Domestic Water Demand Calculator
Static · formula-only · worked example computed when this page was built · no live data
The Domestic Water Demand Calculator finds peak water flow, tank size, and booster need from a building's water-supply fixture units. Example: for a 3-floor building (50 persons) with 10 flush-valve WCs, 8 lavatories, and 4 showers, an office occupancy, Water fixture units = 124 WSFU, Peak flow = 275.9 L/min, Storage tank = 1 m³ (per PSME Code | ASPE Vol.2 | PNS 65 | ASHRAE 2021 Ch.50).
How it works
Computed from your inputs per PSME Code | ASPE Vol.2 | PNS 65 | ASHRAE 2021 Ch.50. Anything the worked example does not state uses this calculator's standard default; the interactive version shows every input and lets you change it.
Worked example (Plumbing & Pumps)
Inputs: a 3-floor building (50 persons) with 10 flush-valve WCs, 8 lavatories, and 4 showers, an office occupancy.
| Result | Value |
|---|---|
| Water fixture units | 124 WSFU |
| Peak flow | 275.9 L/min |
| Storage tank | 1 m³ |
Computed by WorkHive's calculation engine when this page was built; standard: PSME Code | ASPE Vol.2 | PNS 65 | ASHRAE 2021 Ch.50.
How to use this calculator
- Read the worked example. It uses a 3-floor building (50 persons) with 10 flush-valve WCs, 8 lavatories, and 4 showers, an office occupancy and shows every number in the method.
- Follow the formula with your own figures: it returns Water fixture units, Peak flow, Storage tank, computed per PSME Code | Hunter's Curve.
- To compute interactively, open the Domestic Water Demand Calculator inside WorkHive's free Engineering Design suite (link below). It runs the same method with your inputs.
FAQ
What is a domestic water demand calculator fixture units?
The Domestic Water Demand Calculator is a free online tool that finds peak water flow, tank size, and booster need from a building's water-supply fixture units. It shows the formula and a fully worked example so you can check the method, not just the number.
How is it calculated?
The result is computed from your inputs following PSME Code | Hunter's Curve. The worked example on this page shows a real computation with real numbers.
Is the calculator free?
Yes. WorkHive is free: this worked example is open to everyone, and the interactive calculator runs inside the free Engineering Design suite after a free sign-up (your work is saved to your account). WorkHive is a free, offline-first maintenance platform built for Philippine industrial plants.
Run it on your own numbers
Open the interactive Domestic Water Demand Calculator in WorkHive. Free, and a free sign-up saves your calculations, BOMs and scope-of-works to your account.