage after treatment 0.031 0.054 0.134 0.389 1.316 2.533 9.075 

Confidence Interval +|- 0.022 +|- 0.043 +|- 0.050 +|- 0.094 +|- 0.371 +|- 0.660 +|- 1.854 

Storage after treatment, before distribution system

With Dedicated Entry and Exit Points 0.013 0.537 0.343 0.912 3.083 7.470 25.156 

Confidence Interval +|- 0.009 +|- 0.963 +|- 0.154 +|- 0.191 +|- 0.982 +|- 3.157 +|- 5.140 

With a Common Inlet and Outlet 0.073 0.087 0.172 1.052 4.408 2.826 13.961 

Confidence Interval +|- 0.137 +|- 0.048 +|- 0.076 +|- 0.458 +|- 5.542 +|- 1.874 +|- 11.235 

Storage within the distribution system

With Dedicated Entry and Exit Points 0.009 0.091 0.224 0.915 3.053 12.093 30.863 

Confidence Interval +|- 0.003 +|- 0.069 +|- 0.154 +|- 0.242 +|- 0.827 +|- 6.310 +|- 8.935 

With a Common Inlet and Outlet 0.190 0.122 0.263 1.040 4.018 10.363 15.448 

Confidence Interval +|- 0.169 +|- 0.042 +|- 0.055 +|- 0.194 +|- 0.850 +|- 2.515 +|- 4.410 

Total Storage Capacity 0.055 0.289 0.318 1.286 5.518 17.637 42.835 

Confidence Interval +|- 0.043 +|- 0.411 +|- 0.053 +|- 0.175 +|- 0.902 +|- 3.689 +|- 9.901 

Data: Q.18Notes: *No data available for these cells.

Clearwell storage after treatment for ground water systems serving over 500,000 people is based on 1 o

63 
Table 35

Distribution System Summary - Pipes

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Miles of Pipe in Place 3 5 25 61 203 339 560 

Confidence interval +|- 2 +|- 1 +|- 11 +|- 22 +|- 77 +|- 46 +|- 149 

Service Connections per Mile 24 33 49 58 68 69 58 

Confidence interval +|- 11 +|- 9 +|- 10 +|- 9 +|- 20 +|- 5 +|- 11 

Average Annual Pipe Replaced in the Past 5 Years (miles) 0 0 1 2 5 8 20 

Confidence interval +|- 0 +|- 0 +|- 0 +|- 1 +|- 2 +|- 2 +|- 12 

Average Cost per Mile of Pipe Replaced in the Past 5 Years (thousands of dollars) 738 119 131 239 260 380 462 

Confidence interval +|- 557 +|- 51 +|- 49 +|- 89 +|- 67 +|- 109 +|- 93 

Observations 16 67 158 113 108 82 139 

Private Systems

Miles of Pipe in Place 1 4 37 217 390 871 777 

Confidence interval +|- 1 +|- 2 +|- 25 +|- 189 +|- 367 +|- 834 +|- 133 

Service Connections per Mile 59 71 49 37 47 66 64 

Confidence interval +|- 14 +|- 21 +|- 27 +|- 18 +|- 23 +|- 22 +|- 9 

Average Annual Pipe Replaced in the Past 5 Years (miles) 0 0 1 20 5 3 20 

Confidence interval +|- 0 +|- 0 +|- 1 +|- 33 +|- 5 +|- 2 +|- 11 

Average Cost per Mile of Pipe Replaced in the Past 5 Years (thousands of dollars) 31 90 106 62 103 438 623 

Confidence interval +|- 15 +|- 36 +|- 130 +|- 51 +|- 80 +|- 63 +|- 238 

Observations 131 90 30 19 17 10 16 

(Co

64
Table 35 (Cont.)

Distribution System Summary - Pipes

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

All Systems

Miles of Pipe in Place 1 4 28 85 232 395 579 

Confidence interval +|- 1 +|- 1 +|- 10 +|- 37 +|- 85 +|- 100 +|- 141 

Service Connections per Mile 57 58 49 55 65 68 59 

Confidence interval +|- 14 +|- 16 +|- 9 +|- 8 +|- 17 +|- 5 +|- 10 

Average Annual Pipe Replaced in the Past 5 Years (miles) 0 0 1 4 5 7 20 

Confidence interval +|- 0 +|- 0 +|- 0 +|- 5 +|- 2 +|- 2 +|- 11 

Average Cost per Mile of Pipe Replaced in the Past 5 Years (thousands of dollars) 45 107 129 222 252 386 481 

Confidence interval +|- 27 +|- 35 +|- 47 +|- 83 +|- 65 +|- 98 +|- 87 

Observations 147 157 188 132 125 92 155 

Data: Q.19A, Q.20A Notes: *No observations.

Systems reporting zero miles of distribution pipe are included in table.The cost per mile of pipe replaced reported by the 1999 Drinking Water Infrastructure Needs Shigher than reported by the CWS Survey. There are important differences in the information csurveys that account for some of the difference. The main difference is the time covered by thCWS Survey asks about pipe replaced in the past five years, and the Needs Survey asks abopipe in the next 20 years. Sampling error also explains some of the difference; systems that resurveys report similar cost per foot, while systems that did not provide data for both surveys reMost publicly owned systems serving less than 100 people did not replace pipe in the last 5 yeof average cost per mile replaced is based on 3 observations.Costs for public systems serving over 500,000 excludes one project that cost over $50 million included, the mean cost per mile of pipe replaced in the past 5 years is $9.7 million in this cateA public state prison serving 3,301-10,000. people was removed from calculations because of connections per mile.A private system serving 3,301-10,000 people with average cost per mile of $770,000 was droestimate. If included the average cost is $206,000 for private systems of this size.

65
Table 36

Average Size of Distribution System 

By Diameter of Pipe and Ownership

(Miles of Pipe)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100

500

Public Systems

Distribution Mains Less Than 6 Inches 1.5 3.3 21.4 38.5 108.8 136.0 2

Confidence interval +|- 0.7 +|- 1.3 +|- 10.1 +|- 18.9 +|- 57.4 +|- 33.7 +|- 

Distribution Mains 6 to 10 inches 1.2 1.1 3.2 17.0 58.8 122.4 1

Confidence interval +|- 1.5 +|- 0.6 +|- 1.4 +|- 5.1 +|- 26.1 +|- 20.8 +|- 

Distribution Mains Greater Than 10 Inches 0.5 0.1 0.8 4.9 34.1 80.4 1

Confidence interval +|- 0.6 +|- 0.3 +|- 0.4 +|- 1.4 +|- 11.2 +|- 12.8 +|- 

Observations 16 67 160 119 109 82 

Private Systems

Distribution Mains Less Than 6 Inches 1.1 3.5 33.9 190.3 191.0 192.7 3

Confidence interval +|- 0.6 +|- 1.5 +|- 23.5 +|- 188.0 +|- 150.3 +|- 134.0 +|- 

Distribution Mains 6 to 10 inches 0.0 0.1 2.4 23.8 184.6 114.1 2

Confidence interval +|- 0.0 +|- 0.1 +|- 2.0 +|- 11.7 +|- 232.0 +|- 42.8 +|- 

Distribution Mains Greater Than 10 Inches 0.0 0.0 0.3 2.5 14.6 63.6 1

Confidence interval +|- 0.0 +|- 0.0 +|- 0.5 +|- 1.3 +|- 8.8 +|- 24.5 +|- 

Observations 131 90 30 19 17 9 

All Systems

Distribution Mains Less Than 6 Inches 1.1 3.4 23.9 60.8 121.4 141.6 2

Confidence interval +|- 0.6 +|- 1.1 +|- 8.9 +|- 34.1 +|- 53.0 +|- 33.0 +|- 

Distribution Mains 6 to 10 inches 0.1 0.5 3.0 18.0 78.0 121.6 1

Confidence interval +|- 0.1 +|- 0.2 +|- 1.1 +|- 4.5 +|- 41.9 +|- 19.2 +|- 

Distribution Mains Greater Than 10 Inches 0.0 0.1 0.7 4.5 31.1 78.7 1

Confidence interval +|- 0.0 +|- 0.1 +|- 0.4 +|- 1.2 +|- 9.7 +|- 11.9 +|- 

Observations 147 157 190 138 126 91 

Data: Q.19ANotes: Systems reporting zero miles of distribution pipe are included in table.

The estimate for private systems serving greater than 500,000 people is based on 5 systIn private systems serving 50,000-100,000 people, one system with 6,400 miles of pipe wIf included, the average length of six inch pipe for this category is 666 miles. Changes to other categories are insignificant.

66 
Table 37

Distribution System Summary - Percentage of Pipe in Each Age Category 

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Percentage of Pipe that is: 

Less than 40 years old 93.2 92.6 84.5 75.3 68.9 62.5 61.6 Between 40 and 80 years old 6.8 7.4 14.9 20.8 25.4 29.5 31.9 More than 80 years old 0.0 0.0 0.6 3.9 5.7 8.0 6.5 

Observations 103 91 88 57 45 26 35 

Primarily Surface Water Systems

Percentage of Pipe that is: 

Less than 40 years old 67.5 65.4 68.6 73.6 80.0 70.7 55.3 Between 40 and 80 years old 32.0 34.0 23.0 19.6 15.8 22.1 30.8 More than 80 years old 0.5 0.6 8.4 6.8 4.1 7.2 13.9 

Observations 46 52 67 71 72 48 95 

Primarily Purchased Water Systems

Percentage of Pipe that is: 

Less than 40 years old 100.0 84.6 88.3 96.4 92.9 79.7 73.3 Between 40 and 80 years old 0.0 15.4 11.2 3.3 6.4 18.4 23.7 More than 80 years old 0.0 0.0 0.5 0.3 0.7 1.9 3.0 

Observations 6 23 49 26 26 26 44 

All Systems

Percentage of Pipe that is: 

Less than 40 years old 90.6 88.3 85.7 84.3 81.4 70.2 60.9 Between 40 and 80 years old 9.4 11.7 13.3 12.9 15.3 23.4 29.7 More than 80 years old 0.1 0.1 1.0 2.8 3.4 6.4 9.4 

Observations 155 166 204 154 143 100 174 

Data: Q.19A, Q.19BNotes: Table reports the percentage of pipe on average in each age category in the nation. It 

of pipe per system.

67 
Table 38

Distribution System Summary - Percentage of Pipe in Each Age Category 

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Percentage of Pipe that is: 

Less than 40 years old 76.3 81.5 81.1 77.6 76.2 65.2 61.4 Between 40 and 80 years old 23.6 18.3 17.5 18.4 19.7 26.9 29.2 More than 80 years old 0.1 0.1 1.4 4.0 4.2 7.9 9.4 

Observations 18 72 173 135 122 88 160 

Private Systems

Percentage of Pipe that is: 

Less than 40 years old 92.4 92.8 98.7 96.2 95.8 86.6 56.5 Between 40 and 80 years old 7.6 7.2 1.3 3.3 3.1 12.0 34.1 More than 80 years old 0.0 0.0 0.0 0.6 1.1 1.4 9.4 

Observations 137 94 31 19 21 12 14 

All Systems

Percentage of Pipe that is: 

Less than 40 years old 90.6 88.3 85.7 84.3 81.4 70.2 60.9 Between 40 and 80 years old 9.4 11.7 13.3 12.9 15.3 23.4 29.7 More than 80 years old 0.1 0.1 1.0 2.8 3.4 6.4 9.4 

Observations 155 166 204 154 143 100 174 

Data: Q.19A, Q.19BNotes: Table reports the percentage of pipe on average in each age category in the nation. It 

of pipe per system.

68 
Table 39

Service Connections Profile

By Ownership

(Number of Connections)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean Residential Connections 19 110 528 1,856 6,160 16,952 34,193 

Confidence Interval +|- 11 +|- 29 +|- 68 +|- 240 +|- 607 +|- 2,140 +|- 7,334 

Median Residential Connections 20 80 440 1,725 5,367 17,498 30,600 Mean Non-Residential Connections 2 6 35 283 627 1,615 3,443 

Confidence Interval +|- 3 +|- 2 +|- 9 +|- 152 +|- 147 +|- 294 +|- 853 

Median Non-Residential Connections 0 2 15 100 400 1,340 2,371 Observations 18 74 174 145 130 93 175 

Private Systems

Mean Residential Connections 24 105 446 1,609 6,457 20,784 44,192 

Confidence Interval +|- 3 +|- 16 +|- 146 +|- 386 +|- 1,528 +|- 4,576 +|- 6,970 

Median Residential Connections 24 90 390 1,595 4,934 19,618 42,999 Mean Non-Residential Connections 1 1 9 153 631 1,512 4,207 

Confidence Interval +|- 1 +|- 2 +|- 6 +|- 86 +|- 491 +|- 519 +|- 843 

Median Non-Residential Connections 0 0 0 82 230 1,411 3,158 Observations 138 92 31 22 22 16 19 

All Systems

Mean Residential Connections 23 107 512 1,819 6,205 17,434 35,082 

Confidence Interval +|- 3 +|- 14 +|- 60 +|- 212 +|- 566 +|- 1,990 +|- 6,865 

Median Residential Connections 24 86 430 1,668 5,127 17,629 32,324 Mean Non-Residential Connections 1 3 30 264 627 1,603 3,510 

Confidence Interval +|- 1 +|- 2 +|- 7 +|- 130 +|- 146 +|- 267 +|- 793 

Median Non-Residential Connections 0 0 12 100 386 1,401 2,788 Observations 156 166 205 167 152 109 194 

Data: Q.20A

69 
Table 40

Population Served

By Ownership and System Service Population

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean Population Served 61 250 1,440 5,847 21,245 71,091 211,219 

Confidence Interval +|- 19 +|- 38 +|- 163 +|- 407 +|- 1,693 +|- 3,985 +|- 20,488 

Observations 18 76 179 148 138 101 183 

Private Systems

Mean Population Served 53 282 1,216 5,657 21,611 73,327 169,092 

Confidence Interval +|- 6 +|- 34 +|- 304 +|- 801 +|- 5,626 +|- 5,542 +|- 22,632 

Observations 138 95 32 22 23 16 19 

All Systems

Mean Population Served 54 271 1,396 5,819 21,302 71,354 207,583 

Confidence Interval +|- 6 +|- 26 +|- 140 +|- 372 +|- 1,688 +|- 3,586 +|- 19,327 

Observations 156 171 211 170 161 117 202 

Data: Q.20A

70 
Table 41

Annual Deliveries per Customer Service Connection

By Ownership

(Thousands of Gallons)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean Residential Deliveries 119 141 87 250 106 134 144 

Confidence Interval +|- 66 +|- 91 +|- 11 +|- 203 +|- 12 +|- 21 +|- 16 

Median Residential Deliveries 65 70 76 84 87 107 118 Mean Non-Residential Deliveries 288 197 580 860 994 1,095 1,142 

Confidence Interval +|- 637 +|- 128 +|- 508 +|- 304 +|- 516 +|- 396 +|- 297 

Median Non-Residential Deliveries 0 0 125 375 492 679 682 Observations 11 50 127 115 108 79 130 

Private Systems

Mean Residential Deliveries 74 109 91 100 100 112 111 

Confidence Interval +|- 15 +|- 33 +|- 27 +|- 29 +|- 23 +|- 32 +|- 26 

Median Residential Deliveries 67 71 82 83 88 72 84 Mean Non-Residential Deliveries 35 240 256 719 1,348 718 1,315 

Confidence Interval +|- 40 +|- 233 +|- 174 +|- 697 +|- 1,606 +|- 347 +|- 520 

Median Non-Residential Deliveries 0 0 120 341 535 413 915 Observations 85 81 23 18 17 15 16 

All Systems

Mean Residential Deliveries 76 119 88 227 105 131 141 

Confidence Interval +|- 15 +|- 36 +|- 10 +|- 173 +|- 11 +|- 19 +|- 14 

Median Residential Deliveries 65 71 76 84 88 106 117 Mean Non-Residential Deliveries 61 210 536 844 1,040 1,047 1,159 

Confidence Interval +|- 61 +|- 109 +|- 440 +|- 282 +|- 499 +|- 348 +|- 276 

Median Non-Residential Deliveries 0 0 120 364 495 635 695 Observations 96 131 150 133 125 94 146 

Data: Q.4, Q.10, Q.20Notes: Seven public systems with outliers greater than 123 million gallons of water in non-reside

affecting population categories 3,301-10,000 people, 10,000-50,000 people and 100,000-5dropped from the estimate. If included, non-residential deliveries are 5.9 million gallons omillion gallons of water, and 1.1 million gallons of water, respectively.

71 
Table 42

Percentage of Systems that have Cross Connection Control Programs

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Public SystemsPercentage of Systems 15.8 47.8 55.0 83.1 85.1 87.8 92.1 

Confidence Interval +|- 20.4 +|- 21.2 +|- 12.2 +|- 7.4 +|- 9.6 +|- 8.0 +|- 3.1 +

Observations 18 73 177 144 126 98 179 Private SystemsPercentage of Systems 15.9 26.4 39.2 77.8 82.7 94.5 91.7 

Confidence Interval +|- 10.6 +|- 13.3 +|- 20.8 +|- 21.6 +|- 18.9 +|- 9.2 +|- 7.2 +

Observations 137 94 32 20 23 16 19 All SystemsPercentage of Systems 15.9 33.7 51.9 82.4 84.7 88.6 92.0 

Confidence Interval +|- 10.1 +|- 11.4 +|- 11.4 +|- 7.8 +|- 8.6 +|- 7.1 +|- 2.9 +

Observations 155 167 209 164 149 114 198 

Data: Q.22

72 
Table 43

Percentage of Systems that Have a Cross Connection Control Program that is Designed to Prevent Backflow from Reaching

a Publicly Owned Distribution System and Provides Protection within a Customer's Premises. 

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Over 

500,000 

Public SystemsPercentage of Systems 27.9 14.9 22.6 30.3 37.1 31.6 43.3 27.5 

Confidence Interval +|- 45.1 +|- 16.6 +|- 9.3 +|- 10.1 +|- 10.2 +|- 9.8 +|- 12.6 +|- 7.8 

Observations 6 30 101 117 105 86 160 42 Private SystemsPercentage of Systems 0.3 23.3 17.8 28.6 13.4 6.6 19.7 0.0 

Confidence Interval +|- 0.7 +|- 24.7 +|- 23.2 +|- 24.3 +|- 15.4 +|- 11.0 +|- 13.7 +|- 0.0 

Observations 19 24 13 15 19 13 17 5 

All SystemsPercentage of Systems 1.9 19.3 21.8 30.1 33.2 28.7 41.2 24.8 

Confidence Interval +|- 2.8 +|- 17.0 +|- 9.4 +|- 9.4 +|- 9.1 +|- 8.8 +|- 11.4 +|- 7.1 

Observations 25 54 114 132 124 99 177 47 

Data: Q.23Definitions: These systems have a Containment and Isolation program. This is often referred to as providing protec

to the tap. Containment-only programs are designed to prevent backflow from reaching a publicly ownedistribution system, but do not provide protection within the premises. This is often referred to as providprotection up to the meter.

73 
Table 44

Percentage of Systems With Each Element in their Cross Connection Control Programs

By Water System Service Population

System Service Population Category

Cross Connection Control Program Element

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

5

Right of entry 85.7 93.3 98.6 93.1 89.6 82.8 85.2 

Confidence Interval +|- 0.0 +|- 7.7 +|- 1.5 +|- 4.5 +|- 5.6 +|- 8.3 +|- 4.6 

Surveys/inspections to identify cross connections within the system/facility 91.2 90.4 97.8 90.5 87.6 84.7 90.7 

Confidence Interval +|- 13.2 +|- 9.2 +|- 2.1 +|- 5.6 +|- 6.7 +|- 8.0 +|- 3.2 

Policy specifying which service connections must be equipped with backflow prevention device/assemblies 91.4 97.0 98.4 95.9 93.7 90.0 97.1 

Confidence Interval +|- 13.2 +|- 3.9 +|- 2.1 +|- 3.8 +|- 5.1 +|- 7.2 +|- 1.7 

Enforcement authority to install devices/assemblies 86.2 97.7 97.7 84.5 90.8 80.6 89.5 

Confidence Interval +|- 14.7 +|- 3.4 +|- 2.1 +|- 7.2 +|- 5.0 +|- 7.8 +|- 4.0 

Enforcement authority to test assemblies 85.7 98.0 94.2 85.9 84.5 75.2 76.9 

Confidence Interval +|- 15.1 +|- 3.4 +|- 6.7 +|- 6.6 +|- 6.8 +|- 11.9 +|- 16.0 

Penalties for non-compliance with ordinance 78.6 91.5 90.3 74.6 80.3 76.2 71.2 

Confidence Interval +|- 17.7 +|- 7.9 +|- 8.0 +|- 9.3 +|- 7.5 +|- 8.3 +|- 15.0 

Public education programs 68.2 49.2 47.3 52.0 39.6 48.8 51.4 

Confidence Interval +|- 23.9 +|- 19.7 +|- 17.3 +|- 11.8 +|- 9.4 +|- 10.8 +|- 12.6 

Training/certification of testers and inspectors 82.3 62.0 55.4 63.1 62.3 71.6 64.8 

Confidence Interval +|- 19.5 +|- 18.9 +|- 17.3 +|- 9.9 +|- 9.4 +|- 9.2 +|- 14.2 

Observations 24 51 113 129 126 99 174 Data: Q.24

74 
Table 45

Mean Percentage of Backflow Prevention Assemblies that are Tested and Fail Annually During Inspection

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ov

500,0

Public SystemsPercentage of Systems 3.0 0.1 0.7 4.1 6.2 6.1 8.9 10

Confidence Interval +|- 6.4 +|- 0.1 +|- 1.0 +|- 2.1 +|- 1.7 +|- 1.8 +|- 1.2 +|- 2

Observations 3 20 80 72 83 60 127 Private SystemsPercentage of Systems 0.1 0.1 0.2 6.5 6.4 3.4 6.8 4

Confidence Interval +|- 0.1 +|- 0.1 +|- 0.4 +|- 6.8 +|- 3.0 +|- 1.8 +|- 2.5 +|- 2

Observations 13 18 12 12 16 9 14 All SystemsPercentage of Systems 0.1 0.1 0.7 4.5 6.2 5.8 8.7 9

Confidence Interval +|- 0.2 +|- 0.1 +|- 0.9 +|- 2.1 +|- 1.5 +|- 1.6 +|- 1.1 +|- 2

Observations 16 38 92 84 99 69 141 

Data: Q.25

75 
Table 46

Total Revenue

By Primary Source of Water

(Thousands of Dollars)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

500

Primarily Ground Water Systems

Mean 5 23 146 622 2,179 7,878 14,013 75

Confidence Interval +|- 2 +|- 6 +|- 31 +|- 118 +|- 431 +|- 982 +|- 7,219 +|- 13

Median 2 20 107 605 1,862 7,126 12,670 86

% not charging directly for water 43 32 4 5 6 0 0 

Confidence Interval +|- 17 +|- 13 +|- 4 +|- 7 +|- 8 +|- 0 +|- 0 

Observations 86 80 89 62 44 27 40 

Primarily Surface Water Systems

Mean 17 55 350 961 3,133 8,027 23,839 151

Confidence Interval +|- 10 +|- 20 +|- 85 +|- 147 +|- 502 +|- 1,613 +|- 2,122 +|- 31

Median 10 48 269 856 2,356 6,559 19,198 89% not charging directly for water 22 5 3 1 0 2 0 

Confidence Interval +|- 26 +|- 6 +|- 3 +|- 3 +|- 0 +|- 3 +|- 0 

Observations 41 50 68 72 78 53 106 

Primarily Purchased Water Systems

Mean 2 30 222 971 3,534 11,716 22,869 175

Confidence Interval +|- 5 +|- 10 +|- 55 +|- 353 +|- 917 +|- 2,985 +|- 2,672 +|- 50

Median 0 19 166 751 2,473 8,899 20,346 115

% not charging directly for water 90 1 0 4 0 0 0 

Confidence Interval +|- 23 +|- 2 +|- 0 +|- 9 +|- 0 +|- 0 +|- 0 

Observations 6 20 48 26 27 27 45 

All Systems

Mean 6 26 185 760 2,817 8,953 19,961 147

Confidence Interval +|- 2 +|- 5 +|- 26 +|- 111 +|- 338 +|- 1,181 +|- 3,938 +|- 23

Median 2 20 144 648 2,302 7,313 16,187 99

% not charging directly for water 42 26 3 4 2 1 0 

Confidence Interval +|- 16 +|- 11 +|- 3 +|- 5 +|- 3 +|- 1 +|- 0 

Observations 133 150 205 160 149 107 191 

Data: Q.26CNotes: Two ground water systems serving less than 100 people with large non residential sales are dropp

systems are included then revenues for ground water systems systems serving 100 or less are $1average revenues for all systems of this size are $6,000

76 
Table 47

Total Revenue

By Ownership

(Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean 14 33 186 756 2,811 8,857 19,608 

Confidence Interval +|- 8 +|- 9 +|- 31 +|- 117 +|- 340 +|- 1,278 +|- 4,169 +

Median 10 26 134 653 2,302 7,126 16,444 % not charging directly for water 20 5 2 4 1 0 0 

Confidence Interval +|- 33 +|- 6 +|- 2 +|- 5 +|- 2 +|- 0 +|- 0 

Observations 13 72 176 142 132 95 176 

Private Systems

Mean 6 21 178 792 2,858 9,855 24,347 

Confidence Interval +|- 2 +|- 7 +|- 56 +|- 302 +|- 1,279 +|- 2,331 +|- 5,670 +

Median 2 17 194 633 2,397 10,133 15,970 % not charging directly for water 43 39 6 8 12 7 0 

Confidence Interval +|- 16 +|- 15 +|- 11 +|- 14 +|- 21 +|- 12 +|- 0 

Observations 120 78 29 18 17 12 15 

All Systems

Mean 6 26 185 760 2,817 8,953 19,961 

Confidence Interval +|- 2 +|- 5 +|- 26 +|- 111 +|- 338 +|- 1,181 +|- 3,938 +

Median 2 20 144 648 2,302 7,313 16,187 % not charging directly for water 42 26 3 4 2 1 0 

Confidence Interval +|- 16 +|- 11 +|- 3 +|- 5 +|- 3 +|- 1 +|- 0 

Observations 133 150 205 160 149 107 191 

Data: Q.26CNotes: Two public systems serving less than 100 people with large non residential sales are dropped

are included then revenues for public systems systems serving 100 or less are $273,300 and all systems of this size are $17,000.Refer to the next table for additional detail on private systems.

