Work out peak water demand factor instantly with clear inputs, formula shown and shareable results.
Distribution networks are sized on peak hour flow, which is average demand multiplied by a maximum day factor of 1.3-1.8 and a peak hour factor of 1.5-3.0. Small communities show much sharper peaks; Harmon's formula, 1 + 14/(4 + sqrt(population in thousands)), captures that population-dependent damping.
Peak flows
Maximum day = average x max day factor; peak hour = average x max day factor x peak hour factor
Harmon formula
Peak factor = 1 + 14 / (4 + sqrt(population / 1000))
Source and treatment are sized on maximum day, distribution mains and service reservoirs on peak hour, and pumps often on maximum day with storage absorbing the hourly peak.
Fewer users means less statistical smoothing of individual demand. A village of 500 can see peak hour flows four or five times average, while a city of a million rarely exceeds twice.