Residential & Commercial Firewater Tank Sizing for Fire Suppression

Fire Water Tank Sizing for Fire Suppression

An adequate public water supply necessary for fire suppression is not always available, and in such cases a firewater tank can be used to aid in the suppression of fires which break out in either a residential or commercial setting. The tank sizing for such a firewater tank is important, because if it cannot meet the needs of fire suppression, the fire will not be contained, and it is likely that one or more buildings will be severely damaged as a result. Commercial firewater tanks in the Bay Area, as in other sections of the country, are generally sized according to a specific calculation which ensures there is sufficient water and water pressure to do the job.

The National Fire Academy formula 

This calculation has proven to be quite effective, provided that less than 50% of a building is involved with flames. The actual formula is as follows:

Needed fire flow = [(length x width) ÷ 3] x percent of involvement

As an example, a building which is 30′ x 30′ in length and width, and is 25% involved with flame, would have a needed fire flow of 900 square feet, divided by 3, which gives 300. Then this figure would be multiplied by the percentage of involvement, which is .25, to come up with a final answer of 75 gallons per minute. Given this fire flow requirement, a single hand line pumped at the right pressure should easily be able to produce the needed flow in gallons per minute.

Other considerations 

Any tank used for fire suppression must be outfitted with a device which ensures that the tank has adequate water supply for the duration necessary, as determined by the Fire Department. The supply outlet must be at least 4″ in diameter from the tank’s base to the point where the Fire Department would connect to it.

The location of the Fire Department outlet will be determined after reviewing a plot plan submitted to the department, but will always be no further away than 150′ and no closer than 50′ to the building in question. All tank supply lines must be constructed of an alloy or other material suitable for above-ground usage, and the water tank itself must be constructed of materials approved by the Fire Department.

Bay Area Commercial Fire Water Tanks

If you already have a fire water tank installed at your residence or near your commercial building, it may be worth your while to invest in a commercial firewater tank liner, so as to ensure that no leakage develops, and your tank is always filled with an adequate water supply. It may also stave off the need for firewater tank repairs, since the liner will act as a second line of defense against leaks and other mishaps. You can purchase fiber-reinforced plastic tanks that will ensure longevity in the life of your firewater tank, and keep you prepared for the possibility of a fire breaking out at your establishment.