77 
Table 48

Total Revenue

Private Systems, by Type

(Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

All Small 

Systems

Private Systems

Mean 9.9 34.0 191.0 49.9

Confidence Interval +|- 3.5 +|- 6.7 +|- 55.2 +|- 15.8

Median 6.0 25.8 194.3 21.3% not charging directly for water 11.0 0.3 0.0 4.9

Confidence Interval +|- 10.5 +|- 0.4 +|- 0.0 +|- 4.6

Observations 71 48 26 145

Ancillary Systems

Mean 0.7 0.8 6.6 0.9

Confidence Interval +|- 0.9 +|- 1.1 +|- 16.3 +|- 0.7

Median 0.0 0.0 0.0 0.0% not charging directly for water 83.3 92.7 92.0 87.6

Confidence Interval +|- 18.6 +|- 9.8 +|- 19.7 +|- 11.0

Observations 49 30 3 82

All Private Systems

Mean 5.8 21.0 178.4 31.2

Confidence Interval +|- 2.4 +|- 6.7 +|- 55.6 +|- 10.5

Median 2.3 16.7 194.3 6.0% not charging directly for water 42.9 39.1 6.3 37.4

Confidence Interval +|- 16.3 +|- 14.8 +|- 11.2 +|- 10.3

Observations 120 78 29 227

Data: Q.26C

78 
Table 49

Total Revenue for Systems Reporting Positive Revenue and Expenses

By Ownership

(Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Over 

500,000 

Public Systems

Mean 18 35 191 778 2,784 8,913 21,773 150,214 

Confidence interval +|- 7 +|- 9 +|- 32 +|- 122 +|- 335 +|- 1,317 +|- 1,837 +|- 27,300 

Median 10 26 134 653 2,302 7,126 16,444 89,897 Observations 11 64 169 132 124 91 169 47 

Private Systems

Mean 10 37 191 850 3,477 9,783 23,675 115,584 

Confidence interval +|- 4 +|- 7 +|- 57 +|- 310 +|- 1,331 +|- 2,185 +|- 5,618 +|- 5,613 

Median 2 17 194 633 2,397 10,133 15,970 122,075 Observations 66 43 26 16 14 9 13 3 

All Systems

Mean 10 36 191 786 2,857 8,982 21,915 148,186 

Confidence interval +|- 3 +|- 6 +|- 27 +|- 115 +|- 337 +|- 1,228 +|- 1,754 +|- 25,684 

50th Percentile 2 20 144 648 2,302 7,313 16,187 99,807 Observations 77 107 195 148 138 100 182 50 

Data: Q.26CNotes: Table reports systems who reported both positive revenue and positive expenses only.

One public system serving less than 100 people with revenue of $1.8 million was dropped.If included, the mean revenue for public systems serving less than 100 people is $305,427.A private system serving 100 or less with revenue of $6,000 was dropped from the estimate.If included, revenue for this category is $5,795. 

79 
Table 50

Revenue Breakdown

By Ownership

(Percentage of Systems with Each Type of Revenue)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Public Systems

Water Sales 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Confidence Interval +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +

Water-Related Operations 26.3 36.9 58.1 88.7 84.1 79.9 72.4 

Confidence Interval +|- 33.5 +|- 14.4 +|- 14.4 +|- 7.0 +|- 7.2 +|- 9.9 +|- 15.7 +

General Fund 1.0 5.9 7.2 6.1 14.4 8.4 11.3 

Confidence Interval +|- 2.2 +|- 7.2 +|- 7.1 +|- 4.6 +|- 7.1 +|- 4.7 +|- 4.0 +

Other Revenue Sources 20.6 50.4 72.0 73.8 85.0 79.7 73.8 

Confidence Interval +|- 30.7 +|- 18.0 +|- 10.6 +|- 12.0 +|- 6.9 +|- 10.6 +|- 16.0 +

Private Systems

Water Sales 100.0 99.0 100.0 100.0 100.0 100.0 100.0 

Confidence Interval +|- 0.0 +|- 2.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +

Water-Related Operations 18.9 32.7 35.0 72.0 74.0 35.2 32.0 

Confidence Interval +|- 12.7 +|- 17.9 +|- 21.4 +|- 24.4 +|- 23.3 +|- 24.9 +|- 17.4 +|- 

Other Revenue Sources 10.1 31.9 52.9 55.3 61.0 70.6 70.6 

Confidence Interval +|- 7.9 +|- 17.7 +|- 22.1 +|- 28.4 +|- 26.0 +|- 24.5 +|- 20.4 +|- 

All Systems

Water Sales 100.0 99.5 100.0 100.0 100.0 100.0 100.0 

Confidence Interval +|- 0.0 +|- 1.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +|- 0.0 +

Water-Related Operations 19.4 34.8 53.9 87.0 82.9 76.1 69.3 

Confidence Interval +|- 12.0 +|- 11.5 +|- 11.8 +|- 6.8 +|- 7.0 +|- 9.5 +|- 14.2 +

General Fund 0.1 2.9 5.9 5.4 12.6 7.7 10.4 

Confidence Interval +|- 0.1 +|- 3.5 +|- 5.9 +|- 4.1 +|- 6.3 +|- 4.4 +|- 3.6 +

Other Revenue Sources 10.8 41.0 68.5 71.9 82.0 78.9 73.5 

Confidence Interval +|- 8.4 +|- 14.2 +|- 9.2 +|- 11.1 +|- 7.0 +|- 9.9 +|- 14.8 +

Data: Q.26Notes: Systems have more than one type of revenue; therefore column totals may not sum to 100.

Table includes systems with positive revenue from water sales and water related operations only.

80 
Table 51

Revenue Breakdown

By Ownership

(Percentage of Revenue By Type of Revenue Source)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Ov

500,0

Public Systems

Water Sales 85.0 89.7 90.9 89.1 88.5 87.7 88.9 86Confidence Interval +|- 21.5 +|- 4.8 +|- 2.4 +|- 2.6 +|- 2.1 +|- 2.5 +|- 2.9 +|- 2

Water-Related Operations 8.0 3.2 2.0 5.3 5.6 5.6 4.6 4Confidence Interval +|- 13.5 +|- 2.8 +|- 0.9 +|- 2.0 +|- 1.9 +|- 2.1 +|- 1.3 +|- 1General Fund 0.3 0.9 1.4 1.5 0.6 0.9 0.9 1Confidence Interval +|- 0.7 +|- 1.1 +|- 1.6 +|- 1.6 +|- 0.4 +|- 0.8 +|- 0.5 +|- 0

Other Revenue Sources 6.6 6.2 6.0 4.2 5.4 5.9 5.7 8Confidence Interval +|- 9.5 +|- 4.7 +|- 1.5 +|- 1.4 +|- 1.2 +|- 1.7 +|- 1.8 +|- 1

Private Systems

Water Sales 96.6 95.4 92.6 92.5 90.4 98.3 97.8 96Confidence Interval +|- 3.3 +|- 2.8 +|- 6.2 +|- 3.5 +|- 5.4 +|- 1.2 +|- 1.2 +|- 2

Water-Related Operations 2.8 2.0 4.0 4.9 4.7 0.8 0.9 3Confidence Interval +|- 3.2 +|- 1.7 +|- 5.6 +|- 2.6 +|- 2.8 +|- 1.1 +|- 0.7 +|- 2Other Revenue Sources 0.6 2.5 3.5 3.0 4.7 1.1 1.4 0Confidence Interval +|- 0.6 +|- 2.2 +|- 3.3 +|- 2.2 +|- 4.6 +|- 0.8 +|- 1.0 +|- 0

All Systems

Water Sales 95.9 92.7 91.2 89.5 88.7 88.7 89.6 87Confidence Interval +|- 3.4 +|- 3.1 +|- 2.3 +|- 2.4 +|- 2.0 +|- 2.4 +|- 2.6 +|- 2

Water-Related Operations 3.2 2.6 2.4 5.2 5.5 5.2 4.3 4Confidence Interval +|- 3.1 +|- 1.6 +|- 1.2 +|- 1.8 +|- 1.7 +|- 2.0 +|- 1.2 +|- 1General Fund 0.0 0.3 1.1 1.2 0.5 0.8 0.8 0Confidence Interval +|- 0.0 +|- 0.4 +|- 1.2 +|- 1.4 +|- 0.3 +|- 0.7 +|- 0.5 +|- 0Other Revenue Sources 1.0 4.3 5.5 4.1 5.4 5.5 5.3 7Confidence Interval +|- 0.9 +|- 2.8 +|- 1.4 +|- 1.3 +|- 1.2 +|- 1.5 +|- 1.7 +|- 1

Data: Q.26

81 
Table 52

Water Sales Revenue Profile

By Ownership

(Percentage of Revenue from Each Customer Category)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Public Systems

Residential 91.3 85.8 85.9 72.3 64.3 57.5 51.5 

Confidence Interval +|- 14.7 +|- 9.0 +|- 4.6 +|- 5.5 +|- 5.1 +|- 7.7 +|- 3.8 +

Non-Residential 8.7 14.8 11.6 21.9 26.9 25.5 25.9 

Confidence Interval +|- 14.7 +|- 10.0 +|- 3.6 +|- 5.5 +|- 4.2 +|- 4.2 +|- 2.8 +

Wholesale 0.0 1.4 1.8 4.7 8.2 14.8 18.7 

Confidence Interval +|- 0.0 +|- 2.5 +|- 1.7 +|- 2.8 +|- 3.3 +|- 9.0 +|- 6.6 +

Observations 12 51 128 102 111 80 154 

Private Systems

Residential 99.0 98.2 91.2 85.9 79.6 74.3 59.6 

Confidence Interval +|- 1.2 +|- 2.5 +|- 10.2 +|- 7.4 +|- 11.0 +|- 10.8 +|- 10.1 +

Non-Residential 1.0 0.6 8.2 9.0 13.0 17.3 32.3 

Confidence Interval +|- 1.1 +|- 0.6 +|- 9.7 +|- 5.7 +|- 7.7 +|- 6.0 +|- 7.8 +

Wholesale 0.2 1.2 0.1 3.6 6.0 13.4 8.2 

Confidence Interval +|- 0.4 +|- 2.4 +|- 0.2 +|- 4.5 +|- 7.9 +|- 13.9 +|- 6.7 +

Observations 67 47 23 16 13 9 14 

All Systems

Residential 98.5 93.0 86.9 74.2 66.0 59.0 52.2 

Confidence Interval +|- 1.3 +|- 5.1 +|- 4.0 +|- 5.1 +|- 4.6 +|- 7.2 +|- 3.6 +

Non-Residential 1.4 7.0 10.9 20.0 25.4 24.7 26.5 

Confidence Interval +|- 1.3 +|- 5.0 +|- 3.2 +|- 4.8 +|- 3.9 +|- 3.8 +|- 2.7 +

Wholesale 0.2 1.3 1.5 4.5 7.9 14.7 18.0 

Confidence Interval +|- 0.4 +|- 2.4 +|- 1.5 +|- 2.5 +|- 3.0 +|- 8.3 +|- 6.1 +

Observations 79 98 151 118 124 89 168 

Data: Q.26ANotes: Column totals may not sum to 100 due to rounding.

82 
Table 53

Total Revenue

By Ownership

(Dollars per 1,000 Gallons Sold)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean 4.47 3.28 3.51 2.46 2.57 2.19 1.72 

Confidence Interval +|- 1.42 +|- 0.75 +|- 0.52 +|- 0.32 +|- 0.48 +|- 0.23 +|- 0.36 

Median 5.10 2.32 2.88 2.14 2.23 1.78 1.81 Observations 9 66 167 139 130 95 174 

Private Systems

Mean 4.39 3.76 4.50 3.90 2.88 2.84 2.50 

Confidence Interval +|- 1.22 +|- 0.77 +|- 1.03 +|- 0.94 +|- 0.54 +|- 0.57 +|- 0.32 

Median 1.80 2.02 3.84 3.41 2.70 3.10 2.48 Observations 58 48 25 17 16 11 15 

All Systems

Mean 4.39 3.53 3.67 2.62 2.61 2.25 1.78 

Confidence Interval +|- 1.17 +|- 0.54 +|- 0.48 +|- 0.32 +|- 0.42 +|- 0.22 +|- 0.34 

Median 1.99 2.17 3.08 2.19 2.32 1.84 1.82 Observations 67 114 192 156 146 106 189 

Data: Q.26C, Q.5Notes: Includes wholesale deliveries and unaccounted for water.

Outliers were dropped from public systems serving 25-100 and 501-3,300 and private systems serving 500-3,301. If included in the estimate, these cells are 6.46, 3.59, 4.04, and 5.43, respectively.

83 
Table 54

Water Sales Revenue

By Ownership

(Dollars per 1,000 Gallons Sold)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean 3.89 3.09 3.13 2.10 2.23 1.84 1.46 

Confidence Interval +|- 1.74 +|- 0.74 +|- 0.43 +|- 0.25 +|- 0.44 +|- 0.17 +|- 0.30 

Median 5.10 2.32 2.62 1.85 1.85 1.61 1.59 Observations 9 68 169 137 128 94 174 

Private Systems

Mean 4.31 3.88 3.99 3.39 2.59 2.78 2.46 

Confidence Interval +|- 1.19 +|- 0.94 +|- 0.73 +|- 0.84 +|- 0.50 +|- 0.56 +|- 0.32 

Median 1.99 2.01 3.84 3.12 2.38 2.31 2.47 Observations 59 48 25 18 16 11 15 

All Systems

Mean 4.30 3.50 3.27 2.26 2.27 1.92 1.53 

Confidence Interval +|- 1.15 +|- 0.64 +|- 0.39 +|- 0.27 +|- 0.39 +|- 0.18 +|- 0.30 

Median 1.99 2.24 2.84 2.04 1.95 1.65 1.64 Observations 68 116 194 155 144 105 189 

Data: Q.26A, Q.5Notes: Outliers were dropped from public systems serving 25-100 and 501-3,300 and private systems serving 

500-3,301. If included in the estimate, these cells are 6.06, 3.25, 5.54, and 4.93, respectively.

84 
Table 55

Water Sales Revenue--Customer Breakdown

By Ownership

(Dollars per 1,000 Gallons Sold)

System Service Population Category

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Residential

Mean 3.25 3.39 3.66 2.78 2.83 2.48 2.08 

Confidence Interval +|- 2.70 +|- 0.96 +|- 0.69 +|- 0.45 +|- 0.58 +|- 0.23 +|- 0.10 

Median 5.10 3.43 3.03 2.46 2.72 2.49 2.02 Observations 8 48 110 95 94 70 122 

Non-Residential

Mean 1.82 3.03 4.23 3.05 2.86 2.43 3.06 

Confidence Interval +|- 0.58 +|- 1.56 +|- 1.48 +|- 1.12 +|- 0.84 +|- 0.46 +|- 1.03 

Median 2.08 2.84 2.79 1.92 2.05 1.90 1.86 Observations 2 9 70 78 90 69 121 

Wholesale

Mean * * 1.93 1.67 1.70 1.89 1.54 

Confidence Interval * * +|- 0.86 +|- 0.50 +|- 0.59 +|- 0.40 +|- 0.24 

Median * * 1.96 1.65 1.24 1.56 1.45 Observations 0 0 18 32 58 48 107 

Private Systems

Residential

Mean 2.86 2.64 4.29 3.97 2.78 3.72 3.12 

Confidence Interval +|- 1.12 +|- 1.03 +|- 0.79 +|- 1.84 +|- 1.09 +|- 0.95 +|- 0.58 

Median 2.00 2.14 4.82 3.19 2.75 3.44 3.26 Observations 84 68 20 15 12 10 12 

Non-Residential

Mean 0.00 2.93 6.28 2.05 3.01 3.38 2.36 

Confidence Interval +|- 0.00 +|- 0.39 +|- 4.63 +|- 1.34 +|- 2.49 +|- 2.03 +|- 0.56 

Median 0.00 2.81 5.02 1.61 1.83 2.57 2.35 Observations 4 3 8 10 10 12 12 

Wholesale

Mean 1.09 * 1.16 1.77 2.15 2.47 1.64 

Confidence Interval +|- 1.35 * +|- 1.54 +|- 0.36 +|- 1.18 +|- 0.76 +|- 0.36 

Median 1.59 * 2.22 1.67 2.26 2.00 1.28 Observations 2 0 2 3 6 7 9 

(C

Ownership Type

85 
Table 55 (Cont.)

Water Sales Revenue--Customer Breakdown

By Ownership

(Dollars per 1,000 Gallons Sold)

System Service Population Category

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

All Systems

Residential

Mean 2.87 2.89 3.78 2.95 2.83 2.63 2.18 

Confidence Interval +|- 1.09 +|- 0.76 +|- 0.58 +|- 0.54 +|- 0.52 +|- 0.24 +|- 0.11 

Median 2.34 2.79 3.27 2.47 2.72 2.60 2.05 Observations 92 116 130 110 106 80 134 

Non-Residential

Mean 0.04 3.01 4.53 2.93 2.88 2.56 2.99 

Confidence Interval +|- 0.09 +|- 1.28 +|- 1.45 +|- 0.99 +|- 0.79 +|- 0.49 +|- 0.93 

Median 0.00 2.81 2.79 1.91 2.05 1.93 1.86 Observations 6 12 78 88 100 81 133 

Wholesale

Mean 1.09 * 1.92 1.68 1.74 1.95 1.55 

Confidence Interval +|- 1.35 * +|- 0.84 +|- 0.46 +|- 0.55 +|- 0.37 +|- 0.23 

Median 1.59 * 1.96 1.67 1.32 1.67 1.43 Observations 92 116 130 110 106 80 134 

 Q 26 Q.26Notes: *No data collected for these systems. 

Wholesale revenue for public systems serving 101-500 people contained only 1 county cluster of systecalculate the design-based 95% confidence interval, this cluster was moved to the 501-3,301 stratum fOutliers were dropped from residential revenue for public systems serving 25-100 and 501-3,300, residprivate systems serving 25-100 and 500-3,301, non-residential revenue for public systems serving 3,350,001-100,000, and wholesale systems serving 50,001-100,000 and 100,001-500,000. If included in these cells are 5.75, 3.75, 3.77, 5.36, 4.90, 3.02, 2.86, and 32.47 respectively.

Ownership Type

86 
Table 56

Residential Revenue per Connection

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean Residential Revenues per Connection 363 258 272 238 255 276 286 

Confidence interval +|- 239 +|- 60 +|- 35 +|- 33 +|- 32 +|- 34 +|- 23 

Median Residential Revenues per Connection 329 220 237 217 227 261 260 Observations 13 54 128 101 103 72 130 

Private Systems

Mean Residential Revenues per Connection 230 218 358 341 320 439 333 

Confidence interval +|- 101 +|- 76 +|- 142 +|- 111 +|- 85 +|- 145 +|- 75 

Median Residential Revenues per Connection 172 250 333 318 287 439 314 Observations 113 72 24 16 12 10 14 

All Systems

Mean Residential Revenues per Connection 235 232 289 253 262 295 290 

Confidence interval +|- 98 +|- 54 +|- 42 +|- 34 +|- 30 +|- 36 +|- 23 

Median Residential Revenues per Connection 175 235 258 228 237 273 263 Observations 126 126 152 117 115 82 144 

Data: Q.26A2, Q.20AbNotes: One public system serving 25-100 people was dropped from the estimate. If included, residen

connection are $431.Two private systems serving 25-100 people were dropped from the estimate. If included, residper connection connection are $423.

(Dollars)

87 
Table 57

Residential Revenue per Connection

Private Systems, by Type

 (Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

Small 

Systems

Private Systems

Mean Residential Revenues per Connection 382 319 383 356

Confidence interval +|- 124 +|- 70 +|- 128 +|- 64

Median Residential Revenues per Connection 277 291 336 291Observations 67 47 23 137

Ancillary Systems

Mean Residential Revenues per Connection 20 12 0 17

Confidence interval +|- 33 +|- 17 +|- 0 +|- 21

Median Residential Revenues per Connection 0 0 0 0Observations 46 25 1 72

All Systems

Mean Residential Revenues per Connection 230 218 358 239

Confidence interval +|- 94 +|- 71 +|- 132 +|- 56

Median Residential Revenues per Connection 149 250 333 222Observations 113 72 24 209

Data: Q.28Notes: Two private systems serving 25-100 people

were dropped from the estimate. If included,mean residential revenues per connectionare $706 for this category.

