TL;DR
A fixture unit is the plumbing code's dimensionless measure of the demand a fixture places on a piping system, with separate scales for water supply (WSFU) and drainage (DFU) — values calibrated so designers can sum diverse fixtures and size pipes from code tables. A bathroom group, for instance, totals about 6 WSFU on supply.
What it means
A fixture unit is the plumbing code's dimensionless measure of the demand a fixture places on a piping system, with separate scales for water supply (WSFU) and drainage (DFU) — values calibrated so designers can sum diverse fixtures and size pipes from code tables. A bathroom group, for instance, totals about 6 WSFU on supply. The system exists because fixtures rarely run simultaneously; sizing for fixture units rather than raw flow keeps pipe diameters realistic in homes and small buildings.
Where it sits in the glossary
Fixture unit is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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