How many gallons per minute are equivalent to one fixture unit?

• A. 7.5
• B. 5.0
• C. 10.0
• D. 2.5

Answer: (A)

Fixture units provide a way to estimate water demand by converting diverse fixtures into a single flow measure. Each fixture type is assigned a fixture-unit value, and to size the water supply you sum these values and convert to gallons per minute using a fixed rate. That rate is seven and a half gallons per minute per fixture unit. So one fixture unit equals 7.5 gpm. In design practice, you multiply the total fixture-unit count by 7.5 to estimate the required flow for the service or piping. The other options don’t match this standard conversion, so 7.5 gpm per fixture unit is the correct value.