88 
Table 58

Residential Rate Structure and Billing Profile

By Ownership

(Percentage of Systems with Each Structure)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Public Systems Metered Charges

Uniform Rate 11.6 52.2 52.9 55.1 55.1 45.4 51.1 Declining Block Rate 0.0 14.1 29.0 31.4 32.1 21.7 21.0 Increasing Block Rate 2.6 10.2 14.3 12.4 16.7 29.3 24.1 Seasonal Rate 0.0 0.0 0.4 2.3 0.6 3.6 8.9 

 Unmetered Charges

Separate Flat Fee for Water 41.0 21.9 6.3 21.7 23.8 24.5 25.7 Combined Flat Fee for Water and Other Services 31.5 0.0 0.1 3.3 3.7 7.9 2.3 

 Other billing methods 3.0 0.1 1.4 4.5 2.0 2.7 3.3  Observations 18 76 179 148 138 101 183 Private Systems

 Metered Charges

Uniform Rate 25.3 28.2 47.8 39.2 44.8 70.4 48.6 Declining Block Rate 0.0 4.7 19.6 42.6 44.7 29.6 33.3 Increasing Block Rate 3.4 3.6 17.5 14.5 9.7 0.0 13.9 Seasonal Rate 0.0 0.1 0.0 0.0 2.9 0.0 0.0 

 Unmetered Charges

Separate Flat Fee for Water 16.5 17.0 16.4 2.5 33.8 22.3 9.0 Combined Flat Fee for Water and Other Services 17.1 10.9 0.1 1.5 9.7 0.0 0.0 

 Other billing methods 1.7 0.5 0.0 0.0 0.0 0.0 0.0  Observations 138 95 32 22 23 16 19 

(Contin

89 
Table 58 (Cont.)

Residential Rate Structure and Billing Profile

By Ownership

(Percentage of Systems with Each Structure)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

All Systems

 Metered Charges

Uniform Rate 24.5 36.6 52.0 52.7 53.7 48.4 50.9 Declining Block Rate 0.0 8.0 27.3 33.0 33.8 22.6 22.1 Increasing Block Rate 3.4 5.9 14.9 12.7 15.7 25.8 23.2 Seasonal Rate 0.0 0.0 0.3 1.9 0.9 3.2 8.2 

 Unmetered Charges

Separate Flat Fee for Water 17.9 18.7 8.1 18.9 25.2 24.3 24.2 Combined Flat Fee for Water and Other Services 17.9 7.1 0.1 3.0 4.5 7.0 2.1 

 Other billing methods 1.8 0.4 1.1 3.9 1.7 2.4 3.0  Observations 156 171 211 170 161 117 202 Data: Q.29Notes: These rate structures only apply to residential customers.

Column totals may not sum to 100.

90 
Table 59

Total Expenses

By Primary Source of Water

(Thousands of Dollars)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Mean 7 25 133 568 2,147 6,779 18,175 

Confidence interval +|- 3 +|- 5 +|- 30 +|- 110 +|- 479 +|- 751 +|- 2,899 +|

Median 3 18 99 501 1,705 6,969 13,412 Observations 91 82 86 60 43 26 36 

Primarily Surface Water Systems

Mean 19 72 313 980 2,714 6,548 18,604 

Confidence interval +|- 8 +|- 21 +|- 62 +|- 311 +|- 434 +|- 1,297 +|- 1,657 +|

Median 21 54 279 720 2,356 5,747 15,048 Observations 37 45 68 69 73 52 104 

Primarily Purchased Water Systems

Mean 7 28 208 816 3,704 10,535 18,932 

Confidence interval +|- 7 +|- 10 +|- 49 +|- 300 +|- 1,260 +|- 2,769 +|- 2,233 +|

Median 2 18 170 603 2,426 8,721 17,992 Observations 6 20 47 22 24 25 43 

All Systems

Mean 7 28 169 699 2,673 7,617 18,561 

Confidence interval +|- 3 +|- 5 +|- 25 +|- 115 +|- 385 +|- 1,020 +|- 1,278 +|

Median 3 19 128 588 2,299 6,969 14,969 Observations 134 147 201 151 140 103 183 

Data: Q.7, Q.31Notes: One system ground water system serving 25-100 with expenses of $406,808 was dropped fro

included, the category is $8,900.

91 
Table 60

Total Expenses

By Ownership

(Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean 15 36 167 704 2,675 7,630 18,408 

Confidence interval +|- 10 +|- 9 +|- 29 +|- 126 +|- 406 +|- 1,101 +|- 1,309 +

Median 13 30 110 603 2,299 6,469 14,031 Observations 13 69 173 133 125 94 170 

Private Systems

Mean 7 23 180 667 2,664 7,470 20,466 

Confidence interval +|- 3 +|- 6 +|- 50 +|- 246 +|- 1,216 +|- 1,393 +|- 5,319 +

Median 3 14 173 495 1,855 7,366 15,572 Observations 121 78 28 18 15 9 13 

All Systems

Mean 7 28 169 699 2,673 7,617 18,561 

Confidence interval +|- 3 +|- 5 +|- 25 +|- 115 +|- 385 +|- 1,020 +|- 1,278 +

Median 3 19 128 588 2,299 6,969 14,969 Observations 134 147 201 151 140 103 183 

Data: Q.31Notes: A public system serving 100 or less that has expenses of over $400,000 due to large commerc

excluded. If included, expenses for this category are $66,000.

92 
Table 61

Total Expenses for Systems Reporting Positive Revenues and Expenses

By Ownership

(Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Over 

500,000 

Public Systems

Mean 15 36 168 706 2,695 7,685 18,497 131,490 

Confidence interval +|- 11 +|- 10 +|- 29 +|- 127 +|- 409 +|- 1,121 +|- 1,317 +|- 23,716 

Median 13 30 110 603 2,299 6,469 14,031 80,727 Observations 11 64 169 132 124 91 169 47 

Private Systems

Mean 10 32 180 736 3,034 7,470 20,466 94,419 

Confidence interval +|- 5 +|- 8 +|- 51 +|- 273 +|- 1,190 +|- 1,394 +|- 5,320 +|- 6,019 

Median 3 14 173 495 1,855 7,366 15,572 90,830 Observations 66 43 26 16 14 9 13 3 

All Systems

Mean 10 34 170 709 2,731 7,668 18,644 129,320 

Confidence interval +|- 5 +|- 6 +|- 26 +|- 118 +|- 388 +|- 1,036 +|- 1,285 +|- 22,379 

Median 3 19 128 588 2,299 6,969 14,969 82,283 Observations 77 107 195 148 138 100 182 50 

Data: Q.31Notes: Table reports systems who reported both positive revenues and positive expenses only.

A public system serving 100 or less that has expenses of over $400,000 due to large commercial sales isexcluded. If included, expenses for this category are $76,000. A private system serving 100 or less that has expenses of $400 has been dropped from the estimate.If included, expenses for this category are $9,000. 

93 
Table 62

Expense Breakdown By Major Categories

By Ownership

(As Percentage of Total Expenses)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Employee Expenses 34.2 31.6 32.4 33.0 30.1 27.7 34.1 

Confidence interval +|- 13.2 +|- 7.7 +|- 4.8 +|- 2.8 +|- 3.2 +|- 2.3 +|- 10.9 

Routine Operating Expenses 44.9 52.5 52.2 46.4 44.0 45.8 38.5 

Confidence interval +|- 15.7 +|- 7.6 +|- 4.4 +|- 4.6 +|- 5.0 +|- 3.8 +|- 5.8 

Debt Service Expenses: 16.2 10.7 12.2 15.8 20.5 20.7 16.8 

Confidence interval +|- 17.6 +|- 3.4 +|- 3.1 +|- 4.4 +|- 5.2 +|- 3.4 +|- 3.9 

Other Expenses: 4.7 5.7 3.4 5.3 5.8 5.7 10.8 

Confidence interval +|- 7.4 +|- 4.9 +|- 2.8 +|- 2.9 +|- 2.4 +|- 2.6 +|- 4.9 

Private Systems

Employee Expenses 27.7 28.6 31.8 39.9 34.1 27.2 22.7 

Confidence interval +|- 8.0 +|- 9.3 +|- 10.5 +|- 19.4 +|- 11.7 +|- 6.7 +|- 3.8 

Routine Operating Expenses 71.7 68.6 52.6 56.1 50.8 62.0 63.2 

Confidence interval +|- 8.0 +|- 8.9 +|- 9.3 +|- 18.8 +|- 12.6 +|- 12.5 +|- 10.6 

Debt Service Expenses: 1.5 2.6 9.9 3.8 8.8 8.2 8.4 

Confidence interval +|- 2.0 +|- 1.7 +|- 6.4 +|- 3.4 +|- 5.3 +|- 6.3 +|- 3.0 

Other Expenses: 1.1 0.9 6.0 3.0 7.8 4.1 6.5 

Confidence interval +|- 1.4 +|- 1.6 +|- 9.6 +|- 4.1 +|- 9.6 +|- 6.6 +|- 5.6 

All Systems

Employee Expenses 28.0 29.8 32.3 33.8 30.6 27.6 33.5 

Confidence interval +|- 7.7 +|- 6.6 +|- 4.1 +|- 3.4 +|- 3.2 +|- 2.2 +|- 10.4 

Routine Operating Expenses 70.5 62.1 52.3 47.6 44.8 47.1 39.8 

Confidence interval +|- 8.0 +|- 6.8 +|- 4.2 +|- 4.5 +|- 4.7 +|- 3.7 +|- 5.8 

Debt Service Expenses: 2.1 5.8 11.8 14.3 19.2 19.8 16.3 

Confidence interval +|- 2.2 +|- 2.0 +|- 2.8 +|- 4.0 +|- 4.8 +|- 3.3 +|- 3.6 

Other Expenses: 1.3 2.8 3.7 5.0 6.1 5.6 10.6 

Confidence interval +|- 1.4 +|- 2.4 +|- 2.7 +|- 2.6 +|- 2.4 +|- 2.4 +|- 4.7 

Data: Q.31Notes: Column totals may not sum to 100 due to rounding.

Employee expenses includes contract employees.

94 
Table 63

Total Expenses

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Mean 4.16 2.53 2.97 1.95 2.01 1.70 2.02 

Confidence interval +|- 1.93 +|- 0.50 +|- 0.59 +|- 0.42 +|- 0.30 +|- 0.23 +|- 0.30 

Median 2.24 1.91 2.41 1.59 1.90 1.67 1.95 Observations 72 79 86 60 43 26 36 

Primarily Surface Water Systems

Mean 2.72 3.84 4.19 3.22 2.01 1.67 1.55 

Confidence interval +|- 1.06 +|- 1.14 +|- 1.32 +|- 0.88 +|- 0.25 +|- 0.23 +|- 0.10 

Median 8.15 3.72 2.95 2.34 1.90 1.54 1.41 Observations 30 44 66 69 72 51 103 

Primarily Purchased Water Systems

Mean 2.49 4.48 5.05 2.52 3.90 2.63 2.02 

Confidence interval +|- 0.13 +|- 1.17 +|- 1.15 +|- 0.35 +|- 1.42 +|- 0.51 +|- 0.23 

Median 2.47 3.37 4.24 2.38 3.24 2.52 2.08 Observations 6 20 47 22 24 24 43 

All Systems

Mean 4.08 2.90 3.63 2.32 2.43 1.91 1.82 

Confidence interval +|- 1.84 +|- 0.46 +|- 0.54 +|- 0.34 +|- 0.46 +|- 0.20 +|- 0.16 

Median 2.25 2.25 2.90 2.00 2.11 1.67 1.93 Observations 108 143 199 151 139 101 182 

Data: Q.31Notes: Two surface water systems serving 25-100 people with expenses greater than $20 per thousan

produced were dropped from the estimate. If included, the mean expenses are $12.59.

(Dollars per Thousand Gallons Produced)

95 
Table 64

Total Expenses

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean 3.83 3.53 3.35 2.22 2.44 1.88 1.80 

Confidence interval +|- 1.86 +|- 0.86 +|- 0.61 +|- 0.37 +|- 0.51 +|- 0.21 +|- 0.17 

Median 2.86 3.19 2.76 1.97 2.05 1.67 1.93 Observations 13 66 171 133 124 93 169 

Private Systems

Mean 4.10 2.50 4.98 2.92 2.31 2.27 2.08 

Confidence interval +|- 1.94 +|- 0.51 +|- 1.23 +|- 0.69 +|- 0.67 +|- 0.54 +|- 0.35 

Median 2.24 2.00 3.25 2.72 2.30 2.11 2.09 Observations 95 77 28 18 15 8 13 

All Systems

Mean 4.08 2.90 3.63 2.32 2.43 1.91 1.82 

Confidence interval +|- 1.84 +|- 0.46 +|- 0.54 +|- 0.34 +|- 0.46 +|- 0.20 +|- 0.16 

Median 2.24 2.25 2.90 2.00 2.11 1.67 1.93 Observations 108 143 199 151 139 101 182 

Data: Q.7, Q.31Notes: Two private systems serving 25-100 people with expenses greater than $20 per thousand gallo

produced were dropped from the estimate. If included, the mean expenses are $4.84 per thou

(Dollars per Thousand Gallons Produced)

96 
Table 65

Ratio of Total Revenue to Total Expenses

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Over 

500,000 Al

Public Systems

Average Ratio 2.1 1.1 1.3 1.2 1.1 1.3 1.2 1.2 

Confidence interval +|- 1.0 +|- 0.2 +|- 0.2 +|- 0.1 +|- 0.0 +|- 0.2 +|- 0.0 +|- 0.0 

10th Percentile 0.8 0.6 0.8 0.9 0.8 0.9 0.9 0.9 25th Percentile 1.2 0.9 0.9 1.0 1.0 1.0 1.0 1.0 50th Percentile 1.7 1.1 1.1 1.1 1.1 1.1 1.1 1.1 75th Percentile 3.4 1.4 1.4 1.3 1.2 1.2 1.3 1.2 90th Percentile 3.4 1.6 2.3 1.7 1.4 1.6 1.5 1.6 Observations 11 64 169 132 124 91 169 47 

Private Systems

Average Ratio 1.5 1.5 1.1 1.3 1.2 1.3 1.2 1.2 

Confidence interval +|- 0.3 +|- 0.3 +|- 0.1 +|- 0.3 +|- 0.2 +|- 0.2 +|- 0.2 +|- 0.1 

10th Percentile 0.5 0.8 0.9 0.8 1.0 1.0 1.0 1.1 25th Percentile 1.0 0.8 1.0 1.1 1.0 1.1 1.0 1.1 50th Percentile 1.2 1.1 1.1 1.2 1.2 1.2 1.1 1.2 75th Percentile 1.8 1.8 1.2 1.3 1.3 1.4 1.2 1.4 90th Percentile 2.8 2.5 1.3 2.2 1.6 2.1 1.8 1.4 Observations 66 43 26 16 14 9 13 3 

All Systems

Average Ratio 1.5 1.3 1.3 1.2 1.1 1.3 1.2 1.2 

Confidence interval +|- 0.3 +|- 0.1 +|- 0.1 +|- 0.1 +|- 0.0 +|- 0.1 +|- 0.0 +|- 0.0 

10th Percentile 0.5 0.7 0.8 0.9 0.8 0.9 0.9 0.9 25th Percentile 1.0 0.9 1.0 1.0 1.0 1.0 1.0 1.0 50th Percentile 1.2 1.1 1.1 1.1 1.1 1.1 1.1 1.1 75th Percentile 1.8 1.5 1.3 1.3 1.2 1.2 1.3 1.2 90th Percentile 3.0 2.0 2.0 1.8 1.4 1.6 1.6 1.6 Observations 77 107 195 148 138 100 182 50 

Data: Q.26C, Q.31ENotes: Refer to next table for additional detail on private systems.

One public system in Colorado serving less than 100 people with a large ratio of revenue to expenses o4.54 was dropped. If included the ratio for public systems serving less than 100 people is 2.5. One private system serving 25-100 with a revenue to expense ratio of 15 was dropped. If included, theaverage ratio is 1.8.

97 
Table 66

Ratio of Total Revenue to Total Expenses

By Type

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300 All Sizes

Private Systems

Average Ratio 1.5 1.5 1.1 1.4

Confidence interval +|- 0.4 +|- 0.3 +|- 0.1 +|- 0.2

10th Percentile 0.5 0.8 0.9 0.625th Percentile 0.9 0.8 1.0 0.950th Percentile 1.2 1.1 1.1 1.175th Percentile 2.0 1.8 1.2 1.690th Percentile 3.0 2.5 1.3 2.5Observations 62 41 25 128

Ancillary Systems

Average Ratio 1.3 0.6 0.6 1.2

Confidence interval +|- 0.4 +|- 0.1 +|- 0.0 +|- 0.3

10th Percentile 1.0 0.6 0.6 0.725th Percentile 1.0 0.6 0.6 1.050th Percentile 1.4 0.6 0.6 1.075th Percentile 1.8 0.7 0.6 1.890th Percentile 15.0 0.7 0.6 15.0Observations 4217

All Private Systems

Average Ratio 1.5 1.5 1.1 1.4

Confidence interval +|- 0.3 +|- 0.3 +|- 0.1 +|- 0.2

10th Percentile 0.5 0.8 0.9 0.625th Percentile 1.0 0.8 1.0 0.950th Percentile 1.2 1.1 1.1 1.175th Percentile 1.8 1.8 1.2 1.790th Percentile 3.0 2.5 1.3 2.5Observations 66 43 26 135

Data: Q.7, Q.26, Q.31Notes: One ancillary system serving 25-100 with a revenue to

expense ratio of 15 has been dropped from the meanestimate but included in the median. If included in themean, the mean ratio is 3.7.

98 
Table 67

Number of Employees and Annual Labor Costs

By Primary Source of Water

(Labor Costs in Thousands of Dollars)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

5

Primarily Ground Water Systems

Mean Number of Employees 1.3 1.6 2.8 5.7 15.2 42.1 64.6 

Confidence interval +|- 0.3 +|- 0.4 +|- 0.6 +|- 1.1 +|- 2.6 +|- 13.7 +|- 34.7 +|- 

Mean Annual Labor Costs 5 12 38 190 636 1,755 2,616 

Confidence interval +|- 3 +|- 4 +|- 9 +|- 40 +|- 137 +|- 231 +|- 1,495 +|- 

Primarily Surface Water Systems

Mean Number of Employees 1.2 8.3 3.6 8.2 23.8 45.6 117.6 

Confidence interval +|- 0.3 +|- 9.0 +|- 0.8 +|- 1.5 +|- 8.3 +|- 8.4 +|- 11.2 +|- 

Mean Annual Labor Costs 6 25 117 270 798 1,865 5,312 

Confidence interval +|- 6 +|- 9 +|- 28 +|- 39 +|- 114 +|- 415 +|- 507 +|- 

Primarily Purchased Water Systems

Mean Number of Employees * 1.4 2.7 6.7 25.4 35.3 75.0 

Confidence interval * +|- 0.4 +|- 0.5 +|- 1.4 +|- 19.4 +|- 8.6 +|- 11.2 +|- 

Mean Annual Labor Costs * 4 39 188 618 1,853 3,714 

Confidence interval * +|- 3 +|- 10 +|- 50 +|- 265 +|- 436 +|- 576 +|- 

All Systems

Mean Number of Employees 1.3 2.5 2.9 6.4 20.4 42.0 88.3 

Confidence interval +|- 0.3 +|- 1.5 +|- 0.4 +|- 0.8 +|- 5.3 +|- 5.9 +|- 18.4 +

Mean Annual Labor Costs 5 12 46 206 686 1,829 3,983 

Confidence interval +|- 2 +|- 3 +|- 8 +|- 28 +|- 95 +|- 223 +|- 854 +|- 

Data: Q.31ANotes: *No data collected for purchased water systems with a population of less than 100 people.

Labor costs includes wages, salaries, fringe benefits, and contractors.Two ground water sytems serving 25-100 people were dropped from the calculations becausoutliers. This had little effect on the calculations.

99 
Table 68

Number of Employees and Annual Labor Costs

By Ownership

(Labor Costs in Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean Number of Employees 1.6 1.6 2.8 6.4 21.7 43.1 89.5 

Confidence interval +|- 0.7 +|- 0.3 +|- 0.4 +|- 0.9 +|- 6.2 +|- 6.5 +|- 19.8 

Annual Labor Costs 13 12 46 201 703 1,843 3,922 

Confidence interval +|- 5 +|- 5 +|- 8 +|- 27 +|- 104 +|- 242 +|- 896 +

Private Systems

Mean Number of Employees 1.3 3.5 3.3 6.7 12.6 31.8 72.4 

Confidence interval +|- 0.3 +|- 3.2 +|- 1.4 +|- 1.7 +|- 3.5 +|- 6.7 +|- 25.3 

Annual Labor Costs 5 12 44 244 568 1,677 4,864 

Confidence interval +|- 2 +|- 5 +|- 17 +|- 112 +|- 228 +|- 369 +|- 1,743 +|- 

All Systems

Mean Number of Employees 1.3 2.5 2.9 6.4 20.4 42.0 88.3 

Confidence interval +|- 0.3 +|- 1.5 +|- 0.4 +|- 0.8 +|- 5.3 +|- 5.9 +|- 18.4 

Annual Labor Costs 5 12 46 206 686 1,829 3,983 

Confidence interval +|- 2 +|- 3 +|- 8 +|- 28 +|- 95 +|- 223 +|- 854 +

Data: Q.31Notes: Labor costs includes wages, salaries, fringe benefits, and contractors.

Two public systems serving 25-100 people were dropped from the calculations do to high labor cmean number of employees are 2.0 and annual labor costs are $37,000 for this category.

