Water Supply vs. Fixture Water Requirements
Supply requirements for common fixtures.
Each fixture in a water supply system represents a certain demand of water. Supply requirement for common fixtures:
|Fixture||Flow rate||Minimum Supply Pressure|
|Dish washing machine||4||15||8||55|
|Drinking fountain jet||0.75||3||8||55|
|Hose bib or sillcock, 1/2"||5||19||8||55|
|Laundry faucet 1/2"||5||19||8||55|
|Lavatory faucet, ordinary||2||7.5||8||55|
|Lavatory faucet, self closing||2.5||10||8||55|
|Shower, temperature controlled||3||10||20||138|
|Sink faucet 3/8", 1/2"||4.5||17||8||55|
|Sink faucet 3/4"||6||23||8||55|
|Urinal flush valve||15||56||15||110|
|Water closet with flush valve||35||132||25||170|
|Water closet with gravity tank||2.5||10||8||55|
|Water closet with close coupled tank, ballcock||3||11||8||55|
Adding up the numbers to cover all fixtures in a system would give the total demand if all fixtures were used at the same time. This is almost never realistic for a supply system. Reasonable estimates must be made based on simultaneously demand from the fixtures.
Example - Required Water Supply
For a water supply system the summarized theoretical water flow for all fixtures is 10 l/s. The largest fixture in the system requires 0.4 l/s.
Based on the diagram above the expected total water flow in the system will be aprox. 1.1 l/s.