vvEPA

United States
Environmental Protection
Agency

Hydrant Sampler Procedure

Office of Water (MS-140)

EPA 815-B-23-012

December 2023


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Hydrant Sampler Procedure

Introduction

The hydrant sampler was developed to enable system operators to sample water quality from a
desired area of the distribution system, without accessing a residential or commercial tap.
Additionally, this approach can also allow system operators to quickly assess water quality in the
distribution system in the proximity of a routine compliance sample location. Dry barrel hydrants
are the most common type of hydrant. They are designed to be operated with their valves fully
open. The hydrant sampler referred to in this procedure was designed to allow the hydrant valve
to be fully open while collecting samples in a controlled, safe manner.

Hydrant Sampling Procedure

1.	Determine the time needed to flush the hydrant lead and riser (CFT) using the procedure
starting on the page 6.

2.	Ask the water system operator for the approximate pressure at the sample location. If
the pressure is > 125 psi at the sample location, install a pressure reducing valve (PRV)
adapter. See Figure 1.

3.	Have the system operator remove the hydrant outlet cap (Figure 2) and connect the
sampler to the hydrant, confirming the gave valve is closed (See Figure 3 for
identification of hydrant sampler parts and Figure 4 for hydrant sampler installation).

4.	Close the gate valve on the sampler (turn the valve clockwise).

5.	Have the system operator slowly open the hydrant until it is fully open.

6.	If the PRV Adapter is not being used (i.e., the system pressure is < 125 psi), record the
pressure reading from pressure gauge when both the sample and flush valves are closed.

7.	Open the gate valve (turn the valve counterclockwise) on the sampler and start the
timer. Note that the flow control valve restricts the hydrant flow to a constant rate of 20
gallons per minute (gpm). Allow the sampler to flush for the CFT, as shown in Figure 5.

8.	After flushing for the CFT collect the sample, following the steps below:

•	Close the sampler gate valve and remove the discharge hose,

•	Open the gate valve to achieve a flow rate suitable for sample collection,

•	Close the gate valve between samples (if applicable) and when sampling is complete.

9.	When sampling is complete, have the system operator

•	Slowly close the hydrant,

•	Slowly open the gate valve to release any remaining water pressure and confirm that
the hydrant is closed,

•	Remove the sampler from the hydrant.

Page 2 of 8


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Hydrant Sampler Procedure

Removing hydrant fitting

Figure 1. Removing hydrant fitting and attaching PRV adapter

Figure 2. Dry barrel hydrant

Page 3 of 8


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Hydrant Sampler Procedure

Figure 3. Hydrant sampler parts identification, without pressure reducing valve

Figure 4. Install hydrant sampler on hydrant

Page 4 of 8


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Hydrant Sampler Procedure

Figure 5. Flushing the hydrant

by swinging

Figure 6. Removing discharge hose for sample collection

Page 5 of 8


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Hydrant Sampler Procedure

Determining the Hydrant Flush Time

The use of the hydrant flushing improves the likelihood that the sample will be obtained from
water main. Note that:

•	Flushing for an insufficient amount of time may result in obtaining a water sample from
the hydrant service line.

•	Excessive over flushing may obtain a water sample from another part of the distribution
system further away from the intended sample location, especially in smaller diameter
distribution mains.

Thus, the user should identify the calculated flush time (CFT) needed for at that location
(particularly if this will be a routine sample location for the water system); however, field
experience has shown that flushing the hydrant sampler for 3 minutes will generally be
sufficient (e.g., for pipe diameters of 6 inches and a pipe length of 30 feet or less).

The CFT is determined using the following steps:

1.	Estimate the total length and diameter of the piping (lead line) between the main and
the hydrant (see Figure 7). Utilize operator's knowledge of system, a system/site map,
and design standards as needed.

Vertical length/diameter:

¦	The diameter of the hydrant riser diameter is typically 6 inches and assume that the
hydrant riser is 6 feet long based on design standards, unless indicated differently.

Horizontal length/diameter:

¦	The diameter of the hydrant lead is typically 6 inches, unless indicated differently.

¦	Measure or estimate the length of pipe between main and hydrant base. If the
location of the main is unknown, measure the horizontal distance between the
auxiliary valve to the hydrant and add one foot to account for distance from the main
to the auxiliary valve.

2.	Determine the necessary flush time from Table 1 based on the vertical and horizontal
pipe lengths and diameters, rounding up to the nearest length. Assume a 20 gpm flow
rate due to the flow control valve on hydrant sampler.

Page 6 of 8


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Hydrant Sampler Procedure

$

Ground Level

Auxiliary Valve

f)

Main

¦•nor

k	 Hydrant L

Figure 7. Typical Hydrant Installation

Line Length (feet)

4" ID

6" ID

9

00

5

0.5

0.5

1.0

10

0.5

1.0

1.5

15

0.5

1.5

3.0

20

1.0

1.5

3.0

25

1.0

2.0

3.5

30

1.0

2.5

4.0

35

1.5

3.0

5.0

40

1.5

3.0

5.5

45

1.5

3.5

5.5

50

2.0

4.0

6.5

60

2.0

4.5

8.0

70

2.5

5.5

9.5

80

3.0

6.0

10.5

90

3.0

7.0

12.0

100

3.5

7.5

13.5

Table 1. Minimum CFTs (minutes) at 20 gpm for Various Line Sizes (inner diameter, ID, in inches).

Page 7 of 8

Hydrant
Riser
Distance


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Hydrant Sampler Procedure

Note: Depending on the type of pipe material and degree of corrosion inside the pipe, the inner diameter will vary.
These diameters are meant to be approximations.

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