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Hello. I'm looking for a formula or guidance on sizing a water storage tank that I'm purchasing for both domestic water use, and fire suppression. I've heard there is a formula based on the cubic feet of the building. Thanks for any help you can provide.

Alan

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Look in NFPA 13, 13D or 13R depending on the structure. All sprinkler systems must be designed by a design professional/ sprinkler engineer who calculate spacing, flow requirements and storage capacities for those systems "off the grid".
Adam, Thanks, I'll check those out.
(P.S. I'm not planning a sprinkler system. I just want a large water tank (5K or 10 K gal.) that can server as a source of water for a fire truck or my own personal pump/1.5 in hose).
Alan

Adam Miceli said:
Look in NFPA 13, 13D or 13R depending on the structure. All sprinkler systems must be designed by a design professional/ sprinkler engineer who calculate spacing, flow requirements and storage capacities for those systems "off the grid".
If your looking to have a static supply of water for the FD to use for a fire in your house, a good many of us use the National Fire Academy formula for determining our fire flow: Length X Width / 3 per floor plus 25% for close exposure buildings.

So a standard 2 story house 30x40 with a unattached garage:

30x40/3+ 400 gpm + 100 gpm for the garage+ 500 gallons per minute flowing. Of course that doesn't consider the overall quantity to extinguish. I think NFPA 1403 has a formula for determining static water on hand for fire attack training in acquired structures?
Adam,

Thanks for the guidance, it will be helpful in sizing my storage tank. I'm 15 min. from the closets fire station so I'm trying to accomplish three things. The first is to have water on hand for grass or structure fire containment, until the pros arrive. The second is to have water for them to replenish their tankers, if needed. The third is to have water for domestic use.

Thanks,
Alan
If you look at ISO requirements for water supply points, they require that a water supply point that is not connected to a main should be capable of providing a fire flow of 250 gpm for a minimum of 2 hours (120 minutes). In other words, a rated water supply point should have a year-round capacity of 30,000 gal (250 gpm x 120 minutes = 30,000 gal). This would apply to a pond, cistern, or tank. 250 gpm is a relatively low fire flow for a structure fire, but most buildings don't require a full two hours of non-stop water flow, either!

My fire district conducts operations using tanker shuttles, with key water source locations throughout the district. My observations, based on our last several years of operations, is that a typical residence that is fully involved upon arrival seldom takes more than 6,000-10,000 gal of water to extinguish. [Your mileage may vary! ;-) ] I'm sure that any fire department would appreciate a supply of water on scene, providing they can access that water. You might consider having a large, valved opening on your tank. Check with your local fire department to see what type of threads they use, hopefully National Standard Thread (NST), and what size of valve they would prefer to use to access the water. You might find that the local fire department would contribute to your project if you made your tank of water available for other emergencies in your area.

You may not be interested in supplying 30,000 gal of water by yourself, but it is a recognized amount based upon a reasonable set of assumptions. You can modify this design based upon your own set of assumptions and the input of your local fire department.

Jeff
Jeffery,

Thanks, some good advise. I plan a fire dept. hose connection and will find out what's suggested for my area.

Alan

Jeffery A. Hartle said:
If you look at ISO requirements for water supply points, they require that a water supply point that is not connected to a main should be capable of providing a fire flow of 250 gpm for a minimum of 2 hours (120 minutes). In other words, a rated water supply point should have a year-round capacity of 30,000 gal (250 gpm x 120 minutes = 30,000 gal). This would apply to a pond, cistern, or tank. 250 gpm is a relatively low fire flow for a structure fire, but most buildings don't require a full two hours of non-stop water flow, either!

My fire district conducts operations using tanker shuttles, with key water source locations throughout the district. My observations, based on our last several years of operations, is that a typical residence that is fully involved upon arrival seldom takes more than 6,000-10,000 gal of water to extinguish. [Your mileage may vary! ;-) ] I'm sure that any fire department would appreciate a supply of water on scene, providing they can access that water. You might consider having a large, valved opening on your tank. Check with your local fire department to see what type of threads they use, hopefully National Standard Thread (NST), and what size of valve they would prefer to use to access the water. You might find that the local fire department would contribute to your project if you made your tank of water available for other emergencies in your area.

You may not be interested in supplying 30,000 gal of water by yourself, but it is a recognized amount based upon a reasonable set of assumptions. You can modify this design based upon your own set of assumptions and the input of your local fire department.

Jeff

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