100 
Table 69

Percentage of Systems Making Major Capital Improvements in the Past 5 Years

By Primary Source of Water

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Percentage of Systems 43.2 49.9 51.4 69.6 80.3 89.6 73.6 

Confidence interval +|- 12.0 +|- 12.4 +|- 11.7 +|- 11.8 +|- 10.8 +|- 9.4 +|- 24.2 

 Observations 104 93 92 67 50 29 44 Primarily Surface Water Systems

Percentage of Systems 21.0 74.5 77.9 76.4 87.0 79.7 91.3 

Confidence interval +|- 16.6 +|- 20.6 +|- 12.2 +|- 9.4 +|- 7.0 +|- 13.8 +|- 3.2 

 Observations 46 55 69 76 83 58 110 Primarily Purchased Water Systems

Percentage of Systems 15.8 57.8 47.9 57.3 86.4 86.8 83.2 

Confidence interval +|- 27.1 +|- 26.2 +|- 18.4 +|- 18.4 +|- 13.2 +|- 10.7 +|- 8.8 

 Observations 6 23 50 27 28 30 48 All Systems

Percentage of Systems 41.6 52.7 52.8 68.6 83.9 84.4 82.9 

Confidence interval +|- 11.2 +|- 10.5 +|- 8.6 +|- 8.3 +|- 6.1 +|- 7.6 +|- 9.4 

 Observations 156 171 211 170 161 117 202 Data: Q.32A7

101 
Table 70

Percentage of Systems Making Major Capital Improvements in the Past 5 Years

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

5

Public Systems

Mean 65.1 58.7 52.0 69.1 84.3 84.8 83.7 

Confidence interval +|- 35.4 +|- 15.0 +|- 9.0 +|- 9.2 +|- 6.7 +|- 8.3 +|- 10.2 

Observations 18 76 179 148 138 101 183 

Private Systems

Mean 49.4 55.9 65.4 81.7 81.5 74.3 51.0 

Confidence interval +|- 13.7 +|- 21.0 +|- 22.1 +|- 14.6 +|- 16.8 +|- 15.6 +|- 23.2 +

Observations 95 32 22 23 16 19 6 

All Systems

Mean 52.8 68.6 83.9 84.4 82.9 88.6 61.2 

Confidence interval +|- 8.6 +|- 8.3 +|- 6.1 +|- 7.6 +|- 9.4 +|- 4.6 +|- 5.7 

Observations 211 170 161 117 202 58 895 

Data: Q.32A

102 
Table 71

Total Capital Investment in the Past 5 Years

By Primary Source of Water

(Thousands of Dollars)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Mean 35 97 309 923 3,392 7,001 17,656 

Confidence interval +|- 17 +|- 59 +|- 93 +|- 287 +|- 1,056 +|- 1,393 +|- 12,506 +

Median 9 21 156 550 2,700 6,782 4,896 Observations 49 51 49 46 38 23 35 

Primarily Surface Water Systems

Mean 111 387 892 1,763 3,514 14,277 33,868 

Confidence interval +|- 91 +|- 280 +|- 393 +|- 774 +|- 878 +|- 3,844 +|- 3,824 +

Median 17 140 370 919 2,194 8,675 24,986 Observations 23 38 50 55 71 49 99 

Primarily Purchased Water Systems

Mean 16 229 346 962 8,743 13,410 20,656 

Confidence interval +|- 12 +|- 290 +|- 184 +|- 677 +|- 6,855 +|- 5,771 +|- 4,696 +

Median 23 12 100 325 2,127 6,466 15,077 Observations 2 12 27 16 23 25 39 

All Systems

Mean 38 144 392 1,119 4,648 11,895 25,649 

Confidence interval +|- 17 +|- 68 +|- 91 +|- 275 +|- 1,861 +|- 2,398 +|- 6,062 +

Median 9 23 189 512 2,232 7,468 17,069 Observations 74 101 126 117 132 97 173 

Data: Q.32A

103 
Table 72

Total Capital Investment in the Past 5 Years

By Ownership

(Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Public Systems

Mean 204 291 385 1,128 4,940 11,591 24,732 

Confidence interval +|- 128 +|- 164 +|- 94 +|- 302 +|- 2,165 +|- 2,581 +|- 6,360 +

Median 110 105 189 512 2,232 6,778 15,954 Observations 11 44 109 102 115 85 159 

Private Systems

Mean 21 49 418 1,056 3,053 14,446 36,474 

Confidence interval +|- 11 +|- 26 +|- 239 +|- 639 +|- 1,388 +|- 6,360 +|- 10,478 +

Median 8 14 373 500 2,700 9,620 27,422 Observations 63 57 17 15 17 12 14 

All Systems

Mean 38 144 392 1,119 4,648 11,895 25,649 

Confidence interval +|- 17 +|- 68 +|- 91 +|- 275 +|- 1,861 +|- 2,398 +|- 6,062 +

Median 9 23 189 512 2,232 7,468 17,069 Observations 74 101 126 117 132 97 173 

Data: Q.32A

104 
Table 73

Type of Capital Expenses in the Past 5 Years

By Primary Source of Water

(Percentage of Systems Reporting Each Type of Expense)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Land 1.1 2.5 5.0 26.5 27.7 13.6 28.9 Water Source 30.6 48.7 31.0 49.6 47.8 64.6 47.6 Distribution and Transmission System 40.7 61.7 73.2 70.6 84.9 96.4 100.0 Treatment 27.6 32.3 34.0 39.5 59.7 61.9 42.0 Storage 30.4 35.1 40.0 43.1 47.9 60.1 80.2 Other 11.9 19.8 17.5 28.7 41.7 65.6 45.9 Observations 49 51 49 46 38 23 35 

Primarily Surface Water Systems

Land 0.0 3.6 3.8 21.4 18.8 24.0 38.7 Water Source 25.2 12.3 22.7 30.2 21.8 42.5 52.8 Distribution and Transmission System 39.7 53.2 62.2 82.3 82.7 98.1 89.0 Treatment 55.0 71.5 38.5 63.7 65.4 90.3 89.1 Storage 25.1 38.7 28.5 33.3 48.6 52.9 64.8 Other 23.7 13.2 9.8 27.3 40.6 49.0 63.8 Observations 23 38 50 55 71 49 99 

Primarily Purchased Water Systems

Land 0.0 0.0 0.0 27.4 36.3 26.7 33.3 Water Source 0.0 0.0 5.8 4.3 8.6 30.3 39.6 Distribution and Transmission System 0.0 71.2 84.3 68.8 100.0 85.1 97.8 Treatment 0.0 0.8 1.2 4.3 22.2 17.2 41.5 Storage 100.0 39.9 20.9 54.9 42.4 27.5 65.6 Other 0.0 1.1 2.9 27.4 12.2 43.4 57.0 Observations 2 12 27 16 23 25 39 

All Systems

Land 1.1 2.3 3.6 25.5 26.6 21.6 34.1 Water Source 30.4 38.7 23.5 37.9 30.4 46.0 48.1 Distribution and Transmission System 40.5 62.1 74.6 73.0 87.6 94.1 94.7 Treatment 28.4 32.2 26.2 39.4 53.4 61.9 62.5 Storage 30.3 36.1 33.7 42.8 46.9 48.3 70.2 Other 12.3 16.7 12.8 28.2 34.8 52.6 56.2 Observations 74 101 126 117 132 97 173 

Data: Q.32A

105 
Table 74

Type of Capital Expenses in the Past 5 Years

By Primary Source of Water

(Thousands of Dollars)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Primarily Ground Water Systems

Land 1 277 350 102 147 282 841 Water Source 8 11 71 307 823 2,475 4,337 Distribution and Transmission System 41 97 176 490 1,772 3,285 6,488 Treatment 29 57 191 401 1,261 1,301 12,276 Storage 26 17 162 431 979 795 1,897 Other 3 7 54 278 560 1,392 4,360 Observations 49 51 49 46 38 23 35 

Primarily Surface Water Systems

Land 0 35 39 164 117 139 1,185 Water Source 2 17 285 442 1,194 1,254 9,778 Distribution and Transmission System 174 155 610 842 2,057 5,347 14,339 Treatment 63 327 943 1,169 1,189 7,604 12,595 Storage 12 111 253 411 773 1,677 2,998 Other 11 34 282 153 515 1,847 5,086 Observations 23 38 50 55 71 49 99 

Primarily Purchased Water Systems

Land 0 0 0 65 452 4,871 1,399 Water Source 0 0 49 3,863 343 10,699 6,389 Distribution and Transmission System 0 107 303 605 7,681 5,938 10,247 Treatment 0 18 30 3,367 619 7,264 9,612 Storage 16 78 420 376 1,713 2,599 3,905 Other 0 6 82 128 482 4,993 2,671 Observations 2 12 27 16 23 25 39 

All Systems

Land 1 239 309 108 232 1,746 1,130 Water Source 8 11 96 396 883 3,456 7,320 Distribution and Transmission System 45 104 258 599 3,407 4,846 10,566 Treatment 31 117 329 739 1,172 5,652 12,092 Storage 26 36 213 416 1,055 1,483 2,747 Other 4 9 78 227 536 2,374 4,350 Observations 74 101 126 117 132 97 173 

Data: Q.32A

106 
Table 75

Type of Capital Expenses in the Past 5 Years

By Primary Source of Water

(Percentage of Funds Allocated for Each Type of Expense)

System Service Population Category

Primary Source of Water

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Primarily Ground Water Systems

Land 0.0 7.1 5.7 2.9 1.2 0.5 1.4 Water Source 7.3 5.5 7.2 16.0 11.6 22.8 11.8 Distribution and Transmission System 46.9 61.2 41.8 36.3 44.3 45.2 37.1 Treatment 22.4 18.7 21.1 16.6 22.2 11.5 29.5 Storage 22.2 6.1 21.1 19.9 13.8 6.8 8.7 Other 1.2 1.4 3.1 8.4 6.9 13.0 11.5 Observations 49 51 49 46 38 23 35 

Primarily Surface Water Systems

Land 0.0 0.3 0.2 2.0 0.7 0.2 1.3 Water Source 0.4 0.6 7.1 7.5 7.8 3.7 14.8 Distribution and Transmission System 62.9 22.5 41.8 38.8 50.9 36.2 36.7 Treatment 31.6 63.7 40.0 41.7 23.3 47.4 32.3 Storage 2.7 11.7 7.9 7.7 11.1 6.1 5.5 Other 2.4 1.2 3.1 2.3 6.3 6.3 9.3 Observations 23 38 50 55 71 49 99 

Primarily Purchased Water Systems

Land 0.0 0.0 0.0 1.8 1.8 9.5 2.2 Water Source 0.0 0.0 0.8 16.8 0.3 23.6 12.0 Distribution and Transmission System 0.0 70.9 73.2 42.3 87.8 36.8 47.5 Treatment 0.0 0.1 0.1 14.6 1.5 9.1 18.9 Storage 100.0 28.9 25.2 20.9 7.9 5.2 12.1 Other 0.0 0.1 0.7 3.6 0.6 15.8 7.2 Observations 2 12 27 16 23 25 39 

All Systems

Land 0.0 4.4 2.8 2.4 1.3 3.1 1.5 Water Source 6.6 3.4 5.7 13.1 5.8 13.3 13.6 Distribution and Transmission System 48.4 50.9 48.9 38.0 64.9 38.0 38.7 Treatment 23.2 29.9 21.9 25.3 13.4 29.2 29.3 Storage 20.5 10.3 18.2 15.7 10.6 6.0 7.4 Other 1.3 1.2 2.5 5.5 4.0 10.4 9.5 Observations 74 101 126 117 132 97 173 

Data: Q.32ANotes: Column totals may not sum to 100 due to rounding.

107 
Table 76

Major Capital Expense Categories in the Past 5 Years

By Ownership

(Percentage of Systems Investing Capital Funds in Each Category)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Public Systems

Water Quality Improvements 91.9 26.9 18.1 38.5 58.3 54.7 79.1 Replacement or Major Repair 33.4 74.9 65.6 87.5 77.9 87.9 78.3 System Expansion 1.8 23.6 49.0 65.4 64.4 74.7 83.9 Observations 11 42 106 90 109 82 139 

Private Systems

Water Quality Improvements 29.7 50.1 63.2 77.6 54.6 81.1 87.1 Replacement or Major Repair 74.5 75.7 53.9 65.4 71.8 100.0 94.1 System Expansion 17.6 22.2 76.9 89.9 86.8 81.1 87.1 Observations 61 53 17 13 17 11 13 

All Systems

Water Quality Improvements 35.6 40.6 27.9 43.3 57.7 57.4 79.8 Replacement or Major Repair 70.7 75.4 63.1 84.7 76.9 89.2 79.6 System Expansion 16.1 22.8 55.1 68.4 68.1 75.4 84.2 Observations 72 95 123 103 126 93 152 

Data: Q.32A, Q.32BNotes: Includes systems with positive capital expenses only.

108 
Table 77

Major Capital Expense Categories in the Past 5 Years

By Ownership

(Capital Funds Invested Per System in Each Category, in Thousands of Dollars)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000 Over 500,000 

Public Systems

Water Quality Improvements 90 84 72 340 774 1,768 3,816 43,573 Replacement or Major Repair 87 124 178 506 1,231 4,753 8,759 92,941 System Expansion 27 81 141 293 3,041 5,364 11,851 128,082 Observations 11 42 106 90 109 82 139 41 

Private Systems

Water Quality Improvements 2 8 44 345 600 5,088 8,837 15,659 Replacement or Major Repair 7 20 86 340 985 6,852 17,517 40,396 System Expansion 12 22 287 477 1,469 2,897 10,630 81,105 Observations 61 53 17 13 17 11 13 3 

All Systems

Water Quality Improvements 10 39 66 340 746 2,109 4,226 41,732 Replacement or Major Repair 15 62 158 486 1,191 4,969 9,473 89,475 System Expansion 13 46 172 315 2,786 5,111 11,751 124,983 Observations 72 95 123 103 126 93 152 44 

Data: Q.32A, Q.32BNotes: Includes systems with positive capital expenses only.

109 
Table 78

Major Capital Expense Categories in the Past 5 Years

By Ownership

(Percentage of Capital Funds Invested in Each Category)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

50

Public Systems

Water Quality Improvements 44.0 29.2 18.4 29.8 15.3 14.9 15.6 Replacement or Major Repair 42.8 42.9 45.6 44.5 24.4 40.0 35.9 System Expansion 13.2 28.0 36.0 25.7 60.3 45.1 48.5 Observations 11 42 106 90 109 82 139 

Private Systems

Water Quality Improvements 7.8 16.2 10.5 29.7 19.7 34.3 23.9 Replacement or Major Repair 35.4 39.8 20.6 29.3 32.3 46.2 47.4 System Expansion 56.8 44.0 68.9 41.0 48.1 19.5 28.7 Observations 61 53 17 13 17 11 13 

All Systems

Water Quality Improvements 26.0 26.6 16.6 29.7 15.8 17.3 16.6 Replacement or Major Repair 39.1 42.3 39.9 42.6 25.2 40.8 37.2 System Expansion 34.8 31.1 43.5 27.7 59.0 41.9 46.2 Observations 72 95 123 103 126 93 152 

Data: Q.32A, Q.32BNotes: Column totals may not sum to 100 due to rounding.

Table reports the percentage of funds invested in each category in the nation and the aggre

percentage of funds invested on average by each system.

110 
Table 79

Source of Capital Funds in the Past 5 Years

By Ownership

(Percentage of Systems Making Capital Expenditures)

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Over 

500,000 

Public Systems

Current Revenues 6.3 63.8 70.1 73.9 79.9 81.7 90.4 95.9 DWSRF Loans 24.4 9.4 12.6 3.4 7.7 8.8 9.3 25.7 DWSRF Principal Repayment Forgiveness 16.3 14.0 6.9 1.5 4.3 3.5 2.9 2.1 Other Government Loans 0.0 13.1 12.6 14.2 16.4 8.3 7.4 2.1 Other Government Grants 6.5 28.3 17.9 28.0 21.6 13.8 6.0 6.2 Borrowing from Private Sector 3.2 10.0 12.6 27.3 36.0 50.5 40.8 75.1 Other 46.9 0.0 3.0 3.5 1.1 2.7 3.6 2.0 Observations 11 43 111 94 113 85 157 45 

Private Systems

Current Revenues 79.2 86.5 71.6 67.5 85.9 73.6 92.9 64.0 DWSRF Loans 0.0 0.0 0.0 0.0 3.2 0.0 14.1 36.0 DWSRF Principal Repayment Forgiveness 0.1 0.0 0.0 11.6 0.0 0.0 0.0 0.0 Other Government Loans 3.3 0.3 8.6 2.4 22.6 17.6 15.3 0.0 Other Government Grants 0.0 4.9 14.8 11.6 18.3 8.8 0.0 0.0 Borrowing from Private Sector 12.4 6.1 24.1 51.1 36.6 55.8 70.6 68.0 Other 7.5 3.9 6.9 9.3 10.4 0.0 0.0 0.0 Observations 64 59 16 14 15 10 12 3 

All Systems

Current Revenues 72.6 77.6 70.4 73.0 80.8 81.0 90.5 93.9 DWSRF Loans 2.2 3.5 10.0 2.9 7.0 8.0 9.6 26.3 DWSRF Principal Repayment Forgiveness 1.6 5.3 5.5 2.9 3.6 3.2 2.7 1.9 Other Government Loans 3.0 5.2 11.8 12.6 17.3 9.1 7.9 1.9 Other Government Grants 0.6 14.2 17.3 25.7 21.1 13.3 5.6 5.8 Borrowing from Private Sector 11.5 7.6 15.0 30.6 36.1 51.0 42.7 74.7 Other 11.0 2.4 3.8 4.3 2.6 2.4 3.4 1.9 Observations 75 102 127 108 128 95 169 48 

Data: Q.32CNotes: Systems can receive funds by more than one source; therefore column totals may not sum to 100

This table reports sources of capital funds only for those systems making capital expenditures in tThe DWSRF program may forgive all or a portion of the loan principal repayment by disadvantagequestionnaire refers to principal payment forgiveness as grants. This was done to distinguish prinrepaid from principal whose repayment is forgiven.

111 
Table 80

Source of Capital Funds in the Past 5 Years 

Percentage Distribution of the Sources of Funds for Investment for the Average System

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Over 

500,000 

Public Systems

Current Revenues 6.1 50.3 52.8 50.1 56.8 50.8 67.3 52.6 DWSRF Loans 24.4 4.6 10.8 3.0 3.2 3.7 3.9 1.4 DWSRF Principal Repayment Forgiveness 16.3 9.3 4.2 0.1 1.3 1.3 0.6 0.0 Other Government Loans 0.0 4.7 8.2 11.4 10.0 4.6 1.9 1.4 Other Government Grants 4.7 22.7 10.8 15.6 5.1 1.9 1.2 0.7 Borrowing from Private Sector 2.1 9.9 10.9 17.1 23.3 35.9 23.6 45.0 Other 46.3 0.0 2.5 2.0 0.2 1.6 1.3 0.1 Observations 11 43 111 94 113 85 157 45 

Private Systems

Current Revenues 78.0 84.8 65.1 52.1 56.2 54.9 67.8 56.0 DWSRF Loans 0.0 0.0 0.0 0.0 3.0 0.0 0.6 4.3 DWSRF Principal Repayment Forgiveness 0.1 0.0 0.0 4.7 0.0 0.0 0.0 0.0 Other Government Loans 3.3 0.3 4.7 1.8 5.0 5.3 5.4 0.0 Other Government Grants 0.0 4.8 10.0 4.1 10.9 1.6 0.0 0.0 Borrowing from Private Sector 12.2 3.3 13.3 28.3 24.9 38.2 26.2 39.7 Other 6.3 3.9 6.9 9.3 3.1 0.0 0.0 0.0 Observations 64 59 16 14 15 10 12 3 

All Systems

Current Revenues 71.5 71.4 55.3 50.4 56.7 51.2 67.3 52.8 DWSRF Loans 2.2 1.7 8.6 2.6 3.1 3.3 3.7 1.5 DWSRF Principal Repayment Forgiveness 1.6 3.5 3.4 0.7 1.1 1.2 0.6 0.0 Other Government Loans 3.0 2.0 7.5 10.1 9.3 4.7 2.1 1.3 Other Government Grants 0.4 11.9 10.6 13.9 6.0 1.9 1.1 0.6 Borrowing from Private Sector 11.3 5.8 11.4 18.6 23.5 36.1 23.8 44.6 Other 9.9 2.4 3.4 3.0 0.7 1.4 1.2 0.1 Observations 75 102 127 108 128 95 169 48 

Data: Q.32CNotes: This table reports sources of capital funds only for those systems making capital expenditures in t

The DWSRF program may forgive all or a portion of the loan principal repayment by disadvantagequestionnaire refers to principal payment forgiveness as grants. This was done to distinguish prinrepaid from principal whose repayment is forgiven.This table shows how much of each (average) system's total capital expenditures came from eacis not the percentage of funds acquired from each funding source for the nation in the aggregate. table 81.

112 
Table 81

Source of Capital Funds in the Past 5 Years

Percentage Distribution of the Sources of Funds for Investment for the Nation

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

Over 

500,000 

Public Systems

Current Revenues 2.3 14.5 27.2 34.0 49.9 38.9 54.5 29.0 DWSRF Loans 38.5 12.4 23.4 4.4 3.0 5.6 3.8 1.2 DWSRF Principal Repayment Forgiveness 8.3 13.3 11.1 0.5 0.9 0.8 0.3 0.0 Other Government Loans 0.0 13.4 14.6 17.3 20.7 6.2 2.2 0.3 Other Government Grants 9.4 42.6 10.6 13.7 7.0 1.3 3.0 0.5 Borrowing from Private Sector 16.7 3.9 10.9 26.3 18.5 43.1 34.1 68.7 Other 24.9 0.0 2.2 3.8 0.0 4.1 2.0 0.1 Observations 11 43 111 94 113 85 157 45 

Private Systems

Current Revenues 64.1 51.8 62.8 35.6 30.7 21.5 62.5 31.3 DWSRF Loans 0.0 0.0 0.0 0.0 4.7 0.0 0.9 7.5 DWSRF Principal Repayment Forgiveness 0.8 0.0 0.0 0.1 0.0 0.0 0.0 0.0 Other Government Loans 2.9 0.7 8.2 2.2 6.3 8.6 5.6 0.0 Other Government Grants 0.0 12.0 14.9 11.7 10.1 2.2 0.0 0.0 Borrowing from Private Sector 20.2 7.7 12.1 46.5 46.3 67.7 31.0 61.1 Other 11.9 27.8 1.9 3.9 2.0 0.0 0.0 0.0 Observations 64 59 16 14 15 10 12 3 

All Systems

Current Revenues 33.5 21.5 33.5 34.2 48.1 37.2 55.3 29.1 DWSRF Loans 19.1 10.0 19.3 3.8 3.2 5.1 3.5 1.5 DWSRF Principal Repayment Forgiveness 4.5 10.8 9.1 0.5 0.8 0.7 0.3 0.0 Other Government Loans 1.5 11.0 13.5 15.4 19.3 6.4 2.5 0.3 Other Government Grants 4.6 36.8 11.4 13.5 7.3 1.4 2.7 0.5 Borrowing from Private Sector 18.5 4.6 11.1 28.8 21.2 45.5 33.8 68.4 Other 18.3 5.2 2.1 3.9 0.2 3.7 1.8 0.1 Observations 75 102 127 108 128 95 169 48 

Data: Q.32A, Q.32CNotes: This table reports sources of capital funds only for those systems making capital expenditures in t

The DWSRF program may forgive all or a portion of the loan principal repayment by disadvantagequestionnaire refers to principal payment forgiveness as grants. This was done to distinguish prinrepaid from principal whose repayment is forgiven.Of all capital expenditures spent nationally, this table reports how much that came from each fundnot report how much came from each source for each system on average. That is reported in tab

113 
Table 82

Average Interest Rate for Capital Funds Lending Sources

By Ownership

System Service Population Category

Ownership Type

100 

or Less

101 - 

500

501 - 

3,300

3,301 - 

10,000

10,001 - 

50,000

50,001 - 

100,000

100,001-

500,000

5

Public Systems

DWSRF Loans * 0.3 4.3 1.6 3.9 3.0 3.1 Other Government Loans * 1.2 2.0 3.5 3.4 4.2 3.8 Borrowing from Private Sector 6.0 6.8 4.6 4.8 4.3 5.1 5.4 Other * * 0.9 1.5 * * 5.5 Observations 1 8 32 30 42 41 71 

Private Systems

DWSRF Loans * * * * 2.5 * 1.9 Other Government Loans * 4.5 5.3 * 6.2 3.3 5.4 Borrowing from Private Sector 4.8 1.4 0.5 9.5 3.3 5.6 7.6 Other ***** * * Observations 2 7 3 1 6 5 5 

All Systems

DWSRF Loans * 0.3 4.3 1.6 3.8 3.0 3.0 Other Government Loans * 1.3 2.6 3.5 3.9 3.9 3.9 Borrowing from Private Sector 4.8 3.8 3.2 5.0 4.2 5.2 5.6 Other * * 0.9 1.5 * * 5.5 Observations 3 15 35 31 48 46 76 

Data: Q.32CNotes: *No data available for these systems

This table reports systems making capital expenditures in the past 5 years and reporting thrates.

114 
115

Part 2

Methodology Report
116
117

1. INTRODUCTION

1.1 Study Background

In compliance with Executive Order 12866, the Regulatory Flexibility Act, and the Safe

Drinking Water Act (SDWA), the U.S. Environmental Protection Agency’s Office of Ground Water

and Drinking Water (OGWDW), Standards and Risk Management Division (SRMD) conducts

periodic surveys of the financial and operating characteristics of community water systems. These

Community Water System Suveys (CWSSs) supply information that is essential to support economic

analyses of the costs and benefits of new regulations and changes to existing regulations on consumers,

the water supply industry, and the nation. The information also will be used to measure the financial

burden of EPA’s regulations on consumers and the industry. Furthermore, data from the survey will

help EPA identify, evaluate and develop guidance on Best Management Practices used in water

treatment and distribution systems. Previous surveys of Community Water Systems were conducted in

1976, 1982, 1986, and 1995. 

1.2 Survey Overview

This section is intended to provide the reader with an overview of the design and conduct of the

CWSS. The topics presented in this section will then be discussed at greater length in the following

chapters. 

