Install Fire Pump Only for Dry Systems?

6/24/2026

We currently have a structure being protected by four systems, two wet systems and two dry systems that protect a large attic area. It was recently discovered that the water supply is no longer sufficient to provide the dry systems with the water needed.

Would it be permitted to install a fire pump for only the dry systems?

The pump would be installed between the risers for the wet systems and the risers for the dry systems.

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11 Comments

Dan Wilder

6/24/2026 08:01:17 am

Technically yes, this would be allowed.....

But why restrict half the building on an already declining water supply just to potentially have to add it back in the future? This seems like more work to separate the two than to just have them all fed from the fire pump to start.

Is there a GPM issue where you'll need a larger pump capacity to make the wet work (the dry systems just need more pressure but less GPM) and you're being limited by an underground supply line size?

6/24/2026 08:14:47 am

The FDC arrangement for this would be challenging, and likely not possible.
an FDC cannot be on the suction side of the pump, and would have to supply all of the systems somehow.

Chad

6/24/2026 09:01:44 am

You will need to get AHJ approval for the FDC arrangement. Not a good plan overall, IMO

6/24/2026 09:12:14 am

My concern would be the possibility of drawing air into the pump from the FDC since the pump suction can pull the check open.

anthony

6/24/2026 08:56:54 am

Totally allowable defiantly shouldn't. There are plenty of buildings with bifurcated pump/no pump systems. ITs a headache for all involved so my strong suggestion is do not do it.

Michael Fertal

6/24/2026 09:56:24 am

Feasible, yes. Recommended, absolutely not! Dan W hit it right on. If the water supply is sliding now. Chances are it's going to continue sliding. Make the upgrade once.

Jose Figueroa

6/24/2026 10:13:56 am

No! Install a fire pump for the entire system, both wet and dry. Ensure the systems are balanced. This may lower costs and provide additional reliability. Who decided that the dry system isn't adequate? I wish the question had been addressed through hydraulic calculations.

Glenn Berger

6/24/2026 10:14:39 am

Permitted - yes

The location of the riser is problematic as others have indicated.

In addition, the fire pump may need to be located in a fire rated room.

Pete H

6/24/2026 02:20:45 pm

I agree with the consensus.

You can do it.

It's allowed by code.

But don't. It's a bad idea. Put the pump before all the risers at the header. It covers the wet parts of the building in case they increase hazard/storage. It's going to keep the FDC easy. It'll prepare for the water supply to continually degrade.

Jack G

6/26/2026 12:06:50 pm

Why would you? It would benefit the buildings fire systems to put it before the risers. Fdc s would be less complicated. Inspections too.
Diesel or electric? While diesels cost a lot so do electric services for fire pumps.
If electric, maybe a 400 @ 70 psi boost if city will support it. Good fo a well / broad flow for up to 600 gpm.

Jack G

6/26/2026 12:13:47 pm

That would be an optimal electric pump.
Diesel go with 500 gpm.

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Install Fire Pump Only for Dry Systems?

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