Ground Water Rule Sample 

Collection and Transport: A Quick 

Reference Guide

Sampling Location

►	For both triggered source water monitoring and assessment source water monitoring, 

samples must be collected at the ground water source before treatment, unless 

another location is approved by the State.

►	GWSs should install a sample tap at each source to enable source water monitoring.

►	The diagram below represents an appropriate sampling location for source water 

monitoring.

Overview of the Rule

Title Ground Water Rule (GWR) 71 FR 65574, November 8, 2006, Vol. 71, No. 

216 

Correction 71 FR 67427, November 21, 2006, Vol. 71, No. 224

Purpose Reduce the risk of illness caused by microbial contamination in public 

ground water systems (GWSs).

General 

Description

The GWR establishes a risk-targeted approach to identify GWSs 

susceptible to fecal contamination and requires corrective action to correct 

significant deficiencies and address source water fecal contamination in all

public GWSs. 

Utilities 

Covered

The GWR applies to all public water systems (PWSs) that use ground 

water, including consecutive systems, except that it does not apply to 

PWSs that combine all of their ground water with surface water or with 

ground water under the direct influence of surface water prior to treatment.

GWR Situations Requiring Sample Collection and Transport

►	The GWR requires that systems that do not provide 4-log treatment of viruses for all 

their ground water sources collect at least one source water sample after detection of 

total coliform in a routine Total Coliform Rule (TCR) (40 CFR 141.21) sample. These 

triggered source samples must be collected from ground water sources in use at the 

time of the TC positive. Samples must be collected within 24 hours unless the State 

allows an extension and the State will specify how long the extension is. Samples must 

be analyzed for the presence of one of three fecal indicators, E. coli, enterococci, or 

coliphage. See Ground Water Rule Triggered and Representative Monitoring: A Quick 

Reference Guide (EPA 815-F-08-004) for more information.

►	If a fecal indicator is found to be present in a triggered source sample and the State 

does not require corrective action, the GWR requires systems to collect five additional

source water samples and analyze the samples for the presence of one of the three 

fecal indicators.

►	Assessment source water monitoring may be required by the State for systems 

with sources that may be at risk for fecal contamination. Systems must meet 

State requirements for the number of samples collected and the analyses (E. coli, 

enterococci, coliphage) conducted.
Sample Collection

Sample Containers

►	Samples should be collected in sterile, plastic or glass containers with a leak-proof lid. 

►	The GWR requires GWSs conducting source water monitoring to analyze at least a 100-mL sample volume.

 However, EPA recommends that the GWS collect and ship more than 100-mL of sample to ensure that a minimum 

of 100 mL is available for analysis (see below). 

►	The sample containers should be large enough to allow at least 1-inch of headspace to facilitate mixing of the sample 

by shaking prior to analysis. 

►	Sample volume and container size recommendations for samples of various types are provided below.

E. coli and 

Enterococci 

Samples

►	Sample volume: At least 120 mL of sample should be collected to ensure sufficient volume for

sample analysis is available in the event of spillage at the laboratory. 

►	Container Size: The capacity of sample containers should allow at least a 1-inch headspace to 

facilitate mixing of the sample by shaking prior to analysis.

Coliphage 

Samples

►	Sample volume: If Method 1601 is used for coliphage sample analyses, either 100-mL or 1-L sample 

volumes may be analyzed (Method 1602 only accommodates 100-mL volumes). 

 While the minimum sample volume requirement for the GWR is 100 mL, systems may wish to 

collect and analyze a 1-L sample volume to increase the sensitivity of the Method 1601 analysis. 

 For all coliphage analyses, the GWS should collect 2.5 times more of the sample than necessary 

(i.e., 250 mL for 100 mL samples and 2.5 L for 1 L samples) to allow for sample re-analysis, if 

necessary.*

►	Container size: The capacity of sample containers should allow at least a 1-inch headspace to 

facilitate mixing of the sample by shaking prior to analysis.

* Alternatively, samples for male-specific and somatic coliphage analyses can be collected in separate containers.

Collection Procedures

Gloves and 

hand washing

►	When collecting samples from a ground water source, individuals should wash their hands before 

collecting samples and if possible wear gloves (latex, etc.).

Records ►	All samples taken should be recorded in an on-site sample log book or on a sample collection 

form if it is to be sent to a laboratory for analysis. Sample log books and sample collection forms 

should contain the following information:

 Name of system (e.g., Public Water System Identification number)

 Sample site location

 Sample type (assessment, triggered)

 Sampler’s name

 Sample number

 Date of sample collection

 Time of sample collection

 Analysis requested

Water tap and 

service line

►	Water taps used for sampling should be free of aerators, bubblers, strainers, hose attachments, 

mixing type faucets, and purification devices. The flow of water out of the tap should be adjusted so

the water will not splash out when the sample is collected. The tap should be cleaned and flushed.

►	The service line should be cleared before sampling by maintaining a steady water flow for at least

two minutes (or until the water changes temperature).

Collecting 

samples

►	Using aseptic technique (i.e., sanitize tap, do not touch the inside of the sample container), the 

individual taking the sample should fill the sample containers, leaving at least 1-inch of headspace.

Cap and label 

the container

►	Immediately following sample collection, the sampler should tighten the sample container lid.

►	The system name, sampler’s name, sample number, sample type, date and time of sample collection, 

sample location, and analysis requested should be recorded on the sample container.

►	IMPORTANT: If the sample will not be shipped off-site for analysis immediately, the sample should be 

placed upright in a refrigerator to maintain the sample at a temperature of < 8°C prior to shipment. If 

a refrigerator is unavailable, the sample should be insulated in some other manner to keep it cool.
Sample Collection

Sample Containers

Packaging ►	If the samples will be analyzed at a laboratory that is off-site, the water system should contact the 

laboratory as soon as possible (preferably prior to sampling) so that the laboratory can be prepared 

with the appropriate media.

►	As soon as the sample has been collected, labeled and capped, the sample should be packaged in a 

shipping cooler or foam box that is used exclusively for this purpose.

 The cooler should be double lined with plastic (i.e., with trash bags) and contain ice (wet ice in 

ziplock bags, gel packs, or blue ice). The GWR recommends keeping samples below 10°C.

►	The signed and dated sample collection form should be included with the sample.

►	The lid of the cooler should be securely sealed and the joints of the container should be sealed with

duct tape.

►	If the package is being shipped, a copy of the airbill or shipping record should be kept by the ground 

water system.

►	Packages should be sent priority overnight so that the arrangements for transport and shipping-time 

from collection to analysis does not exceed 30 hours as required by the GWR.

Chain-ofCustody►	Sample collectors and laboratories should follow applicable State regulations pertaining to chain-ofcustody procedures, since it is necessary to have an accurate written record to trace the possession 

and handling of samples from collection through reporting.

 This procedure includes:

• Field records of sample collection (sample collection form), 

• Label or standardized tag on the sample container(s),

• Package sent to lab with chain-of-custody record form, pertinent field records, and analysis

request form.

 The procedure used by the water system and the laboratory should be documented.

 Every person who takes custody of the sample should fill in the appropriate section of the chainof-custody record.

 See EPA’s Manual for the Certification of Laboratories Analyzing Drinking Water: Criteria and 

Procedures Quality Assurance (Fifth Edition) for more information.

Office of Water (4606) EPA 815-F-08-007 www.epa.gov/safewater July 2008