The CWSS was designed to collect operating and financial information from a representative

sample of community water systems. In order to reduce the burden of the survey on small systems, the

data were collected from systems serving 3,300 or fewer people through site visits by water system

professionals. Systems serving over 3,300 people received the questionnaire in the mail. Water system

professionals were assigned to each system that received the mailed questionnaire to help the systems

respond to the survey’s questions. A toll-free telephone number and an e-mail address also were

provided to the systems to provide technical support. 

The Community Water System survey was based on a nationally representative sample of

community water systems. The sample was drawn from a list of approximately 53,000 systems in the

Safe Drinking Water Information System (SDWIS). The survey used a stratified random sample

design to ensure the sample is representative. The sample was stratified by several characteristics of

water systems to increase the efficiency of estimates based on the sample. To limit the travel costs

involved in visiting each small system in the sample, they were selected in geographic clusters in a twostage design. A sample of 1,806 systems was selected, including a census of all systems serving

populations of 100,000 or more. 
118

A separate version of the questionnaire was developed for systems serving more than 500,000

people. Additional questions were asked of these very large systems regarding concentrations of 

several contaminants in raw and finished water and average well depth. Questions that would not apply

to very large systems were excluded from their version of the questionnaire. 

Water system professionals contacted the small systems in the sample to schedule appointments

for the site visits. Upon mailout, each system receiving the questionnaire was notified by telephone that

they would receive the questionnaire in the mail. Phone calls were made throughout the data collection

period to encourage non-respondents to participate and to provide technical support when needed. 

Requests to re-mail the questionnaire were received through the toll-free support line and during the

phone calls to the system; the questionnaires were re-mailed as the requests were received. 

As completed questionnaires were returned, they were logged into a receipt control system

using an on-line data tracking system. The completed questionnaires went through an extensive data

quality review. Water system analysts reviewed each mailout questionnaire and contacted the systems

to clarify answers, correct anomalous items, or collect missing responses. The questionnaires were then

reviewed by senior engineering staff. The senior staff also reviewed the site visits reports for each small

system. The questionnaires were then key-entered using independent double-key entry. Finally, the

electronic form of the data were run through automated cleaning and editing programs. 

A series of sample weights, non-response adjustments, and other statistical techniques were

created and applied to the final set of sampled respondents. These weights allow for extrapolation from

the sampled systems to the universe of Community Water Systems in the nation. The sample design

and weights also allow for the calculation of confidence intervals for each estimate. 

Planning and design of the survey began in August of 1999. A pre-test of the questionnaire was

conducted in July 2000. The pilot test was conducted from April to May, 2001, and the final design

was developed in May 2001. Data collection took place from June through October, 2001. Data

processing and analysis continued through February 2002. 

EPA secured the services of several contractors who performed a variety of tasks in support of

the survey design, survey administration, data processing, and analysis. The Cadmus Group, Inc., was

the prime contractor. Abt Associates, Inc. served as a subcontractor, as did Norfolk Data, Inc. The

site visits were conducted through subcontracts with several experienced water system professionals. 

The Cadmus Group has been supporting EPA and other clients in the assessment and analysis of the

water industry for over 20 years. Cadmus’ primary responsibilities were for overall project

management; design of the questionnaire; sample design; selection of the medium, large, and very large

system sample; design, administration, and management of the data collection; technical support to

water systems in the sample; expert quality assurance review of the survey data; data tabulations; and

report preparation. Abt Associates assisted with the development of the survey instrument, selected

the small system sample, developed and maintained the on-line data tracking system, edited and
119

prepared the data into final form for data entry, managed the data entry, calculated the sample weights,

assisted in the data tabulations, and developed the final data with documentation. Norfolk Data keyed

the data into the electronic data base. 

EPA also requested comments on the survey from several independent reviewers. EPA

consulted with Jeanne Bailey in the office of Regulatory Affairs at the American Water Works

Association in Washington, DC. Drafts of the questionnaire were reviewed by Diane Moles, from the

Iowa Department of Natural Resources, in Des Moines, IA, and James K. Cleland of the Drinking

Water and Radiological Protection Division of the Michigan DEQ in Lansing, MI. EPA also consulted

with Robert W. Mann of the Water Supply Engineering Bureau of the State of New Hampshire's

Department of Environmental Services. 
120

2. SAMPLE DESIGN AND WEIGHTING

2.1 Sample Design and Selection

This section describes the sample design for the 2000 Community Water System Survey

(CWSS). It includes a description of the sampling frame, target sample size, stratification variables, and

sampling methods. 

The survey relied on a probability sample of Community Water Systems. For small systems

(those serving populations of 3,300 or less), a two-stage cluster sample was used. A stratified random

sample was used for systems serving populations of between 3,301 and 100,000. Systems serving

populations of over 100,000 were selected with certainty. The strata were defined by the combinations

of the size of the residential population served by the water systems and the source of water (ground or

surface). 

2.1.1 SDWIS Sampling Frame and Coverage

The sampling frame is developed from the federal Safe Drinking Water Information System

(SDWIS/Fed). SDWIS is a centralized database of information on public water systems, including

their compliance with monitoring requirements, maximum contaminant levels (MCLs), and other

requirements of the Safe Drinking Water Act (SDWA) Amendments of 1996. The following

information was extracted from SDWIS for the statistical survey: 

C Name of system

C Address of system

C Population served

C Primary source (surface water or ground water)

C Public water system identification number (PWSID)

C Ownership type 

C Consecutive system (i.e., does system purchase or sell water)

From these data, EPA developed a sample list from which it (1) calculated summary statistics

for use in calculating sample size, and (2) randomly chose systems within the design strata which will

take part in the survey.
121

SDWIS is the appropriate sampling frame because:

C It fully covers the target population.

C It contains no duplication.

C It contains no foreign elements (i.e., elements that are not members of the population).

C It contains information for identifying and contacting the units selected in the sample.

C It contains other information that will improve the efficiency of the sample design.

SDWIS is the best choice for a sample frame because of its inclusive coverage of all units of

observation for this survey. In addition, SDWIS has two other advantages: it contains information that

will facilitate contacting the respondents, and it contains other information that is useful in stratifying the

sample, thereby improving the efficiency of the sample design. However, SDWIS is not designed to be

such a sample frame; many properties of SDWIS, and some lingering problems of system classification

in SDWIS, can result in many inaccuracies for such sample frame applications and sample selection. 

For EPA's 1999 Drinking Water Infrastructure Needs Survey (Needs Survey), EPA and

Cadmus made a considerable effort to improve the SDWIS information and create an inventory list

more suitable as a sample frame. The Needs Survey took several steps to prepare SDWIS for use as

a sample frame. Problematic data were first identified based on the experience of the 1995 Needs

Survey. EPA then provided the confirmed inventory data to the States (including the Virgin Islands and

Puerto Rico) for review and asked the States to provide any necessary changes. 

EPA also worked with the States to identify the total "consecutive" population served (including

the population of retail buyers) by many prominent large systems, to group systems into size and type

categories that more accurately reflect actual populations served by a particular water system. For

instance, the reported population served by the Metropolitan Water District of Southern California

(MWD) is categorized as a small system serving less than 3,300 people in SDWIS; in fact, MWD

serves nearly 16 million consumers. Therefore, the system was reclassified as a large system, which

accurately reflects the way this system is regulated under the Safe Drinking Water Act. 

Criteria used to determine the accuracy of SDWIS data include: (1) 1995 inventory

verification showing a discrepancy rate greater than 1 percent; or (2) the number of community water

systems in a State in SDWIS as of March 1998 being at least 3 percent greater than in the sampling

frame used for the 1995 Needs Survey. On site inventory verifications were also conducted for States

that contributed to at least 0.8 percent of total national need in the 1995 Needs Survey, and if EPA

determined that SDWIS inventory may not accurately reflect a State's inventory, based on experience

with the 1995 Needs Survey. Inventory verifications were conducted in Arizona, Arkansas, California,
122

Colorado, New York, North Carolina, Ohio, Oklahoma, and Tennessee. SDWIS-Fed inventory

information for Virginia was replaced with SDWIS/State inventory information, since SDWIS/Fed was

known to be an inaccurate source of current inventory. 

The process of State corrections included a variety of inventory review procedures and data

verification:

C A stratified random sample of systems was used to select systems within each State to

verify the inventory. (A two-staged cluster sampling approach was used to select

systems in New York, since data in this State are managed by numerous district

offices.) 

C Sanitary survey information, bacteriological results, or other chemical records in State

files and/or databases were reviewed on site to ensure that inventory data were

accurate. If inventory information was different between SDWIS and the State files

and/or database, a discrepancy was issued. Each State so identified was then given an

opportunity to provide monitoring results or other documentation of a system's

characteristics, and in some cases, a system's actual existence. Systems that were

inactive were removed from the Needs Survey sampling frame, while other systems

were re-categorized if necessary. 

C Based on results of the inventory verification, the total inventory for each State was

further refined. The inventory verification results were extrapolated to all systems in

each State to estimate the number of active systems in each size and type category. 

In addition to these changes, the inventory of systems serving Alaskan native populations in

SDWIS was replaced with data developed by EPA Region 10 and the State of Alaska. 

The Needs Survey sample frame was further refined during the course of the data collection

period. System status as of January 1, 1999 was used to determine inclusion and placement within the

sample frame. 

The sample frame used for the Needs Survey is based on the SDWIS from 1998; to account

for changes in SDWIS, we compared the SDWIS available from the first quarter of 2000 to the Needs

Survey list. New systems were verified and added. This revised list of systems will be used as the

sample frame for the CWSS.
123

2.1.2 Sample Design and Selection

Sample Eligibility

To be eligible for the CWSS, a water system must meet several criteria. First, it must meet the

CFR definition of a community water system; principally, a water system providing drinking water to 25

or more permanent residents or to 15 permanent connections. (See 40 CFR 141.2 for the complete

definition.) In addition, the CWSS excluded federal- and state-owned or operated systems; because

these are not affected by regulatory and economic forces in the same way as other systems. To the

extent possible, all ineligible systems were identified in SDWIS and removed from the frame; however,

many ineligible systems could not be identified and were therefore left in the frame. If systems were

clearly identified as ineligible during data collection (e.g., they are no longer an active water system, they

no longer meet the CFR definition of a Community Water System, or they are owned by the federal or

a state government), the data were excluded from analyses based on the sample. 

After it drew the initial sample, EPA decided to exclude systems in the trust territories. The

original sample included 64 systems in Puerto Rico, the U.S. Virgin Islands, and the Pacific territories. 

EPA decided not to select a new sample because this would affect the site visit schedule. Instead, EPA

dropped the systems in the trust territories, and classified these systems as non-respondents when

calculating the sample weights. 

Sample Design

The CWSS analytical plan specified precision level targets for subpopulations of systems,

which required minimum sample sizes be achieved for each subpopulation. The precision targets for

each subpopulation were 95 percent confidence intervals of ± 10 percentage points for estimated

proportions. The domains of the population of interest for EPA are based on two characteristics of the

systems: 

1. The source of water. Systems that rely on ground water are distinguished from

surface water systems.

2. The size of the population served by the system. Eight size categories will be used: 

systems that serve less than 100 people; systems that serve 101 to 500 people; systems

that serve from 501 to 3,300 people; systems that serve from 3,301 to 10,000 people,

systems that serve from 10,001 to 50,000 people; systems that serve 50,001 to

100,000 people; systems that serve from 100,001 to 500,000 people; and systems

serving more than 500,000 people. 

The two water sources and the eight system sizes produce sixteen strata. 
124

A system is classified as a surface water system in SDWIS if any of its water is surface water. 

Ground water under the direct influence of surface water is classified as surface water. Systems that

rely on purchased water systems are included in the ground water strata because we assume the

characteristics of the water and the treatment requirements will be more similar to ground water than to

surface water. (While some untreated surface water is purchased, the majority is treated and therefore

more similar to ground water than surface water.) 

The sample is stratified to achieve two goals. First, stratifying the data allows us to draw

inferences about specific population domains. For example, EPA may wish to draw conclusions about

systems serving populations of less than 10,000 or 3,300. We can ensure that estimates of the subpopulations will meet the required levels of precision by drawing the necessary number of observations

for each stratum. 

The second goal achieved by stratifying the data is that we can increase the efficiency of our

estimates by grouping systems into relatively homogeneous strata. The strata were chosen to minimize

the differences among systems within strata, and to maximize the differences among strata. The results

of previous surveys indicate there are important differences in the way systems are operated and in their

finances across the strata selected. The operating characteristics and treatment requirements of ground

water systems tend to be different from surface water systems. The operating and financial

characteristics of large systems tend to be more complex than small systems. System management, and

the resources available to it, also may vary by system size. The regulatory impact models require

reasonably precise parameter estimates from each of these domains. The sample size in each domain

should be large enough to provide a sufficient number of completed questionnaires to obtain estimates

with reasonable precision. 

Table 2-1 shows the number of systems in the sample frame and the minimum sample size

required to obtain an estimate for a proportion of 50 percent with an error not exceeding ± 10

percentage points (except for a 1 in 20 chance) in each domain. (A 50 percent statistic was used

because the standard error is largest when the population percentage is 50 percent. The error will be

smaller for other population percentages.) Systems with populations served of over 100,000 were

selected with certainty.

Sample Selection

For Community Water Systems serving 3,300 or fewer people (small CWSs), a two-stage

sampling design was used to reduce field data collection costs. Field data collectors were sent to the

clusters of six systems at a time to collect data. The primary sampling unit (PSU) was a county or a

group of counties. (Each county with fewer than six small systems was combined with geographically

adjacent counties to form the primary sampling units.) At the first stage of sampling, a sample of 100

PSUs were selected with probabilities proportional to size. The measure of size was the number of

small systems in the PSU. A large PSU could be selected ("hit") more than one time. PSUs were re-
125

sampled to account for potential non-response. The over-sampling rate was determined based on

EPA’s experience with the 1999 EPA DWINS and the 1995 CWS Survey. States were provided

with a list of small CWSs in the counties selected, and EPA asked States to verify that the systems on

the list are active and serve populations of 3,300 or fewer.

To select the second stage sample of small systems, the overall selection rate for each small

system stratum was calculated as the target initial sample size in the stratum divided by number of

systems in the stratum. The expected frequency of selection was calculated for each PSU in the first

stage sample. For each PSU selected, the second stage selection rate for a stratum equaled the overall

selection rate for the stratum divided by the first-stage expected frequency of selection. That second

stage selection rate for a stratum was applied to the count of systems in that county to determine the

fractional sample size. The fractional sample sizes was converted to integer sample sizes using

stochastic rounding and with the constraint that the total integer sample size for a county hit equals six

systems. To measure composite sample size in selecting counties or PSUs, an “overall stratum

selection rate” was multiplied by the number of systems in the stratum in that PSU, and summed over all

strata in each primary sampling unit (county or group of counties). 
126

Table 2-1. Frame and Sample Sizes by Strata

Source of Water Population Served Frame Size

Required

Sample 

Ground 100 or less 14,972 95

101-500 16,025 95

501 - 3,300 12,341 95

3,301 - 10,000 3,300 92

10,001-50,000 1,921 89

50,001 - 100,000 260 60

100,001 - 500,000 126 126

More than 500,000 17 17

Surface 100 or less 538 88

101-500 789 91

501 - 3,300 1,551 93

3,301 - 10,000 988 91

10,001-50,000 970 91

50,001 - 100,000 215 74

100,001 - 500,000 189 189

More than 500,000 66 66

All 54,268 1,452

For systems serving populations of 3,301 – 100,000, the sample was obtained by drawing a

random sample of systems from the cleaned SDWIS frame, within each sampling stratum serving

populations of this size. Systems in these strata were oversampled to account for non-response. As

with the small systems, the over-sampling rate was based on EPA’s experience with the 1999 DWINS

and the 1995 CWSS. Systems serving populations of more than 100,000 were selected with certainty. 

The resulting increase in sample size is warranted for the following reasons: 
127

C Each of the larger systems has a more significant impact on the total costs and benefits

of regulations. 

C Because of the small numbers of systems in many of the larger strata, precision can be

increased at comparatively lower cost than it can be for smaller systems. Other things

being equal, doubling precision will quadruple sample size in strata with 5,000 systems

or more. Many of the larger strata, however, have only hundreds of systems. In a

stratum of 750 systems, one could double precision by only tripling sample size. In a

stratum of 200 systems, one could double precision by doubling sample size. 

A total of 1,870 systems were selected into the sample. The sample size by strata and the and

sampling rate are shown in table 2-2. 

2.1.3 Stratum Migration

Errors in the SDWIS frame classification of the water systems by population served and water

source introduces inefficiency in the sample design through a loss of sample size and/or by introducing

unequal sampling rates. Among the respondents, 87 percent reported the same population served

category as indicated by the frame. Just over 91 percent reported the same source as the frame. 

Population Served by the System

Table 2-3 compares the classification of systems by their population served using the population

data from the frame and from the systems’ responses to the survey. In all size categories, more than 80

percent of systems confirmed their original size category. Within each size category, over 96 percent of

systems were either in their original size category or in the adjacent class. While migration across size

categories is small, several systems reported to serve 3,300 or fewer people in the frame moved into

larger categories; 20 moved into the 3,301-10,000 category, and 4 moved into larger population

categories. Also, 19 systems moved into small system categories from the larger categories. 
128

Table 2-2. Sample Size and Sampling Rate by Strata

Source of

Water Population Served

 Sample

Size 

Sampling

Rate (%)

Ground 100 or less 128 0.9

101-500 124 0.8

501 - 3,300 124 1.0

3,301 - 10,000 155 4.7

10,001-50,000 152 7.9

50,001 - 100,000 116 44.6

100,001 - 500,000 126 100.0

More than 500,000 17 100.0

Surface 100 or less 94 17.5

101-500 85 10.8

501 - 3,300 90 5.8

3,301 - 10,000 145 14.7

10,001-50,000 144 14.8

50,001 - 100,000 110 51.2

100,001 - 500,000 194 102.6

More than 500,000 66 100.0

All 1,870 3.4
129

Table 2-3. Survey Respondents by the Frame-Based and Sample-Based Size Categories

Sample-Based PopulationServed Categories

Frame-Based Population Served Category

25-100 101-500

501-

3,300

3,301-

10,000

10,001-

50,000

50,001-

100,000

100,001-

500,000

Over

500,000

25-100 Count 142 13 0 0 0 0 1 0

Percent 91 8 0 0 0 0 1 0

101-500 Count 16 144 10 1 0 0 0 0

Percent 9 84 6 1 0 0 0 0

0501-3,300 Count 6 11 177 15 1 0 1 0

Percent 3 5 84 7 0 0 0 0

3,301-10,000 Count 1 0 19 139 10 0 1 0

Percent 1 0 11 82 6 0 1 0

10,001-50,000 Count 1 0 1 13 136 9 1 0

Percent 1 0 1 8 84 6 1 0

50,001-100,000 Count 1 0 0 0 4 108 4 0

Percent 1 0 0 0 4 92 3 0

100,001-500,000 Count 1 0 0 0 1 14 182 4

Percent 1 0 0 0 1 7 90 2

Over 500,000 Count 0 0 0 0 0 1 2 55

Percent 0 0 0 0 0 2 3 95
130

Source of Water

Table 2-4 shows the cross-tabulation of the frame-based and response-based water source

classifications. Approximately 86 percent of the systems classified as ground water systems in the frame

confirmed that status in the sample. Ninety-four percent of surface water systems in the frame were

also classified as surface water systems in the sample. 

Table 2-4. Survey Respondents by the Frame-Based and the Sample-Based Source

Categories

Sample-Based

Water Source

Frame-Based Water Source

Small Medium Large All

Ground Surface Ground Surface Ground Surface Ground Surface

Ground Count 323 42 146 12 123 19 592 73

Percent 88 12 92 8 87 13 89 11

Surface Count 9 164 10 163 15 220 34 547

Percent 5 95 6 94 6 94 6 94

Impact of Strata Migration on the Accuracy of Domain Estimates

The sample was designed to estimate a 50 percent statistic with a 95 percent confidence

interval of ± percentage points. One measure of the impact of the strata migration on the efficiency

estimates is to calculate the size of the confidence interval given number of observations in each stratum

for the sample collected. Table 2-5 shows the minimum sample required to estimate a 50 percent

statistic with a 95 percent confidence interval of ± 10 percentage points. The planned sample size is the

sample that would be needed if the frame had correctly identified all subdomain members. The

required sample size is the sample needed, given the inaccuracies in the frame. The table also shows

the half-width of the 95 percent confidence interval that results from the actual sample selected, given

the sample’s estimate of the number of systems in each subdomain. The increase in the half-width for

mid-sized ground water systems is modest. Because the sample was designed to collect data on all

systems with populations of more than 100,000, the width of the confidence interval for these systems

would have been zero. The width increased substantially for ground water systems in these strata and

slightly for surface water systems serving greater than 500,000 people categories due to the strata

migration, as the number of systems in these strata is larger than expected. It also increased for surface

water systems serving populations of more than 500,000. 
131

Table 2.5. Sample Sizes and the Impact on Precision of Estimates of Strata Migration

Source Population Served Required Planned

Half width of

95% Confidence

Interval

Ground 100 or less 95 95 0.100

101 - 500 95 95 0.100

501 - 3,300 95 95 0.100

3,301 - 10,000 93 92 0.101

10,001 - 50,000 91 89 0.101

50,001-100,000 70 60 0.111

100,001-500,000 125 73 0.074

Over 500,000 17 8 0.260

Surface 100 or less 79 88 0.094

101 - 500 85 91 0.096

501 - 3,300 90 93 0.099

3,301 - 10,000 88 91 0.098

10,001 - 50,000 87 91 0.098

50,001-100,000 66 74 0.092

100,001-500,000 191 257 0.000

Over 500,000 66 50 0.069

2.2 Weighting and Estimation

A sampling weight is attached to each responding water system record to (1) account for

differential selection probabilities, and (2) reduce the potential bias resulting from nonresponse. The

sampling weights are necessary for estimation of the population characteristics of interest. The sample

variance is then used to calculate 95 percent confidence intervals for the estimates. 

2.2.1 Derivation of Base Weight and Nonresponse Adjustment

The calculation of the sample weight reflects the complex nature of the sampling design. The

community water system sample consists of a stratified element sample of medium and large water

systems. Systems were stratified by water source and their population served. For small water

systems a two-stage cluster sample design was used. 

1. At the first stage geographic clusters (counties or county groupings) were sampled using

probability proportional to size sampling. The measure of size was a function of the

number of small systems in the cluster. 
132

B

N

n

h

h

h

=

B

P

N

n

mh

m

mh

mh

=

























1

2. Within clusters a stratified element sample of small systems was drawn. 

After the initial sample was drawn, it was decided to go back to some of the clusters and draw

additional small systems from specific strata to make up for a short fall in sample size due to a larger

than expected number of ineligible small systems. Also, sample clusters located in U.S. territories were

not included in the actual data collection for cost reasons and are treated as nonrespondents. 

The EPA SDWIS data file was used as the sampling frame for sample selection. Sixteen

sampling strata were defined based on systems’ population served and source of water; all weight

calculations use this sample stratum variable. 

Base weights

The first step was the calculation of a base sampling weight for each sample system. For the

medium and large systems the base sampling weight equals the number of systems in the stratum

divided by the number sampled from that stratum. In other words the base weight for the hth stratum,

Bh, is:

where Nh represents the number of systems in the stratum in SDWIS, and nh represents the number of

systems sampled from the stratum. 

For the small systems the base sampling weight equals the product of the reciprocal of the

probability of selection of the cluster times the reciprocal of the within cluster probability of selection of

the small system. For large clusters selected with certainty the cluster base sampling weight component

equals one. The reciprocal of the within cluster selection probability equals the number of small systems

in a stratum divided by the number selected from that stratum. The base weight for a sample system in

the hth stratum in the mth cluster is given by Bmh:

where Pm is the probability of selection of the mth cluster. 

