It is a unit of measure used to evaluate the demand that a particular plumbing fixture, or group of fixtures, will put on the plumbing system. It is used in conjunction with other factors, and there are fixture units assigned for both water supply and drainage. The fixture unit rating takes into account the likely volume of flow, average duration of use, and expected frequency of use. Here’s how the Residential Edition of the Florida Building Code (FBC) and the International Residential Code (IRC) define them:

    A full bathroom, for example, is rated at 3.6 w.s.f.u. (water supply fixture units), while a clothes washer is given a 1.4. Only fixtures that dispense water have fixture unit ratings so, although fixture units are used to calculate the size pipe serving a water heater, the water heater itself is not assigned a fixture unit value.

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Here’s links to a collection of our other blog posts about PLUMBING:

• How can I protect my pipes to keep them from bursting during a hard winter freeze in North Florida?

• Why is there sand in the bottom of my toilet tank?  

• What causes a gurgling sound when a bathtub or sink drains? 

• Are drop-in toilet bowl cleaner tablets safe? 

• What can I add to my septic tank to help it work better?

• What are the code requirements for layout of drain piping under sinks? 

• Why is there mold inside my toilet tank?  

• What are the pros and cons of a wall-mounted toilet?

• Which plumbing fixtures require water shut off valves in a home? 

• How can I tell if a house is connected to a septic tank system or sewer?

• Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water? 

• Why is a backflow preventer required on lawn sprinkler systems? 

• How can I locate my septic tank? 

• What's that powdery crust on the pipe connections at the water heater? 

• How can I tell what type of plumbing pipe I have? 

  • What causes low water pressure in a house?

      Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.