Work out water use intensity instantly with clear inputs, formula shown and shareable results.
Water use intensity can be normalised by area or by occupancy, and for an office the per-occupant figure is the more diagnostic: most consumption is sanitary and therefore tracks people, not floor plate. Fifty litres per person per working day is efficient, over eighty suggests leaks or inefficient fittings.
Per occupant
Litres per person per day = annual kL x 1000 / (occupants x working days)
Per area
kL/m²/year = annual kL / area in m²
Litres per person per day = annual kL x 1000 / (occupants x working days). Water use intensity can be normalised by area or by occupancy, and for an office the per-occupant figure is the more diagnostic: most consumption is sanitary and therefore tracks people, not floor plate.
Evaporative cooling can double total consumption and it tracks weather, not occupancy. It should be sub-metered and reported separately from domestic use.
This calculator takes 3 inputs: Annual water consumption, Gross floor area, Occupants. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.