In rural and suburban areas that don’t have a municipal water supply or where the available water supply can be affected by cyclical drought or freezing temperatures, NFPA 1142, Standard on Water Supplies for Suburban and Rural Firefighting, can be used to determine the minimum amount of water needed for structural firefighting.

As one way to minimize the amount of water needed, designers might turn to subsection 4.4.1 of the 2022 edition of NFPA 1142, which permits the authority having jurisdiction (AHJ) to reduce the water supply when the structure is protected by an automatic sprinkler system that fully meets the requirements of NFPA 13, Standard for the Installation of Sprinkler Systems; NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes; or NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies. (Stay tuned for a blog coming out in March 2024 on the differences between NFPA 13, 13D, and 13R.)

The Benefits of Sprinkler Systems

According to an NFPA^® Research report published in October 2021, “U.S. Experience with Sprinklers,” fire spread was confined to the object or room of origin in 95 percent of reported structure fires in which sprinkler systems were present and in only 71 percent of reported fires in properties with no automatic extinguishing system. From 2015 to 2019, sprinklers operated in 92 percent of fires considered large enough to activate them, and they were effective at controlling the fire in 96 percent of the incidents in which they operated. Overall, this means that sprinkler systems operated and were effective in 88 percent of the fires considered large enough to activate them.

In addition to being highly effective at controlling fires, automatic sprinkler systems have proven to be efficient in their use of available water. A single sprinkler typically discharges at 26 to 60 gpm (100 to 230 L/min), depending on the system pressure. According to the NFPA Research report, only one sprinkler operated in 77 percent of the structure fires where sprinklers operated, and five or fewer sprinklers operated in 97 percent of cases.

Considering this history, it is logical to conclude that automatic sprinkler systems should lessen the fire suppression burden and water supply needs of the fire department when responding to a fire involving a structure protected by an automatic sprinkler system.