Distribution Systems:

A Best Practices Guide

Introduction

Purpose This Guide discusses the importance of maintaining your distribution system.

Target

Audience

This Guide is intended for owners and operators of all public water systems

serving fewer than 10,000 persons.

Distribution Systems

Distribution Systems usually consist of:

 Piping and fittings  Pumps and pump stations  Meters

 Storage tanks  Backflow prevention devices  Hydrants and valves

Importance of Maintaining Your Distribution System

A properly maintained distribution system is important for ensuring that you can: provide high

quality water to your customers, continue operating in the event of an emergency, help

minimize property damage as a result of responding to an emergency, and help prevent

contamination events. A properly maintained distribution system can also extend equipment

life-cycles and minimize problems related to minor or major equipment failures.

Distribution System Routine and Preventative Maintenance Tasks

The following table provides suggested frequencies of routine and preventative maintenance

tasks for systems under normal operation. However, any time a system experiences water

quality issues, the appropriate tasks should be performed as frequently as needed. Contact

your state for more information.

Task Benefits Suggested Frequency

Valve exercising

 Improves reliability.

Annually.

 Familiarizes crews with valve

location.

 Identifies inoperable valves.

 Locates obstructed valve boxes.

 Ensures isolation of distribution

system sections when necessary.

Flushing pipelines

 Removes aged water from the

pipeline. Annually for all piping.

More often in areas with

water quality issues

(e.g., dead ends).

 Reduces buildup of biofilms and

sediments.

 Restores disinfectant residual.

Storage tank

inspections

 Detects vandalism.

Daily or weekly for

vandalism. Annually for

other items.

 Identifies defects.

 Ensures that access hatches are

locked.

 Ensures that vents, overflows, and

drains are screened.
Office of Water September 2006 EPA 816-F-06-038

Distribution System Routine and Preventative Maintenance Tasks

(continued)

Task Benefits SuggestedFrequency

Storage tank

maintenance

 Improves protection against

sources of contamination. Every 3 years for

cleaning. Painting and

repairs as dictated by

inspection.  Extends the useful life of the

equipment.

Routine water quality

monitoring (e.g., pH,

temperature)

 Provides information on potential

contamination of raw and finished

water. Will vary depending on

water quality and state

regulations.

 Helps determine effectiveness of

treatment.

 Helps assure the compatibility of

the water with the materials.

Inspecting and flushing

hydrants and valves

 Ensures that hydrants and valves

are operable and that no water

losses occur. Once or twice per year.

 Ensures that hydrants and valves

are not susceptible to tampering.

Maintaining operating

pressure range of

distribution system

 Reduces the risk of backflow

contamination.

Continuously.

 Helps your system provide better

service to customers.

 Reduces damage to infrastructure

due to excess pressure.

 Provides adequate fire flow.

Tracking unaccounted

for water

 Can reduce pumping and treatment

costs. Daily at the source.

Monthly or during

routine meter reading at

customer connections.  Helps identify leaks, breaks, stolen

water, and inaccurate meters.

Testing for presence of

excess biofilms

 Indicates a presence of inadequate

chlorine residual, possible high

disinfection byproduct levels, and

water stagnation.

Monthly in conjunction

with Total Coliform

sampling.

Monitoring corrosion  Identifies the need to modify

treatment or conduct flushing. Annually.

Checking for normal

wear (such as in

mechanical parts found

in pumps and control

valves)

 Can extend the useful life of

i e nfrastructure components. According to th

manufacturer's  y recommendations. Helps avoid unnecessar

replacement or operational costs.

For additional information:

Call the Safe Drinking Water Hotline at 1-800-426-4791, visit the EPA Web site at

www.epa.gov/safewater/smallsys.html, or contact your State drinking water representative.