Residential Sprinklers -Water Usage Report

A recent report from The Fire Protection Research Foundation finds that water used for firefighting in homes without fire sprinkler systems can be up to 1200% greater than the water discharged by a fire sprinkler system.

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Summary

Three aspects of water consumption related to fire sprinkler systems were studied:

1. the actual water discharged by responding fire services at home fires without fire sprinkler systems,

2. the expected water discharged by fire sprinkler systems during a fire, and

3. the potential reduction of water infrastructure demand for communities with homes protected by fire sprinkler systems.

Based on a survey of the reported water used by fire services at 35 one- and two-family home fires from eight select communities, an average of 3,524 gallons of water was discharged for firefighting at homes without fire sprinkler system protection.

The data shows a range of 100 to 41,000 gallons of water used per fire, which is primarily attributed to the fire condition upon the arrival of fire services. Approximately 10 times increase of water used per fire was reported when the fire extended beyond the room of origin, or when the degree of fire involvement increased from visible flame and smoke to a fully-involved fire.

To estimate the water discharged by a fire sprinkler system during a fire, hydraulic calculations were performed on 18 fire sprinkler system designs of detached single-family homes and their provided water supply information. The calculations show that the expected water flow discharged by a single sprinkler operation during a fire ranges from 22 to 38 gpm with an average of 28 gpm. All of the fire sprinkler designs contained a pressure buffer (design margin) resulting in a calculated discharge flow that is higher than the minimum required flow per NFPA 13D39.

The level of the design margin included in a fire sprinkler design may vary and is at the discretion of the system designer. Assuming up to 10 minutes of operation, water consumption by a fire sprinkler system during a fire is approximately 280 gallons. In comparison, the average water used for firefighting in homes without fire sprinkler systems can be up to 1200% greater than the water discharged by a fire sprinkler system.

These results are consistent with previous studies of water consumption during fires in homes with and without fire sprinkler systems. The results also correlate with the survey data for the water needed to control the fire based on stage of fire development (i.e. within the room of origin), compared to the water used during the suppression of a fully-involved fire (i.e. extending beyond the room of origin).

Fire sprinkler systems are designed to operate at the early stages of the fire, and have successfully controlled most fires prior to the arrival of fire services. Therefore, water used by fire services responding to fires in homes protected by fire sprinkler systems is expected to be significantly less than homes without fire sprinkler systems.

The NFFs for 17 selected single family homes were determined based on NFPA 1, IFC, and ISO methods. In general, at least a 47% reduction of the projected water infrastructure demand for fire flow is produced when a community is protected by fire sprinkler systems.