Fire Hydrant Flow Testing

WaterOne conducts fire flow tests for engineers, developers, and sprinkler design companies. Fire Hydrant Flow test data supplied by WaterOne is a snapshot of how the public water distribution system is reacting to the flow test at a specific date and time. Design criteria should include a margin of safety to account for potential distribution system fluctuations in pressure and flow rates. WaterOne monitors pressures throughout the year and calculates anticipated average static pressure range for each pressure zone. This information will appear at the bottom of the flow test results.

Hydrant Capacity Test (Single Hydrant Flow Test)

A single hydrant flow test measures the water flow capacity at the hydrant. This test is useful to determine the flow rate available from a hydrant for a fire emergency. This test also verifies the mechanical operation of the test hydrant, as well as the piping and valves serving the hydrant.Illustration of a Single Hydrant Flow Test

Single Hydrant Flow Test: In this procedure, a pressure gauge is attached to one of the outlets of the hydrant. The air is expelled from the hydrant. A pressure gauge reading is taken before the hydrant is flowed (static pressure) and while the hydrant is being flowed (residual pressure). The nozzle pressure (pitot pressure) reading is taken from the outlet being flowed. (Image courtesy of Hose Monster.)

Main Capacity Test (Two or more Hydrant Flow test)

A two (or more) hydrant flow test measures the water flow capacity of the underground main. This test is useful to determine availability of water for the design of fire sprinkler and domestic water systems.

Illustration of a Two Hydrant Flow Test

Two Hydrant Flow Test: In this procedure, a pressure gauge is attached to one of the outlets of the static/residual hydrant. The air is expelled from the hydrants. A pressure gauge reading is taken before the hydrant is flowed (static pressure). A second hydrant (test hydrant) is flowed. While the hydrant is being flowed, the pressure gauge reading is taken (residual pressure). The nozzle pressure (pitot pressure) reading is taken from the outlet being flowed on the test hydrant. (Image courtesy of Hose Monster.)

Recommended Practice for Water Flow Testing

According to the National Fire Protection Association (NFPA) guidance for fire flow tests, the residual hydrant is where the static pressure will be observed with the other hydrant closed, and the residual pressure will be observed with the other hydrants flowing. This hydrant should be chosen such that it will be located between the hydrant to be flowed and the nearby main that is considered the source of water.

Schematic for a suggested test layout for hydrants

Suggested Test Layout for Hydrants (NFPA 291 Figure 4.4.4)

Historic Flow Information

WaterOne can provide historic single hydrant flow and pressure information, if available, free-of-charge. This information can be requested by emailing fireflow@waterone.org. Please include address or nearest intersection, map of project location, elevation (if known), and hydrant numbers (if known) with your request.

New Flow Information

New hydrant flow testing can be scheduled for a fee. Tests cannot be scheduled until the request and payment has been received. Fire hydrant flow tests will typically be completed within 5 business days after the payment and form has been processed, subject to weather and crew availability.

To schedule a new hydrant flow test, fill out the application and payment information on our new online form. 

Payment via paper application and check will still be accepted until December 31, 2023. You can find these forms below and send the form in with payment to the address provided on the application. 

Fire Hydrant Flow Test Applications:

Please send a map of the project location to fireflow@waterone.org.

Data Disclaimer: Water distribution information is taken at a single point in time and is subject to significant variation. This information is provided to the requestor for evaluation purposes only, without warranty of any kind, including but not limited to any expressed or implied warranty arising by contract, statute, or law. In no event regardless of cause, shall WaterOne be liable for any direct, indirect, special, punitive, or consequential damages of any kind whether such damages arise under contract, tort, strict liability or in equity.