Water Supply Demand Calculator
Demand from Fixture Units
Calculate peak demand from water supply fixture units
Formula
Total WSFU = sum of all fixture units | GPM from Hunter/WSFU curve | Meter size from peak GPM
Frequently Asked Questions
What are water supply fixture units?
WSFU is a measure of probable water demand. Each fixture type has a WSFU value based on its flow rate and typical usage pattern. The total is converted to GPM using a diversity curve.
Why is peak demand less than sum of all fixtures?
Not all fixtures operate simultaneously. The Hunter curve (diversity curve) accounts for the probability that only a fraction of fixtures are in use at any given time.
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