Include Hydrants in Fire Pump Total Design Flow?

4/23/2026

Does the fire hydrant flow rate need to be included in the total design flow rate?

Assuming a building is only equipped with a standpipe system and a private hydrant system, both supplied by a private fire pump, does the design flow rate of the fire pump still need to account for the fire hydrant flow rate?

In addition, in accordance with NFPA 14‑2024 10.5.3.5.1, when the local fire department can meet the water supply capacity requirements, is the supply main for the standpipe system still required to be arranged in a loop?

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4 Comments

Glenn Berger

4/23/2026 08:41:52 am

Lots of questions have been asked in today's topic -

1) Does the fire hydrant flow rate need to be included in the total design flow rate? - YES

2) If you have a standpipe only system -Depending on the rules that are applicable in the project's jurisdiction will determine the answer. NFPA 1 has a fire flow requirement that needs to be evaluated. At times the NFPA 1 requirement will be greater than your NFPA 14 flow rate requirement.

You do not need to add the NFPA 1 requirement to the NFPA 14 requirement. You do need to use the greater flow rate. Note - pressure ratings at these flow rates will also be different.

3) Loop arrangement - This section of the standard is somewhat confusing.

Anthony

4/23/2026 08:46:01 am

Standpipe calculations do not include an outside hose allowance, if that is your question.

Flow at the hydrant before the standpipe system should not be counted as it is like any other nozzle on the system. The assumption is that the 1000 GPM, 750 etc is more than sufficient than required.

10.5.3 ONLY applies to instances where your supply is from a tank or the fire department can't supply water to the highest part of your building? Have you engaged the fire department and have that information?

Jesse

4/23/2026 11:41:57 am

I deal with this a lot, specifically in sizing tanks and pumps.

Fire flow, automatic sprinkler demand, and stand pipe demand are all different things. We generally don't compound them and calculatet the in aggregate.

For example, I have one project I'm sizing a pump and tank for that will provide fire flow to the hydrants and the AS systeme in a buiding. The sprinkler design criteria is an FM required density of 0.30 / 4,000 with 500-gpm hose for a duration of 1 hour. The total demand is roughly 112,800 gallons at a pressure yet to be determined.

The fire flow requirement is 1,000 gpm for 2 hours for a total of 120,000 gallons.

The AS demand is higher and will drive the pump capacity. But the fire flow requirement will need more water volume, so this will drive the storage tank.

Thankfully I'm not combining them.

Jim

4/29/2026 07:44:45 am

Excellent answer.

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Include Hydrants in Fire Pump Total Design Flow?

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