Nonresponse adjustment

The second step in the weighting methodology was to make a unit nonresponse adjustment to
133

dh

h h

h

n r

n

=

+

Wh B

f

= hdh

Wmh Bmh h = d

rh

h

mhj

j R

mhj

j I

N

W B

h h

=

+

∈ ∈

∑ ∑

the base sampling weights. For each medium and large system stratum, the nonresponse adjustment

factor is equal to the ratio of the number of systems that completed the survey plus the number of

nonrespondents to the number of systems that completed the survey (i.e., the reciprocal of the stratum

response rate). Ineligible systems are not incorporated into the unit nonresponse adjustment. The

adjustment factor for the hth stratum is given by *h: 

Where rh is the number of refusals and other nonrespondents in the hth stratum. 

For the small system sample the unit nonresponse adjustment was not implemented within each

cluster because the sample sizes were too small. Rather the adjustment was carried out within each

small system stratum at the total sample (i.e., national) level. 

Final weights

The nonresponse adjustment factor *h was multiplied by the base sampling weight, Bh, to

obtain the nonresponse adjusted base sampling weight. The nonresponse adjusted base sampling

weight for the medium and large systems that completed the survey is the final weight for use in analysis. 

The nonresponse adjusted weights can be written as: 

for medium and large systems, and

for small systems. 

The final step in the weight calculations for small systems was a ratio adjustment to the SDWIS

data file count of small systems in each small stratum at the national level. This step was carried out

because the two-stage sample of small systems, drawn from 104 sample clusters, may not have the

same stratum distribution as the entire EPA data file of small systems. For each small system stratum,

the sum of the nonresponse adjusted base sampling weights for systems with a completed survey was

added to the sum of the base sampling weights for the ineligible systems. The count of small systems in

SDWIS was then divided by this sum. This yielded a ratio adjustment factor for each small system
134

Wmh W

f

mh h = r

stratum, Dh: 

Where: Rh is the set of systems that responded to the survey, and 

Ih is the set of systems sampled that were ineligible. 

j designates the jth sample system. 

For the small systems with a completed survey their nonresponse adjusted base sampling

weight was multiplied by the ratio adjustment factor to yield a final weight for use in analysis: 

2.2.2 Variance Estimation

The estimate of the variance must account for the sampling design. Weights are used to

produce estimates for the population as a whole – for example, the proportion of treatment facilities that

use a particular treatment practice, or the mean water-sales revenue of a system. Weights also affect

the standard error of the estimates, and therefore the confidence intervals. 

The 2000 CWSS sampling design was relatively complex; medium and large systems were

selected by strata; small systems were selected in clusters of counties (or, in some cases, groups of

counties) using a probability proportional to size sampling. This sampling design also affects the

estimate of the standard error. The stratification of the systems by water source and population served

will tend to reduce the overall sample variance, as systems within a stratum tend to be similar to each

other and different from systems in other strata. The clustering will likely increase the sampling

variance, as systems within a cluster may be similar to each other . This effect of clustering may not be

large; while systems within a county share some characteristics, the often are a diverse group in terms of

population served and water source, as well as revenue, expenses, and operating characteristics. But

ignoring the clustering may lead to an underestimate of the sampling variance, so it must be taken into

account. 

The treatment facilities in the sample were not selected independently; rather, they were

selected in clusters in a two-stage process. For medium and large systems, the stratified random

sample of systems were selected in the first stage; every treatment facility in each system was selected

in the second stage. Facilities in small systems were selected in a three-stage process: counties (or

groups of counties) were selected in the first stage; a sample of systems within each county was

selected in the second stage; every facility within each system was selected in the third stage. The

calculation of the sample variance of estimates regarding treatment facilities also must take into account
1See Cochran, W.G. 1977, Sampling Techniques, New York: John Wiley & Sons for amore

information about variance estimates.. 

135

( ) { ( ) ( ) ( )} $ $

$

$ $ $ $$

, V R $ $ $ $

X

= V Y − RCov Y X + R V X

1

2 2

2

d ( )

X

y Rx hij hij hij = −

1

$

$

this sampling design. 

Variance Estimator 

The variance is estimated using a first-order Taylor expansion. The variance is calculated in

Stata. The variance estimator is given by: 

where $ , the ratio of estimates of two population totals. is equal to , and $

$

R

Y

X

= Y$ w y hij hij

j

n

i

m

h

L h hi

= = =

∑ ∑ ∑ 1 1 1

is equal to . L is the number of strata, mh is the number of primary sampling units in X$ w x hij hij

j

n

i

m

h

L h hi

= = =

∑ ∑ ∑ 1 1 1

strata h, and nhi is the number of elements in the ith primary sampling unit in the hth strata. 

Most of the estimates produced in this volume are either means or proportions. A mean is

simply a ratio in which xhij is equal 1. A proportion is simply a mean in which yhij is equal to a 0/1

variable.1

Finite Population Correction

A finite population correction factor was derived for medium and large systems in the sample. 

The factor is the ratio of systems in the sample to the number of systems in each stratum. Because the

primary sampling units for small systems were selected with replacement, the finite population

correction factor is set equal to zero for small systems. 

To estimate the variance, we first define the following ratio residual:

We then define the weighted total of the ratio residual as 
136

zdhi whijdhij

j

nhij

=

=

∑

1

z

m

z dh

h

dhi

i

mh

=

=

∑

1

1

( ) ( ) ( ) V$ R$

f

m

m

z z h

h

L

h

h

dhi dh

i

nh

= −

−

−

= =

∑ 1 ∑

1

1

2

1

and the weighted average of the residual as: 

We can then define the variance estimate as: 

where fh is the finite population correction. 

The estimate of the variance is used to estimate 95 percent confidence intervals in the detailed

tables of this report. An implicit assumption is that the average values presented in each table are

normally distributed. When the estimate is based on a large number of systems, this will generally be

true; in cases where the estimate is based on a small number of systems, the assumption may not hold. 

The confidence interval in these cases may be larger than the mean itself. The confidence interval is not

adjusted in these cases; to compute the correct confidence interval requires examination of the empirical

distributions for each variable in the calculation and is beyond the scope of this study. 
137

3. SURVEY DESIGN AND RESPONSE

The survey was administered through site visits to small systems (those serving populations of

3,300 or less), and through a mail survey to medium and large systems (those serving more than 3,300

people). This chapter discusses the survey instrument, the processes for conducting the site visits and

distributing the questionnaires, as well as the process to assure sufficient response rates and the handling

of returned questionnaires. 

3.1 Questionnaire Design

The Cadmus Group, working closely with EPA staff responsible for regulatory development,

developed the questionnaire. The process began with a meeting of EPA staff to discuss their data

needs, distinguishing core needs required for regulatory development from other data needs. Based on

these discussions, some of the questions that were in the 1995 CWSS were eliminated from the 2000

questionnaire. Other questions – especially those focusing on treatment – were further developed. A

slightly modified version of the questionnaire was developed for systems that serve populations of over

500,000; this version of the questionnaire included additional questions on source and finished water

contaminant concentrations, and excluded questions that only would apply to small systems. The

survey instrument is in Appendix A. The questionnaire in Appendix A is a composite of the two

questionnaires used; the questions that are asked only of systems serving over 500,000 people or only

systems serving up to 500,000 people are noted. 

Cadmus worked with EPA on the wording and organization of the questionnaire. It was

responsible for the design and layout of the questionnaire form, and for documenting and incorporating

all revisions to the several design and test versions of the questionnaire. Throughout the design process,

the EPA project officer consulted with the full range of EPA regulatory and analytical staff, representing

expert advisors and future users fo the data, to identify and correctly present the broad survey topics

and specific survey questions to be included in the survey instrument. These covered such areas as

water production, storage, distribution, treatment, and cross connection control, as well as financial

information regarding water sales revenue, customer data, operating expenses, and capital investment. 

EPA went to great lengths to attempt to reduce the burden to respondents while collecting

complete, accurate, detailed data. EPA decided to conduct site visits to small systems because of the

difficulties they faced in responding to past Community Water System Surveys. EPA also established a

process to provide extensive technical assistance and guidance to recipients of the mailed questionnaire. 

As discussed in chapter 4, EPA conducted a pre-test of the questionnaire to identify questions that

posed potential problems for respondents. EPA also conducted a pilot test of the data collection

methods. As a response to both tests, EPA made several changes to the questionnaire, reducing the

scope of several questions. For example, as a result of the pre-test, the number of age and diameter

categories was reduced in the question regarding the length of the distribution system. was simplified. 
138

3.2 Data Verification

EPA forwarded the list of water systems selected in the sample to the states. For small

systems, the states were asked to verify that the systems were active systems serving up to 3,300

people, as well as the address, telephone, and the contact information. The states identified 27

systems that were not active Community Water Systems. To replace the systems that were inactive, 22

additional systems were selected from each of the clusters that contained inactive systems. Not every

inactive system could be replaced because each cluster did not have enough systems in the sample

frame to replace all the inactive systems. 

3.3 The Pilot Test

Approximately 50 systems were selected from the sample for a pilot test. Two clusters of small

systems were selected for site visits by senior Cadmus water system professionals. Ten systems

participated in the pilot test. (One system was inactive, and one refused to participate.) Approximately

40 systems serving more than 3,300 people received the questionnaire by mail. The pilot tested the site

visit and mail-out process, and the technical support system. The pilot systems were included in the full

sample. 

3.4 Site Visit Operations. 

Three contractors were selected to conduct the site visits. The contractors were: 

C International Studies and Training Institute, Inc., 

C Southwest Environmental Engineering, and 

C McNenny Environmental Engineering and Consulting. 

Cadmus also conducted several site visits. 

Cadmus trained the site visit staff. The training covered the survey, the information required

from the systems, and the data collection protocol. The training included on-site inspections with

Cadmus staff of a cluster of systems in the sample, as well as detailed instructions on the conduct of the

visit. 

The states were contacted ahead of time to confirm the systems in the sample and to review

information on the system contacts. Site visitors were told to let state contacts know they were in their

area and what they were doing, as a courtesy. The surveyor extended the opportunity to the states to

attend the survey. Otherwise, the surveyors were told to not burden the states with requests for

assistance. 
139

As part of the training, site visitors were instructed as follows: 

C The survey is voluntary and not to be misrepresented as mandatory. It is an

opportunity to provide information to be used by EPA to make sound, informed 

decisions and regulations.

C Obtain the operating and financial information for the same time period of time, if at all

possible

C If information is not available for the separate classes of system (for example, water

deliveries by customer class), then collect the totals (e.g., total deliveries). 

C Indicate the system has a treatment objectives only if the facility was “designed” for that

purpose. For example, if the facility was designed for particulate removal and removed

arsenic in the process, the surveyors were to only check particulate removal.

C Complete the sequence of treatment after a walk-through of the treatment plant. If

available, collect a schematic. 

C Operators on-call are not the same as on-site; therefore, if a system only has an

operator on-call, it should not be classified as having an operator on-site 24 hours a

day. 

C SCADA for process monitoring was defined as information on values (i.e. elevations,

pressures, pH, cl2, etc.). It was classified as process control if it had the capability to

automatically control equipment ( i.e. pump controls, feed equipment controls, pacing

control, etc)

C Related questions should be checked for consistency. For example, questions on water

produced should be consistent with deliveries and unaccounted for water. Water

delivered should be consistent with the number of customers and connections. 

C Collect a service area map or draw the service area on a map (USGS, MapBlast,

Microsoft, etc) for each system.

C The cross connection control program must be more than the plumbing code. The

program should be specifically designed as a backflow prevention/cross connection

control program.

C Financial data. If there is no other information, get the average annual bill

(question26). Again, if the information was not available in a manner that it could be
140

broken down into components, get totals.

C Collect financial reports if they are available and if the system will not break down the

costs as requested.

Several issues arose during the site visits that required consistent responses. They included: 

C If the system indicated that it merged with another system, the site survey was

conducted.

C If a system decreased in size so it was no longer a community water system, the site

visit was conducted to confirm the status.

C If the system grew so it was no longer a small system, the site visit was conducted and

data collected. 

Each site visitor was given a list of systems to visit. The site visitors contacted the systems to

schedule the on-site inspections; the site visitors were required at times to contact the state to confirm

contact information. Once on-site or in some cases prior to the site visit, the systems were provided

with an letter introducing the site visitor and explaining the survey. The site visitor inspected the system,

interviewed the staff, photographed the system (from source to delivery), and filled out the

questionnaire. The completed questionnaire, inclusive of the pictures, site map, and collected

information and reports, was then submitted to Cadmus. Senior staff at Cadmus reviewed all surveys

submitted by the site visitors to ensure the site visitors were filling out the questionnaire correctly and to

insure consistent responses from the 6 site surveyors. The questionnaires were then logged into the

tracking system as received and completed. 

During the site visits, Cadmus senior staff communicated with the site visitors via telephone and

e-mail to insure consistent and complete results. Group email was used to provide answers and

clarification to the site visitors questions. All site visitors received the same information.

Site visits were not done in Alaska or Hawaii. For Alaska, two clusters of small systems were

surveyed using a combination of telephone interviews with system, state regulatory, and EPA personnel. 

The remoteness and reluctance of some of the systems in Alaska made on-site visits infeasible. The

information that was collected from these system was abbreviated to promote response. The data

reflect the Alaska systems, but may not be easily compared to the remaining small system surveys.
141

3.5 Mail Survey Operations

Cadmus produced camera-ready versions of the two questionnaires, which EPA printed at its

facility. Cadmus produced three mailing information and control labels for each system’s questionnaire. 

Information for the mailing label was extracted from the sample frame and attached to the envelope for

mailing. A second label that included contact information, the mailing address, and a telephone number

was produced and attached to the questionnaire itself. This label explicitly instructed the respondent to

respond only to the sampled system when answering the questions. Both labels included a public

water system identification number (PWSID), in both alpha-numeric and bar-code. The third label

contained the toll-free telephone support line and e-mail information. Included in the envelope, along

with the questionnaire, was an introductory letter from the president of the Cadmus Group, a brief list of

instructions, and a pre-addressed pre-paid FedEx envelope for systems to return the completed

questionnaire. 

The questionnaires were mailed to approximately 1,200 community water systems over a 2 day

period. Each system then received a telephone call from the analyst at Cadmus responsible for that

system. The call informed the system of the survey, told them they would receive the questionnaire, and

gave the systems a name and telephone number to call with any questions. If a system did not receive

the questionnaire, the analyst responsible for that system sent them another copy of the questionnaire

via FedEx. The analyst continued to follow-up with each system until the system either responded to

the survey or refused to participate. The analysts provided technical assistance as necessary, and in

some cases filled-out the questionnaire through a telephone interview. 

As questionnaires were received from the water systems, Cadmus logged them into the on-line

tracking system. The analyst responsible for the questionnaire reviewed it for data quality and to

identify potential problems. When necessary, senior engineering or financial staff were consulted

regarding potential problems. If a problem or question could not be resolved by Cadmus staff, the

analyst contacted the Community Water System. When this initial review was completed, the

questionnaire was forwarded to senior staff for additional review. All changes to the questionnaires

were recorded in a permanent log. After the senior review was completed, the completed

questionnaire was forwarded to data entry. 

3.6 Data Entry

Upon review by the senior staff, all questionnaires were logged as completed, and sent to Abt

for data review and editing, and preparation for data processing. The questionnaires were then keyentered using 100 percent verified double-key entry. After entry, the data were run through automated

cleaning and editing programs that checked each variable for proper values and ranges, and checked

skip patterns. Items failing these checks were examined and either confirmed or corrected.

Questionnaires that reached this stage were considered to be entered and cleaned. (The data were

subject to further intensive checks as part of the quality assurance process, discussed in chapter 4.) 
142

Status reports were sent to the EPA project managers every two weeks during the data

collection effort. The report showed the number of questionnaires with each of the following status

codes: 

C Site visit appointments scheduled or questionnaires mailed

C Questionnaires re-mailed

C Inactive systems

C Questionnaires undeliverable

C Refusals

C Site visits completed/questionnaire returned

C Questionnaires reviewed and ready to enter into database

C Completed questionnaires entered into database

Table 3-1 presents an example of the information provided to EPA. 
143

Table 3-1. Example of Data from Status Report

Ground Water Systems

Population Served 25-100 101-500 501-

3,300

Subtotal,

25-3,300

3,301-

10,000

10,001-

50,000

50,001-

100,000

100,001-

500,000 >500,00 Subtotal,>3,300 Total

Sample selected 128 124 124 376 155 152 116 127 17 567 943

Sample needed to meet

precision requirements* 95 95 95 285 93 91 70 127 17 398 683

Appointments scheduled or

questionnaires mailed 113 110 121 344 153 151 115 126 17 562 906

Questionnaires re-mailed 0 0 0 0 26 28 22 30 4 110 110

System found to be

inactive 10 6 0 16 1 1 0 1 0 3 19

Questionnaires

undeliverable 2 0 0 2 2 1 0 2 0 5 7

Water systems that refused

to participate 1 1 0 2 30 15 22 25 1 93 95

Site visits complete/

questionnaires received 96 95 121 312 73 67 61 68 11 280 592

Questionnaires reviewed

for quality assurance and

ready to enter into database

91 94 121 306 49 44 36 40 3 172 478

Completed questionnaires

entered into database 0 0 0 0 0 0 0 0 0 0 0
Table 3-1. Example of Data from Status Report

144

Surface Water Systems

Population Served 25-100 101-500 501-

3,300

Subtotal,

25-3,300

3,301-

10,000

10,001-

50,000

50,001-

100,000

100,001-

500,000 >500,00 Subtotal,>3,300 Total

Sample selected 94 85 90 269 145 144 110 193 66 658 927

Sample needed to meet

precision requirements* 77 84 90 251 87 87 66 198 66 504 755

Appointments scheduled or

questionnaires mailed 65 63 85 213 143 138 106 189 66 642 855

Questionnaires re-mailed 0 0 0 0 14 21 14 24 11 84 84

System found to be

inactive 7 4 0 11 0 0 0 1 0 1 12

Questionnaires

undeliverable 0 0 2 2 0 2 0 2 0 4 6

Water systems that refused

to participate 0 1 0 1 15 20 14 20 4 73 74

Site visits complete/

questionnaires received 61 59 77 197 86 82 67 120 47 402 599

Questionnaires reviewed

for quality assurance and

ready to enter into database

59 57 77 193 59 63 41 82 27 272 465

Completed questionnaires

entered into database 0 0 0 0 0 0 0 0 0 0 0
Table 3-1. Example of Data from Status Report

145

Total, Ground and Surface Water Systems

Population Served 25-100 101-500 501-

3,300

Subtotal,

25-3,300

3,301-

10,000

10,001-

50,000

50,001-

100,000

100,001-

500,000 >500,00 Subtotal,>3,300 Total

Sample selected 222 209 214 645 300 296 226 320 83 1,225 1,870

Sample needed to meet

precision requirements* 172 179 185 536 180 178 136 325 83 902 1,438

Appointments scheduled or

questionnaires mailed 178 173 206 557 296 289 221 315 83 1,204 1,761

Questionnaires re-mailed 0 0 0 0 40 49 36 54 15 194 194

System found to be

inactive 17 10 0 27 1 1 0 2 0 4 31

Questionnaires

undeliverable 2 0 2 4 2 3 0 4 0 9 13

Water systems that refused

to participate 1 2 0 3 45 35 36 45 5 166 169

Site visits complete/

questionnaires received 157 154 198 509 159 149 128 188 58 682 1,191

Questionnaires reviewed

for quality assurance and

ready to enter into database

150 151 198 499 108 107 77 122 30 444 943

Completed questionnaires

entered into database 0 0 0 0 0 0 0 0 0 0 0

Note: includes systems that were in the pilot test. 

* Systems serving populations of over 100,000 are sampled with certainty. 
146

3.7 Survey Response

The data collection effort was closed out October 31, 2001. Of the 1,807 systems included in

the sample, 1,246 responded to the survey. The overall response rate was 67 percent. Table 3.2

shows the response rate by strata. Excluding the trust territories, the overall response rate was 69

percent. 

Table 3-2. CWSS Responses and Response Rate by Strata

Source of

Water Population Served

Completed

QuestionnairesResponse

Rate (%)

Ground 100 or less 107 83.6

101-500 106 85.5

501 - 3,300 124 100.0

3,301 - 10,000 77 49.7

10,001-50,000 70 46.1

50,001 - 100,000 62 53.4

100,001 - 500,000 69 54.8

More than 500,000 11 64.7

Surface 100 or less 61 64.9

101-500 62 72.9

501 - 3,300 83 92.2

3,301 - 10,000 91 62.8

10,001-50,000 82 56.9

50,001 - 100,000 70 63.6

100,001 - 500,000 123 63.4

More than 500,000 48 72.7

All 1,246 66.6
147
148

4. QUALITY ASSURANCE AND PEER REVIEW

The quality assurance plan for the CWSS encompassed specific measures to check and ensure

the validity of the survey data from data collection through data processing and analysis, as well as

measures to assure the quality of other survey components. A Quality Assurance Project Plan (QAPP)

was developed for the survey and was approved prior to the start of data collection. The Office for

Environmental Information reviewed the methodology and the data presented in the body of the report. 

The report results and statistical methods also were peer reviewed by subject matter experts. Drafts of

the questionnaire were reviewed by Diane Moles, from the Iowa Department of Natural Resources, in

Des Moines, IA, and James K. Cleland of the Drinking Water and Radiological Protection Division of

the Michigan DEQ in Lansing, MI. OGWDW also consulted with Robert W. Mann of the Water

Supply Engineering Bureau of the State of New Hampshire’s Department of Environmental Services. 

Finally, the sampling design was reviewed by senior statisticians at as part of the external QAPP

review, as well as by Cadmus, Abt , and within EPA; it is the same basic design used for the 1999

DWINS. 

Section 4.1 discusses the questionnaire pre-test and the survey pilot test. Section 4.2 presents

the measures taken to assure the quality of the statistical sample. Section 4.3 discusses the quality

assurance procedures used during the data collection effort. Section 4.4 describes the data processing

quality assurance procedures. The last section describes the quality assurance steps taken during the

preparation of this report. 

4.1 Draft Questionnaire Pre-test and Survey Pilot Test

A significant component of the survey quality assurance plan was to thoroughly test the

questionnaire design, the survey design, and data collection procedures prior to implementing the full

study. Confirming the validity and effectiveness of these designs, or revising them when the tests

revealed problems, errors, or difficulties, led to design and process improvements that would have a

positive effect on the quality of the survey in such areas as data reliability, data completeness, accuracy

of the sample frame, and response rates. 

4.1.1 Pre-test

When the initial data collection objectives had been identified and the questionnaire shaped into

a working draft instrument, EPA conducted a pre-test of this draft with 7 water systems in New

England of various sizes, including ground and surface water systems. The pre-test participants were

recruited with the assistance of Ray Raposa of the New England Water Works Association. The main

objective of the pre-test was to gauge the respondents’ reactions to the questionnaire itself. The test

did not address any of the actual survey operations and response rate issues that would later be tested

in the full-scale pilot test. 
149

The recruited systems received the questionnaire in July, 2000. EPA then convened a focus

group meeting of the 7 water systems, facilitated by survey research staff from Abt Associates and

Cadmus. The focus group explored questions regarding comprehensibility, use of clear and

appropriate terminology, provision of suitable response categories, and questionnaire layout. The focus

group also discussed respondents’ ease or difficulty in providing answers, their immediate knowledge of

or access to information requested by the questionnaire, and their overall reaction to the survey. 

Overall, the focus group felt the questionnaire was clear and relatively easy to follow. As a

result of the pre-test, some questions were re-worded, and others were shortened. Otherwise, the pretest found no systematic problems in the respondents’ ability to provide answers to the questions. 

