Water Storage Tanks Similar to Fuel Storage?

8/7/2026

I have been introduced to a project that involves six underground water storage tanks and an external pump house that will provide fire protection water to a fully sprinklered building.

We have been informed that the sprinkler contractor will be providing the building sprinkler system design, but not the underground storage tank portion of the project.

The firm I work for performs a significant amount of fueling and convenience store design work for gas station and convenience store clients, but I am curious whether these water storage tank options are similar in nature to underground fuel storage tanks and their associated pumping equipment?

Obviously, the medium is different (water versus fuel), but I am interested in understanding whether there are comparable design considerations, equipment types, or industry standards.

Any guidance, resources, or lessons learned would be greatly appreciated. Thank you.

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3 Comments

Mark Harris

8/7/2026 10:42:52 am

Here is good place to start: https://xerxes.com/fire-protection-water-tanks/

Assuming the pump house will be above grade the pump will need to be vertical.

Jack G

8/7/2026 10:44:00 am

First of all you must choose the type of underground tanks fiberglass and or steel.
The tank must be listed per NFPA 22.
Pressure test the tanks for leaks or cracks. 5 psi for 24 hours. ( while on the truck);
If fiberglass, and is used for a combination domestic/ fire water it must be an internally coated set of tanks. ( for domestic water);
The tanks must be set and secured , on its own foundations with saddles and pea gravel is used to fill in. This is to prevent buoyancy as the tanks empty, and use a buoyancy calculator. Pea gravel is filled in gradually as you fill the tanks with water.
The tanks must be manifolded together using flexible connectors for settlement. Each supply to the manifold must have an anti vortex plate. In the center run your underground combined piping to a cistern of at least 4 ft diameter. ( concrete pipes like drainage with joint gaskets and patched over with fiberglass. The cistern must have a sump 2 ft deeper than the bottom of the underground pipe.
The size of the tanks, manifold pipe and fire pump supply to the cistern must be sized for the hazard and minimal friction loss. And / or domestic water use if combo tanks.
The tanks shall have proper vents and maintenance hatches and covered with earth to prevent freezing. Diameter of tanks is important.
A factory built pump house with foundations can be used. A vertical pump with shaft and impellers , diesel engine should be used. A submersible jockey pump , electric should also be used.
From the pump house supply your building and or hydrants keeping in mind flexible connectors should be used on piping between foundations.
If combo tanks , an electric domestic pump is used with a BFP.
The domestic water pump must be wired to shut off when the fire pump activates.
Also a method to refill the tanks automatically must be installed. Usually done via shaft type screw in magnetic switches screwed into the top of the tank.
A separate panel ( I use ) to monitor the tanks should also be used. And placed in the pump house with signals to the fire alarm panel ( low water, high water , leak detection etc. review NFPA 22)
Lastly electric and fire alarm wiring to the tanks, pump house, building, is installed within the underground trench. I keep it 3 feet away and use burial tape on top of both.
I hope this helps. Sort of soup to nuts. My first tank job was 56 years ago. I love to do them and try to pick up stuff with each job.
Good luck.

anthony

8/11/2026 09:12:52 am

"We have been informed that the sprinkler contractor will be providing the building sprinkler system design, but not the underground storage tank portion of the project."

This is fairly typical for sprinkler contractors, They're typically not underground work experts. Lots of easy ways to lose money if you're not doing this work frequently.

As Jack says above NFPA 22 is the pace to start for detailed specifics.

For generalities to your situation there is less focus on keep fuel out of the ground and more focus on keep the volume of required water in the tank. There will be level gauges but those will probably be connected to an auto fill feature from domestic/city water or a well. You may need to prove a water trucking contract to fill the tanks upon testing or other uses and have a buffer. (depending on the AHJ- yes I've had to do this). You'll need to confirm if there are hydrants that come off this tank (see questions from earlier this week) and determine fire flow. Heating will be a concern compared to gasoline. Venting will be an issue as you suck water out of the tank air needs to get back in this is often over looked by sprinkler folks.

Water Storage Tanks Similar to Fuel Storage?

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