Work out water demand for population instantly with clear inputs, formula shown and shareable results.
Domestic demand is population times per capita consumption. Institutional, commercial and industrial demand is added as a share, and the whole is grossed up for unaccounted-for water — leakage, meter error and unbilled use — which commonly runs 15-30% in developing distribution networks.
Water demand
Domestic (m3/d) = population x per capita demand / 1000
Gross demand
Gross = domestic x (1 + non-domestic share) / (1 - unaccounted-for water)
Design standards commonly specify 135 litres per person per day for piped sewered communities and 70-100 where sewerage is absent. Metered actual consumption is a better basis where data exists.
It sizes every asset upstream of the leak. Reducing it from 30% to 15% cuts required source, treatment and pumping capacity by nearly 18%, usually far cheaper than building new capacity.