4.1.2 Pilot Test

A full scale pilot test was conducted in April and May, 2001. The pilot tested the questionnaire

and the major operational components of the survey design. The results of the pilot, along with the final

version of the questionnaires were delivered to EPA in May, 2001. The full on-line tracking system

was developed during the pilot, and the mail-out and receipt logging procedures were finalized. 

Twelve small systems and 42 medium, large, and very large systems were selected from the full

sample for use in the pilot. Of these, 10 of the small systems and 26 of the medium, large, and very

large systems responded. The response rate was consistent with the target rate for the survey as a

whole. 

As a result of the pilot, modest changes were made to the mail-out process and the instructions

for systems. The pilot also resulted in changes to several questions in the questionnaires. Questions 19

(length of distribution mains) and 32 (capital improvements) were simplified. Modest changes were

made to several other questions to clarify the question. The pilot also finalized the site visit protocols,

and identified issues that needed to be addressed when training the site visitors. 

4.2 Sampling Quality Assurance

Quality assurance of the sampling process for the CWSS involved three principal areas: 

C Development of the sample frame

C Sampling specifications, and

C Use of software designed to draw complex samples. 

Development of the Sample Frame. EPA conducted an extensive review of the data used

for the sample frame. By starting with the data used for the 1999 DWINS frame, the 2000 CWSS

was able to take advantage of the extensive data verification effort undertaken the 1999 DWINS. The

1999 DWINS frame was updated with data collected through the survey. This updated frame was
150

then compared to the data in SDWIS in the first quarter of 2000 to identify systems that were either

added or removed from SDWIS since the DWINS was completed. The development of the frame is

discussed in detail in section 2.1. 

Sampling Specifications. In order to carry out the sampling processes, the survey statisticians

prepared detailed specifications that served as directions for performing the sampling and as a

permanent documentation of the process. The sampling plan was documented in both the supporting

materials for the Information Collection Request submitted to the Office of Management and Budget,

and in the Quality Assurance Project Plan. The specifications ensured the sample was drawn in

conformity with the sample design and in a statistically valid manner. 

Sampling Software. The CWSS sample of systems serving up to 3,300 people was drawn

using SAS-based program designed to draw two-stage cluster samples of this type. The same program

was used to draw the 1999 DWINS. The sample of systems serving population s of 3,301 to 100,000

was a stratified random sample and was drawn using Stata-based program to select random samples. 

4.3 Data Collection Quality Assurance

Each component of the CWS survey was implemented pursuant to detailed written

specifications that clearly stipulated how the design was to be implemented. 

Questionnaire Design

C The various drafts of the questionnaires were the product of close review and

comments by EPA, Cadmus, and outside reviewers. Improvements also were made as

a result of the pre-test and pilot test. 

C Questionnaire version control was maintained through the various drafts by handwriting all changes onto the hard copy master of the current version. After the changes

were made to the master word processing file, the previous hard copy version was

filed. Each version was dated and serially numbered. 

C The questionnaire form was designed to clarify and simplify for respondents the

provision of the highly detailed and complex data required for the survey. Graphic

devices were used to make the form clearer and simpler to use. The devices included

type fonts and sizes, borders, and text boxes. 

C Because of the difficulties small systems have with filling out complex questionnaires like

the CWSS, site visitors were sent to small systems to ensure the questionnaires were

filled out correctly. 
151

Mail Data Collection

C Workers preparing the questionnaire for mailing were provided with detailed written

specifications for the job and were supervised by a mail operations manager. 

C Mail clerks worked in tandem to produce the packages to be mailed to each

respondent. One clerk applied identification labels and assembled the packet; the

second applied the corresponding address label to the mail out envelope. This

procedure effectively provided a 100% check that the mailing and questionnaire labels

were for the same water system. 

C A survey manager conducted spot checks of the questionnaires before they were

sealed to ensure the respondent was receiving the appropriate form and that the

address label and CWS information label matched. 

C The prepared questionnaires were counted prior to mailing to verify that the correct

number of questionnaires were mailed. 

C Each recipient of the mailed questionnaire was assigned an analyst who maintained

contact with the water system throughout the survey. The analysts provided reminder

calls and technical support to the systems. They also reviewed the data as it was

received, following up with the system if there were any questions. 

C Senior survey managers reviewed at least the first 25 surveys received to ensure

analysts were using consistent procedures for each survey. 

C The on-line tracking system ensured proper tracking and control of all questionnaires

from the point of sampling until the data were entered and cleaned. In addition to

supporting overall management of the project, the periodic status reports identified

response rate problem areas which enabled Cadmus to take appropriate follow-up

measures. 

Site Visits

C Extensive training was provided to the site visitors, including on-site training at a cluster

of small systems. 

C Detailed instructions were provided to each site visitor regarding the conduct of the onsite surveys. 

C Regular contact was maintained with all site visitors. Site visitor questions and Cadmus
152

responses were sent to all site visitors to ensure each received complete and consistent

information. 

C Each completed survey was reviewed by Cadmus staff as it was received. Follow-up

instructions were provided as needed. 

4.4 Expert Review of Responses

Each questionnaire was subjected to a multi-level, detailed review by Cadmus staff as it was

returned by the systems. Cadmus reviewed the questionnaire for completeness and internal

consistency. Systems were called if key questions were not answered or if answers were inconsistent

or unclear. 

Upon receipt of the completed questionnaire, the Cadmus analyst responsible for the system

reviewed the survey. They identified missing information and questions or potential problems with

responses. The analysts were provided training on how to evaluate a completed questionnaire, as well

as written guidance for reviewing the responses. The written guidance included rules-of-thumb for

internal consistency checks; these guidelines helped the analyst compare questions and identify

inconsistent answers. For example, guidelines were provided on average annual water consumption

per household, which were used to compare annual water production with the number of connections

reported. 

Guidelines were provided regarding follow-up questions for the system. If essential data on

system finance, treatment, and production were missing, or if inconsistencies could not be resolved,

analysts contacted the system. If detailed information was not available (e.g., revenue by customer

class), analysts attempted to collect more aggregate-level data (e.g., total water sales revenue.) 

Analysts worked with the systems to resolve inconsistencies. Senior staff contacted systems when

difficult issues arose. Changes to the questionnaire were documented and logged. 

The analysts review of the surveys was itself reviewed by senior survey staff. Senior survey

evaluated the analysts’ reviews at the beginning of the review process, and and provided feedback to

the analysts. Senior staff and water system experts provided information and answered questions

throughout the data collection period. 

Upon the completion of the analyst’s review of a questionnaire, the completed questionnaire

was then reviewed by Cadmus water system experts. Each question in the survey was subject to

review. The expert review focused on the validity of the responses to each question (e.g., checking that

the treatment sequence is logical), consistency across quesitons (e.g., the treatment practice is

consistent with the treatment objectives), and that questions were answered and reviewed consistently

across by water systems. Any further changes were documented and logged. 
153

4.5 Data Processing Quality Assurance

The completed surveys were edited and entered into an electronic database.. The electronic

data were then imported into a hierarchical database for distribution, and a statistical package for

detailed analysis. Procedures were in place at every step to maintain the integrity and quality of the

data. 

4.5.1 Manual Editing, Coding, and Data Entry

Following the expert review, the questionnaires were subjected to a 100 percent editing review

in preparation for entering the data. This editing process examined every response field on every form,

to check skip patterns, clarify handwriting that would be difficult for the data entry staff to read,

standardize the recording of quantitative data, and identify any potential problems, such as marginal

notes or potential order-of-magnitude reporting errors in the volumetric questions. General protocols

were developed to guide the data preparation staff in reviewing the forms and in handling generic

problems. Data Preparation supervisors performed a 100% quality control review of edited forms

before they were data entered. During the editing process any questions, including the creation of

open-ended codes, that could not be answered by the general protocols were passed on to Cadmus by

staff at Abt Associates for final decisions. The editing protocol was updated to reflect coding decisions. 

After the initial edit, the questionnaires moved to the data entry process. Each form was

entered with 100 percent verification, that is, using independent double key entry. The automated data

entry program was customized to each form. 

As the data were entered, the batches of entered records passed through a data cleaning

process, consisting of standard computer edits that examined each variable for conformity to

appropriate values or data ranges and also checked the small number of skip patterns that existed in the

survey instruments. A report identified each variable for each case that failed any of these tests. A data

preparation supervisor then examined the original questionnaire forms to determine whether the

anomaly occurred in the original data and, if so, whether to confirm it as correct or to refer to Cadmus

for resolution as described above. The standard computerized edits were repeated for all the data until

no cases failed the edits, except for any that had been specifically confirmed as valid outliers during a

previous review. 

After all questions were edited, entered, and cleaned to the degree permitted by these

processes, the resulting keyed data passed to a process of detailed automated logical edits that enabled

expert staff to conduct a highly focused review of data values and relationships. 
154

4.5.2 Automated Data Validation Checks

In preparing the final database, EPA, Cadmus, and Abt designed, produced, and analyzed a

series of computer validation checks. These checks were run on the full survey database after the data

were entered and passed the standard computer edits for values and ranges on a variable-by-variable

basis. The checks included the following: 

C Distribution frequencies for all categorical variables; 

C Distribution frequencies for all continuous numerical variables formatted into four

categories (non-zero responses, zero responses, legitimately skipped, and missing);

C Univariates for each continuous variable; 

C Item-specific cross-tabulations of categorical variables; 

C Item-specific cross-univariates of continuous data; and 

C Item-specific advanced logic edits. 

4.5.3 Database Quality Assurance 

The final, clean survey database represented the product of the various review, editing, data

entry, and data validation steps described above. Once the database was prepared, there were a

number of subsequent data processing steps required to create a variety of files suitable for analyses

and tabulations for the final delivery of a permanent database to EPA. The principal steps included: 

C Appending needed variables from external files, including sample and contact

information from SDWIS. 

C Analyzing the hard copy questionnaires and the frequency distributions of continuous

and categorical variables to devise rules for handling missing data. 

C Zero-filling blank responses. A detailed series of rules was developed for assessing

blank responses and determining whether to regard these as zeros or missing values. In

general, blank quantity fields were treated as zero, except when there was external

evidence in a logically related item that the response should not be zero. A detailed set

of programming specifications was designed to implement these rules. 

C Creating new derived variables from the survey data to categorize systems into strata

comparable to the original sampling strata but based on the final survey responses
155

rather than the SDWIS data. 

C Attaching the sample weights to the analytical file. 

C For the final delivery of the database to EPA, deriving and attaching the numerous

composite variables created for the production of the analytical tables in this report. 

Each step was planned in advance. Detailed specifications were written to guide the

programming and data processing needed to perform each step. In addition to these specifications, the

processing of files and flow of data throughout these steps were planned, controlled, and documented

through data flow diagrams. The diagrams are schematic representations of how files, data record,

data elements, and individual data point values are handled, combined, extracted, and moved from one

stage to the next. These diagrams are crucial quality assurance tools to help ensure that programmers

and systems analysts have aclear an common understanding of the entire process of data management, 

that the processing stages fit together in a logical order and accomplish the intended objectives, and that

there is an unambiguous audit trail of the condition of the data at each stage. 

Version control was maintained for all computer programs, an interim stages of all data files

were permanently archived. This meant that when changes were made to a program or process, it was

clear which was the current version and it always was clear of sequential changes that had been made

from one version to the next. It was always possible to restore any earlier version in full or to merge

selected data from the old version to the new version. 

The combination of the processing specifications, data flow diagrams, version control, and data

archiving ensured that no process was irreversible, that it was always possible to recover from any

deliberate or inadvertent changes to the data, and that the characteristics of the survey data were fully

known at each processing stage. 

4.5.4 Tabulation Quality Assurance 

The tabulations of the results presented in the tables in this report are varied and complex.

Rather than being a simple presentation of individual survey variables, each table usually presents the

results of multiple calculations involving several survey variables. Many tables present several such

results in a single table. There often were several different ways of defining or calculating an item of

interest, and sometimes there were different direct or derived sources of data for the calculation

available on the survey database. Hence, the following steps were taken to help assure that each table

accurately summarized and presented the data contained in the final survey database. 

C Identify important, relevant, and useful information that could be developed from

analyses of the survey data;
156

C Design each table to effectively present the results or to juxtapose related results in the

same table; 

C Clearly describe the contents of each table; 

C Define in detail the variables, values, formulas, and derivations that went into each

calculation; 

C Prepare clear and detailed data processing specifications for carrying out the

tabulations according to the calculation definitions; 

C Develop computer programs to process the data pursuant to the tabulation

specifications; 

C Review the initial tabular output for: 

– Consistency with the design of the table of contents; 

– Conformity with the definitional and programming specifications; and

– Reasonable agreement with expected valuesbased on external measures and

expert knowledge of water system operations and finance; 

C Review definitions, specifications, programs, and underlying data for tabulations

exhibiting data anomalies or outliers; 

C Review any definitions, specifications, or programs if the review process identifies

errors or the need for modifications to previous decisions; and 

C Repeat previous tabulation quality assurance steps and re-run tabulations until no further

unacceptable data anomalies are found. 

The tabulation process was fully automated, from the underlying source data through all

processing stages to the final formatted tables. There were no intermediate stages requiring manual

transfer or entry of data from one stage to the next. This eliminated human transcription error. Of

equal importance, it also expedited the process of successive iterations of the tabulations during the

quality review process, as each time a table was produced the output data automatically were

transferred into the same final table form as on the previous iteration. This ensured that any new

anomalies identified in later iterations did not result from transcription errors, and allowed the review

staff to focus their investigations on the table data, specifications, and programs. 
157

4.6 Quality Assurance During Report Preparation

EPA requested comments on the survey from several independent reviewers. EPA consulted

with Jeanne Bailey in the office of Regulatory Affairs at the American Water Works Association in

Washington, DC. Drafts of the questionnaire were reviewed by Diane Moles, from the Iowa

Department of Natural Resources, in Des Moines, IA, and James K. Cleland of the Drinking Water

and Radiological Protection Division of the Michigan DEQ in Lansing, MI. EPA also consulted with

Robert W. Mann of the Water Supply Engineering Bureau of the State of New Hampshire's

Department of Environmental Services. As noted in the introduction to this part of the report, EPA’s

Office of Environmental Information reviewed the data presented in this report to ensure the findings

were appropriately described and presented. Additional peer review was provided by Jan Beecher of

Michigan State University and John Petersen of George Mason University. 
158
159

Appendix A

Community Water System Survey 

Questionnaire
160
United States

Environmental Protection Agency

SURVEY OF SMALL, MEDIUM, LARGE, 

AND VERY LARGE 

COMMUNITY WATER SYSTEMS

(Composite of questionnaire sent to small, medium, and large systems, 

and to very large systems)

OMB No. 2040-0227

Expiration date: 2/29/04
Please return this questionnaire in the enclosed Federal Express envelope

or mail to: 

EPA Community Water System Survey

c/o The Cadmus Group, Inc.

135 Beaver St., Suite 2

Waltham, MA 02452

Participation in the survey is voluntary. However, as a matter of policy, EPA will not disclose the identity of any

respondent to this questionnaire, nor the identity of any participating water system. While no respondent has ever

claimed that the information asked for in this survey contains confidential business information (CBI), EPA will offer

you the opportunity of claiming CBI in the event that we receive a Freedom of Information Act request for any data

that would identify you or your system. It should be noted, however, that EPA has never received a Freedom of

Information Act request for such information in prior surveys. 

The public reporting and record keeping burden for this collection of information is estimated to average 2.27 hours

per response or to range from 1 hour to 4 hours per respondent annually. Burden means the total time, effort, or

financial resources expended by persons to generate, maintain, retain, or disclose or provide information to or for a

Federal agency. This includes the time needed to review instructions; develop, acquire, install, and utilize

technology and systems for the purposes of collecting, validating, and verifying information, processing and

maintaining information, and disclosing and providing information; adjust the existing ways to comply with any

previously applicable instructions and requirements; train personnel to be able to respond to a collection of

information; search data sources; complete and review the collection of information; and transmit or otherwise

disclose the information. An agency may not conduct or sponsor, and a person is not required to respond to, a

collection of information unless it displays a currently valid OMB control number. The OMB control numbers for

EPA's regulations are listed in 40 CFR Part 9 and 48 CFR Chapter 15. 

If you wish, you may send comments on the Agency's need for this information, the accuracy of the provided

burden estimates, and any suggested methods for minimizing respondent burden, including through the use of

automated collection techniques to the Director, Collection Strategies Division, U.S. Environmental Protection

Agency (2822), 1200 Pennsylvania Ave., NW, Washington, D.C. 20460; and to the Office of Information and

Regulatory Affairs, Office of Management and Budget, 725 17th Street, NW, Washington, DC 20503, Attention: Desk

Officer for EPA. Include the EPA ICR number and OMB control number in any correspondence. Do not send the

completed survey to this address.
Dear Owners and Operators of Community Water Systems:

The United States Environmental Protection Agency (EPA) is conducting a national survey of drinking water

systems using the attached questionnaire. About 1,500 water systems have been randomly selected to participate in

this survey, and yours was one such system. This survey is conducted approximately every five years, the last one

being in 1995. We are sending you this questionnaire because you were identified in your state's database (State

Drinking Water Information System) as the most appropriate person to provide information about your water system. 

Participation in the survey is voluntary.

This survey will accomplish a number of important objectives. First, it will give us current data that will allow us to

better consider the costs and benefits to water systems when we develop new national drinking water regulations. It

will also allow us to measure the impact of drinking water regulations that have been put in place since the last

survey. This, in turn, will help us determine more affordable approaches to drinking water treatment. Furthermore,

the answers you provide in this questionnaire will help us in developing more effective programs to safeguard our

nation's drinking water, provide guidance to the states and measure the effectiveness of programs already in

existence, such as the Drinking Water State Revolving Fund. 

As we have done in the past, EPA will only make use of the information you provide when it has been aggregated

with the responses of many other water systems in the same size category as yours. We will never disclose your

name or the name of your water system in any public documents. Please see the inside cover of the questionnaire if

you'd like more details on how your privacy will be protected.

Answers to this questionnaire will help EPA to understand your circumstances better than any other single tool we

have. If you have ever wanted to have a larger say in the development of national rules that could directly effect

you and your water system, providing answers to this questionnaire is an important contribution. Because only

1,500 of you are being asked to speak for over 50,000 other systems, your voice is that much more important and will

carry that much more weight. If you have ever felt that Federal regulators don't understand your situation, then

please take this opportunity to tell us, in detail, just what your situation is. It will make a difference. 

Sincerely,

Brian C. Rourke

Program Analyst

Standards and Risk Management Division
Please respond about:

Please return you completed questionnaire in the enclosed 

pre-paid Federal Express envelope by July 13, 2001
Page 1 of 22

2000 Community Water Systems Survey

Small, Medium Large / Very Large Systems Questionnaire

GENERAL INSTRUCTIONS

This questionnaire asks two preliminary questions and then is divided into two parts. 

PART I – OPERATING CHARACTERISTICS (Questions 3 – 25); and

PART II – FINANCIAL CHARACTERISTICS (Questions 26 – 32). 

Please complete the questionnaire. 

Make a copy of the completed questionnaire for your records before sealing it in the enclosed envelope. 

Please include a map of your service area or delineate your service area on the enclosed map. 

[VERY LARGE SYSTEMS: ]

Please enclose a schematic of your system, site plans of your treatment facilities, and the latest available financial

report. If the schematics, diagrams, financial or other reports contain the information requested by a question,

you may refer to the documentation rather than fill out the question. 

[SMALL/MEDIUM/LARGE SYSTEMS]:

Your are strongly encouraged to enclose schematics, diagrams, financial reports, or other information that will

help provide a complete picture of your water system. If schematics, diagrams, financial or other reports contain

the information requested by a question, you may enclose and refer to the documentation rather than fill out the

question.

If you require more space to answer an question than is provided, please record the information on a photocopy

of the question or use a blank sheet of your own. 
Page 2 of 22

1. Please provide the name, title, and telephone number of the most knowledgeable person to contact for

information on: 

(A) Part I – Operating Characteristics

Name: Title:

Tel. No. Fax No.

e-mail:

(B) Part II – Financial Characteristics

(Write “SAME” if same as above)

Name: Title:

Tel. No. Fax No.

e-mail:

2. This survey will ask you to provide operating and financial information for your public water system for the

most recent 12-month period for which data are available. Please specify below the end dates for which data are

provided. 

A. Operating information ...................................... / /

 (mm / dd / yy)

B. Financial information ...................................... / /

 (mm / dd / yy)

Part I – Operating Characteristics

For Part I of the survey, please use the period indicated in Question 2(a) to report “last year’s”

operating data. 

3. Please classify your water system using the following criteria (circle one). 

Owned or operated by a government or 

public agency (including government-owned systems that hire a

private company to operate the system) ........................ 1

Owned privately and operated for profit primarily as a 

water business ........................................... 2

Owned privately and not operated for profit (e.g., a homeowners

association or a non-profit cooperative) ....................... 3

Owned privately and operated as a necessary 

part of another business (e.g., a mobile home park) ............... 4
Page 3 of 22

4. If your system is owned or operated by the government, please select one of following that best describes the

form of government (circle one). 

A local or municipal government (e.g. towns, townships, cities,

counties, boroughs, parishes, and special districts) ............... 1

State government ......................................... 2

The Federal government .................................... 3

Some other government 

(Please specify) 4

A. PRODUCTION and TREATMENT

5. What was the amount of water that was produced and delivered to each of the following customer categories

during the last year [as defined by your answer to Question 2A]? (In millions of gallons. Note: if you cannot

distinguish among the different types of non-residential customers, enter the total for your non-residential

customers in line c.4.)

Customer Type Total

a. Sold to other public water suppliers:

1. Treated water ................................ Million Gallons/Yr.

2. Untreated water .............................. Million Gallons/Yr.

b. Residential .......................................... Million Gallons/Yr.

c. Non-residential

1. Commercial/industrial ......................... Million Gallons/Yr.

2. Agricultural ................................. Million Gallons/Yr.

3. Other (specify) Million Gallons/Yr

4. Subtotal, non-residential ........................ Million Gallons/Yr

d. Unaccounted for water not included above (including

uncompensated usage and system losses) .................. Million Gallons/Yr 

e. Total, all customer types (including unaccounted for water) .... Million Gallons/Yr

6. Provide the name of each public water supplier included in the response to Question 5a, above.

a. Treated water

b. Untreated water
Page 4 of 22

7. How much of the water reported in Question 5 came from each of the following sources during the twelve month

period reported in Question 2A ? (in millions of gallons; answer ‘none’ if a source does not apply).

a. Surface water (non-purchased) (including Ground Water Under the 

Direct Influence of Surface Water) ........................... Million Gallons/Yr.

b. Ground water (non-purchased) .............................. Million Gallons/Yr.

c. Purchased water

1) Treated water ....................................... Million Gallons/Yr.

2) Untreated water ...................................... Million Gallons/Yr.

d. Other (specify) Million Gallons/Yr.

e. Total ............................................... Million Gallons/Yr

8. What was the maximum daily water production from all sources for this 

utility over a single 24 hour period during the twelve month period 

reported in Question 2A? ................................... Million Gallons/day

The following definitions of the components of a water system are used in this survey. Figure 1 is

an example of a schematic of a water system, showing water sources, treatment plants,

transmission lines, and the distribution system. 

Please refer to these definitions and the schematic for an explanation of the terms used in

questions 10 through 18. Please submit diagrams or schematics, using figure 1 as a guide.

Please note that the identifier numbers used in the questions do not refer to specific items in the

schematic. For example, use ‘S1' to refer to your first surface water source, regardless of whether it

is a flowing stream, as depicted in the schematic, or another surface water source.
Page 5 of 22

Term Definition

Code in the

Schematic 

Surface water

intake

A surface water intake refers to the transmission of untreated water from a

surface water source (flowing stream, lake, reservoir, or ground water under the

direct influence of surface water) to a water treatment plant at the utility (see

accompanying diagram).

S1, S2

Ground water

intake 

A ground water intake refers to the transmission of untreated water from one or

more wells to a water treatment plant or directly into the distribution system.

Where the water from multiple wells flows through a common pipe prior to entry

into the treatment plant or distribution system, the combined flow is considered

one ground water intake (see accompanying diagram).

G1 – G4

Purchased

water intake

A purchased water intake refers to the transmission of water from the seller’s

utility to a water treatment plant or directly into the distribution system of the

purchaser’s utility.

P1, P2

Water

treatment plant 

A facility where water is filtered, disinfected, and/or otherwise treated prior to its

transmission into the distribution system (or its conveyance to another

purchasing water utility). For the purposes of this survey, simple disinfection

only or pH adjustment prior to entry into the distribution system are considered

to be a water treatment plant. 

WTP 1, 

WTP 2

Entry point An entry point is where treated or untreated potable water enters into the

utility’s distribution system. 

E1 – E4

Figure 1: Sample Diagram of Intakes, Treatment Plants, and Entry Points
Page 6 of 22

9. Please draw your schematic here or submit a schematic on a separate sheet of paper.
Page 7 of 22

10. Provide the following information for the surface water, ground water, and purchased water intakes for this

utility: MGD refers to millions of gallons daily. If the source is used on a seasonal basis, the average daily

amount is for the months in which water is drawn from the source. 

A. Surface Source.

Surface

water

intake

identifiers

What is the source type for each

surface water intake? (circle the

appropriate number) Is this a

seasonal

source?

(Circle 1

for yes

and 2 for

no)

Yes No

What was the

average daily

amount of water

drawn from each

surface water

intake during the

reporting period

in Question 2A? 

(MGD)

What is the estimated

potential maximum

daily amount of water

that can be drawn

from each surface

water intake, given

water availability

constraints only (e.g.

source capacity

contractual

obligations, permits,

or legal constraints)?

(MGD)*

What is the estimated

potential maximum

daily amount of water

that can be drawn from

each surface water

intake, given current

pumping and

equipment constraints

only (e.g. system

components and

physical constraints)?

(MGD)

Flowing

stream

Reservoir

or lake

Groundwater

under the

direct

influence

of surface

water

S1 1 2 3 1 2

S2 1 2 3 1 2

S3 1 2 3 1 2

S4 1 2 3 1 2

S5 1 2 3 1 2

* If not limited enter “no limit” here. Q10A Totals

B. Ground water source.

Ground

water

wells

How many

individual

wells

supply

each

ground

water

intake?

[Very

Large

Systems

Only]:

What is

the

average

well

depth? (In

feet)

[Very Large

Systems

Only]: Is the

intake a

confined

aquifer?

(Circle 1 for

yes or 2 for

no e.g.

unconfined)

Yes No

Is this a

seasonal

source?

(Circle 1 for

yes and 2 for

no)

Yes No

What was the

average daily

amount of water

drawn from each

groundwater well

during the

reporting period

in Question 2A?

(MGD)

What is the

estimated potential

maximum daily

amount of water

that can be drawn

from each

groundwater well,

given water

availability

constraints only

(e.g. source

capacity

contractual

obligations,

permits, or legal

constraints)?

(MGD)*

What is the

estimated potential

maximum daily

amount of water

that can be drawn

from each

goundwater well, 

given current

pumping and

equipment

constraints only

(e.g. system

components and

physical

constraints)? (MGD)

G1 1 2 1 2

G2 1 2 1 2

G3 1 2 1 2

G4 1 2 1 2

G5 1 2 1 2

* If not limited enter “no limit” here. Q10B Totals
Page 8 of 22

C. Purchased water source.

Purchased

water

intake

identifiers

Provide the names of the sellers for this

water

Is this a

seasonal

source?

(Circle 1

for yes and

2 for no)

Yes No

What was the

average daily

amount of water

drawn from each

purchased water

intake during the

reporting period in

Question 2A?

(MGD)

What is the

estimated

potential

maximum 

amount drawn

from each

purchased water

intake given water

availability

constraints only

(e.g. source

capacity

contractual

obligations,

permits, or legal

constraints)?

(MGD)*

What is the

estimated

potential

maximum 

amount drawn

from each

purchased water

intake, given

current pumping

and equipment

constraints only

(e.g. system

components and

physical

constraints)?

(MGD)

P1 1 2

P2 1 2

P3 1 2

P4 1 2

P5 1 2

Q10C Totals

Totals for all intakes Q10A-Q10C (MGD)

* If not limited enter “no limit” here.

11. Does your system provide treatment? (Circle one)

Yes .............................................. 1

No (go to Question 18) .............................. 2
Page 9 of 22

12. Provide the following information for each water treatment plant or other facility at this utility. Design Capacity

refers to the maximum amount the plant can produce in a single 24 hour period with all treatment trains operating

at capacity. Peak daily production refers to the maximum amount produced in a single day over the twelve month

reporting period in Question 2A. Please submit site plans and flow charts of each treatment facility in your

water system. 

Water treatment plant

identifiers

List all of the surface,

ground, and purchased

water intake identifiers

from Question 10 that

feed into each water

treatment plant or

other facility.

What was the average

daily production for

each water treatment

plant or other facility? 

(MGD)

What was the peak

daily production for

each water treatment

plant or other facility? 

(MGD)

What was the design

capacity for each water

treatment plant or

other facility?

 (MGD)

WTP1

WTP2

WTP3

WTP4

WTP5

Note: WTP refers to a treatment plant or any other facility that provides treatment.

13. Using the water treatment plant identifiers from Question 12, indicate which water treatment objectives apply to

each plant. (Circle 1 for Yes and 2 for No). 

Do you have this treatment objective in the following

water treatment plant?

 (use the plant number from Question 12)

WTP1 WTP2 WTP3 WTP4 WTP5

Yes No Yes No Yes No Yes No Yes No

Algae control ....................................... 1 2 1 2 1 2 1 2 1 2

Corrosion control .................................... 1 2 1 2 1 2 1 2 1 2

Disinfection ........................................ 1 2 1 2 1 2 1 2 1 2

Dechlorination ...................................... 1 2 1 2 1 2 1 2 1 2

Oxidation .......................................... 1 2 1 2 1 2 1 2 1 2

Iron removal ........................................ 1 2 1 2 1 2 1 2 1 2

Manganese removal .................................. 1 2 1 2 1 2 1 2 1 2

Fluoridation ........................................ 1 2 1 2 1 2 1 2 1 2

Taste/odor control ................................... 1 2 1 2 1 2 1 2 1 2

TOC removal ....................................... 1 2 1 2 1 2 1 2 1 2

Particulate/Turbidity Removal .......................... 1 2 1 2 1 2 1 2 1 2

Softening (hardness removal) ........................... 1 2 1 2 1 2 1 2 1 2

Recarbonation ...................................... 1 2 1 2 1 2 1 2 1 2

Organic contaminant removal (e.g., VOCs, pesticides) ....... 1 2 1 2 1 2 1 2 1 2

Inorganic contaminant removal (e.g., arsenic) .............. 1 2 1 2 1 2 1 2 1 2

Radionuclides contaminant removal ..................... 1 2 1 2 1 2 1 2 1 2

Other (specify) 1 2 1 2 1 2 1 2 1 2
Page 10 of 22

14 A. Using the Water Treatment plant identifiers from Question 12, characterize the treatment used and the

sequence of treatment for each plant by entering a number to identify the order in which each treatment

process occurs for each water treatment plant. (See example. If you have the option of more than one

treatment type for a single step – e.g., you can use either chlorine or chlorine dioxide for disinfection –

assign the same sequence number to each alternative). 

Water Treatment Plant Number (from

Question 12)

Treatment Category Example1 WTP1 WTP2 WTP3 WTP4 WTP5

Chlorination only

Raw water storage/Presedimentation basin

Predisinfection/oxidation prior to sedimentation

Chlorine 2

Chlorine dioxide

Chloramines

Ozone

Potassium permanganate 3

Other Predisinfection

Predisinfection/Oxidation prior to filtration

Chlorine

Chlorine dioxide

Chloramines

Ozone

Potassium permanganate

Other Predisinfection

Rapid mix

Coagulation/ Flocculation

Polymers

Settling/Sedimentation 4

Softening

Lime/soda ash

Recarbonation

Ion exchange

Filtration

Direct filtration

Micro strainer

Slow sand

Bag and Cartridge

Rapid sand

Green sand 5

Diatomaceous earth

Dual/Multi media

Pressure filtration

Other (specify)

Post-disinfection after filters

Chlorine 7

Chlorine dioxide

Chloramines

Ozone

UV

Other post disinfection

Clearwell
Water Treatment Plant Number (from

Question 12)

Treatment Category Example1 WTP1 WTP2 WTP3 WTP4 WTP5

Page 11 of 22

Membranes

Reverse osmosis

Micro filtration

Ultrafiltration

Nanofiltration

Corrosion Control

Miscellaneous

Ion exchange

Granular activated carbon

Activated Alumina

Aeration 1

Other (please specify) 6

1. This is an example of a green sand filter plant for treating ground water for Iron and Manganese removal. In this example

‘other ‘ is contact basin.

B. Using the Water Treatment plant identifiers from Question 12, indicate which filter backwash techniques

you use for each treatment plant that uses filtration. (Check all that apply). 

Water Treatment Plant Number (from Question 12)

Filter backwash Example WTP1 WTP2 WTP3 WTP4 WTP5

Air scouring

Surface wash x

Recycle filter backwash

Filter to waste x

Other filter backwash x

None
Page 12 of 22

[QUESTION 15 ASKED OF VERY LARGE SYSTEMS ONLY] 

15. Using the identifiers from questions 10 and 12, please list the intake or entry point identifier number and

concentration for each water quality parameter (contaminant) for the reporting period recorded in Question 2A.

If you conducted multiple tests of a source over the reporting period, report the average concentration. If you

did not test for a contaminant mark N/A; if you did not detect a contaminant mark ND. If you require additional

space for entry points/well identifiers please attach an additional sheet. 

A. Using the source identifiers from questions 10, please provide raw water concentration in units of parts per

million (ppm) for each compound: 

Intake

Identifier 

Raw Water Concentration (units- ppm, except Radon - pCi/L)

Arsenic Radon MTBE Atrazine Metolachlor Boron 2,4-D Simazine Glyphosat

e

Example 1: 

G-1/W-1

<0.002 N/A N/A N/A N/A N/A ND 0.001 0.01

Example 2: 

G-1/W-2

0.002 100 N/A 0.002 N/A N/A ND ND ND
Page 13 of 22

B. Using the treatment plant identifiers from question 12, please provide post-treatment concentration in units

of parts per million (ppm) for each compound:

Entry

Point

Identifier

Treated Water Concentration (units- ppm, except Radon - pCi/L)

Arsenic Radon MTBE Atrazine Metolachlor Boron 2,4-D Simazine Glyphosat

e

Example 1: 

WTP-1

<0.002 N/A N/A ND N/A N/A ND 0.001 0.01

Example 3:

WTP-2

0.002 ND N/A ND N/A N/A ND ND ND
Page 14 of 22

16 A. Using the water treatment facility identifiers from Question 12, indicate if the specified residuals

management practices are used and provide the requested information regarding potential discharge.

(Circle 1 for Yes and 2 for No).

Do you use the following residual management process in the

following water treatment plants?

 (use the water treatment plant numbers from Question 12)

Residual Management WTP1 WTP2 WTP3 WTP4 WTP5

Category Yes No Yes No Yes No Yes No Yes No

Mechanical dewatering ........................ 1 2 1 2 1 2 1 2 1 2

Non-mechanical dewatering .................... 1 2 1 2 1 2 1 2 1 2

Chemical precipitation ........................ 1 2 1 2 1 2 1 2 1 2

Land application ............................. 1 2 1 2 1 2 1 2 1 2

Nonhazardous waste landfill ................... 1 2 1 2 1 2 1 2 1 2

Deep well injection ........................... 1 2 1 2 1 2 1 2 1 2

Evaporation pond ............................ 1 2 1 2 1 2 1 2 1 2

French drain ................................ 1 2 1 2 1 2 1 2 1 2

Direct discharge to surface water ................ 1 2 1 2 1 2 1 2 1 2

If no, is direct discharge to surface water an option? 1 2 1 2 1 2 1 2 1 2

Septic system ............................... 1 2 1 2 1 2 1 2 1 2

If no, is discharge to a septic system an option? ... 1 2 1 2 1 2 1 2 1 2

Sanitary sewer .............................. 1 2 1 2 1 2 1 2 1 2

If no, is discharge to a sanitary sewer an option? ... 1 2 1 2 1 2 1 2 1 2

B. Please describe any current limitations on the use of direct discharge to surface water, septic systems, and

discharge to sanitary sewer for residuals management at any of the water treatment plants at this utility.
Page 15 of 22

17. Using the water treatment plant identifiers from Question 12, provide the following information regarding

operators and SCADA usage at each water treatment plant at this utility. (SCADA Supervisory Control and

Data Acquisition system is an automated system for monitoring, controlling, and /or transmitting information

on water treatment plant processes).

Water Treatment Plant 

(use the water treatment plant numbers from 

Question 12)

Operator Information WTP1 WTP2 WTP3 WTP4 WTP5

Yes No Yes No Yes No Yes No Yes No

1. Is there an operator on-site 24 hours per day seven days per

week? (Circle yes or no) ........................... 1 2 1 2 1 2 1 2 1 2

2. If the above answer is no, estimate the total number of hours

per week that an operator is on site ..................

3. Is there a SCADA in use for process monitoring? (Circle yes

or no) ......................................... 1 2 1 2 1 2 1 2 1 2

4. Is there a SCADA in use for process control? (Circle yes or

no) ........................................... 1 2 1 2 1 2 1 2 1 2

B. STORAGE AND DISTRIBUTION SYSTEM INFORMATION

18. Please indicate whether you have the following types of treated-water storage, and if so, the number of storage

facilities and their capacity, in millions of gallons. 

Yes No

If yes, what is the

total capacity of the

storage (in millions

of gallons)?

A. Do you have clearwell storage after treatment? ...................... 1 2

B. Do you have storage after treatment (and after clearwell, if any), but before

the distribution system with dedicated entry and exit points? ........... 1 2

C. Do you have storage after treatment (and after clearwell, if any), but before

the distribution system with a common inlet and outlet (i.e., rides the line) 1 2

D. Do you have storage within the distribution system with dedicated entry

and exit points? .............................................. 1 2

E. Do you have storage within the distribution system with a common inlet

and outlet (i.e., rides the line)? ................................... 1 2
Page 16 of 22

19 A. Estimate the length of the distribution mains pipe in your system, and length of pipe replaced in the last five

years. 

Pipe Diameter

Length of Pipe 

(In Miles)

Length of Pipe Replaced in

the Last 5 Years1

(In Miles)

Total Cost of Pipe Replaced in

the Last 5 Years1

(In Dollars)

Less than or equal to 

6"

Greater than 6" but

less than or equal to

10"

Greater than 10"

1.Ending on the date shown in your answer to Question 2A.

B. What percentage of the total length of pipe in the distribution system is less than 40 years old, between 40

and 80 years old, and more than 80 years old? (The percentages should total 100 percent.)

1. Less than 40 years old .............................. %

2. Between 40 and 80 years old ........................ %

3. More than 80 years old ............................. %

20. A. How many people and connections does your system currently serve year round? Please indicate the

number of connections and number of people served by your system for all customer types that apply. (If

you cannot distinguish among the different types of non-residential customers, enter the total for your

non-residential customers in line c.4.)

Customer Type Connections Number of

People

a. Sold to other public water suppliers

1. Treated water ................................

2. Untreated water ..............................

b. Residential ..........................................

c. Non-residential 

1. Commercial/industrial .........................

2. Agricultural .................................

3. Other (specify)

4. Subtotal, non-residential ........................
Page 17 of 22

[QUESTIONS 20 B. AND 20 C. ASKED OF SMALL, MEDIUM, LARGE SYSTEMS ONLY]

B. Does your system serve a residential population that changes on a seasonal basis (for example, is it a

winter or summer resort area)? (Circle one)

Yes .............................................. 1

No (Go to Question 21) .............................. 2 

C. If your system serves a population that changes on a seasonal basis, please indicate the highest seasonal

number of people (residential only), the highest number of residential connections and the number of

months each year during which the seasonal population is the highest. 

1. Highest seasonal population ..........................

2. Highest number of seasonal residential connections .......

3. Number of months when seasonal population is highest ....

21. Please enclose a map of your service area 

C. CROSS CONNECTION CONTROL

22. Does your system have a cross connection control (CCC) program? (Circle one)

Yes ............................................... 1

No (Go to Question 26) ............................... 2

Don’t Know (Go to Question 26) ....................... 3

23. Please indicated the type of program your system has. (Circle one)

Containment (A program that is designed to prevent backflow from reaching a publicly 

owned distribution system, but does not provide protection within the 

premises. This often is referred to as providing protection up to the meter.) ......... 1

Containment 

and isolation 

(A program that is designed to prevent backflow from reaching a publicly 

owned distribution system and provides protection within a customer's 

premises. This often is referred to as providing protection up to the tap.) ........... 2
Page 18 of 22

24. Please indicate which elements are included in the CCC program:

(Circle 1 for "yes" and 2 for "no")

Cross Connection Control 

Does your program

include this element?

Program Elements Yes No

a. Right of entry .................................. 1 2

b. Surveys/inspections to identify cross connections within

the system/facility ............................... 1 2

c. Policy specifying which service connections must be

equipped with backflow prevention device/assemblies . . 1 2

d. Enforcement authority to install devices/assemblies. .... 1 2

e. Enforcement authority to test assemblies ............. 1 2

f. Penalties for non-compliance 

with ordinance ................................. 1 2

g. Public education programs ........................ 1 2

h. Training/certification of testers 

and inspectors .................................. 1 2

25. What percentage of backflow prevention assemblies that are 

tested fail annually during inspection? 

(An assembly is a device that can be tested) ................ %
Page 19 of 22

Part II – Financial Characteristics

Reporting period: For Part II of the survey, please use the period indicated in Question 2(B) to report

“last year’s” financial data. 

Providing estimates: Please provide exact information from your system’s records. Otherwise, provide

your best estimate of financial information that is applicable to your drinking water system.

If your system is a joint drinking water/wastewater facility, please be careful to record only data that are

relevant to the drinking water part of the facility. If data for the drinking water part of the facility are not

kept separately, please provide your best estimate of the share that is attributed to drinking water. 

Rounding: Please record your dollar amounts to the nearest dollar. Do NOT record cents. 

26 A. During the last year [as defined in your response to Question 2(B)] what were your drinking water system’s

revenues from water sales for each of the following customer categories. 

(If zero, enter "0". Note: if you cannot distinguish among the different types of non-residential customers,

enter the total for your non-residential customers in line d.)

Water Sales Customer Categories Water Sales Revenues

1. Sold to other water suppliers

a. Treated water ...................................... $

b. Untreated water .................................... $

2. Residential ............................................ $

3. Non-residential

a. Commercial/industrial ............................... $

b. Agricultural ....................................... $

c. Other (please specify) $

d. Subtotal, nonresidential (a - c) ......................... $

4. Total water sales revenues (1-3) ............................ $
Page 20 of 22

B. Please indicate your water system’s revenues during the last year from other water-related revenue sources. 

(If zero, enter ‘0’)

Water-related Revenues

5. Connection fees ....................................... $

6. Development fees ...................................... $

7. General fund revenues (e.g., from municipalities) ............. $

8. Other water revenues not reported in the categories above 

(e.g., fines, penalties, other fees) 

(Please specify) $

9. Total water-related revenues ............................. $

C. Please indicate your total water system revenues from lines 4 and 9 above.

10. Total water system revenues (lines 4 + 9) ................ $

[QUESTION 27 ASKED OF SMALL, MEDIUM, AND LARGE SYSTEMS ONLY]

27. If your primary business is not water-related and you reported 

no revenues in Question 26 A or B, please indicate the revenues 

you receive from your primary, non-water related business, 

including rental income and the sale of other goods or services ........ $

Note: Questions 28 - 30 Refer to Residential Customers Only

28. What is the average annual bill for a residential customer? ............ $

29. Please identify your drinking water system’s billing structure for residential customers (circle all that apply). 

Billing

structure

(Circle all that

apply)

Metered charges

Uniform rates ..................................................................... 1

Declining block rate ................................................................ 2

Increasing block rate ................................................................ 3

Peak period rate (e.g., seasonal) ...................................................... 4

Unmetered charges

Separate flat fee for water ............................................................ 5

Combined flat fee for water and other services (e.g., rental fees, associate feeds, pad fees) ......... 6

Other billing methods (Please specify) 7
Page 21 of 22

30 A. Does your system use rates that may lower the cost of drinking water for low-income or fixed-income

households? (e.g., lifeline rates) (Circle one)? 

Yes ............................................... 1

No (Go to Question 31) ............................... 2

B. If your system uses rates that lower the cost of drinking water for low-income or fixed-income households,

please answer the following: 

1. How many households receive these rates? ............ (Number of households)

2. What is the highest annual income that qualifies for these

rates? . ........................................ (Dollars per year)

3. How much does it cost your system to provide these rate

reductions (i.e., what is the total dollar amount of the

reductions)? .................................... (Dollars per year)

31. Question 31 is intended to account for all of your drinking water expenses related to the revenues referred to in

question 26 A and B. 

A. Please enter the number of people employed by your drinking water system and your system’s total

compensation expenses (including direct compensation and fringe benefits) in the last year: If your system

is operated by or employs a contractor, enter the number of contract employees and total expenses of the

contractor on line 2.

Last year’s employment and compensation

1. Number of Employees

2. Total Expenses,

including fringe benefits

(in Dollars)

1. Employment and employee expenses ....... $

2. Contractor expenses .................... $

B. Please enter other routine operating expenses in the last year (in dollars) ...... $

C. Please enter the amount of debt service expenditures in the last year for 

borrowing to finance capital expenses (i.e., excluding expenditures for 

borrowing to finance operating expenses, in dollars) ...................... $

D. Please enter the amount of other expenses (excluding operating and debt 

service expenses reported in Parts A, B, and C, but including any debt 

service expenditures for borrowing to finance operating expenses) in the 

last year (in dollars) (Please specify) ..... $

E. Total expenses, Parts A through D. (in dollars) .......................... $
Page 22 of 22

32. A. If you have paid for major capital improvements, repairs, or expansion in the last five years ending on the

date reported in Question 2B, allocate those expenditures to the following categories. 

Type of Expense Total

1. Land ................................................ $

2. Water source .......................................... $

3. Distribution and transmission system ....................... $

4. Treatment ............................................ $

5. Storage .............................................. $

6 All other not included above ............................. $

7. Total capital expenses .................................. $

B. What percent of the total capital expenditures from Line 7 of Part A was for water quality improvement,

replacement or major repair, or system expansion.? (The percentages should total to 100 percent.)

1. Water quality improvements ....................................... %

2. Replacement or major repair ...................................... %

3. System expansion ............................................... %

C. How were the total expenses from Line 7 in Part A funded?

Source of funds

Percentage of

capital expenses

funded from

each source

(Should sum to

100%)

Average Interest

Rate

1. Current revenues ......................................... %

2. Grants from the Drinking Water State Revolving Fund ............ %

3. Other government grants (either Federal or State) ................ %

4 Borrowing from the Drinking Water State Revolving Fund ......... % %

5. Borrowing from other public sector sources (e.g., state or regional

authorities) .............................................. % %

6. Borrowing from private sector sources (e.g., banks or the bond market) % %

7. Other (please specify) % %
THIS PAGE INTENTIONALLY LEFT BLANK
Office of Water (4607M)

EPA 815-R-02-005B

December 2002

www.epa.gov/safewater

Printed on Recycled Paper