Free Sewage Flow Calculator

Estimate the wastewater flow rate from a community based on water consumption and a return factor.

m^3/day
%

Average Sewage Flow

1,600 m^3/day

Peak Sewage Flow4,400 m^3/day
Peak Flow Rate50.9 L/s

Average Sewage Flow vs Average Water Demand

Sewage Flow Estimation

Wastewater flow is derived from water consumption, reduced by a return factor.

Formulas

Average sewage = Water demand x Return factor

Peak sewage = Average x Peak factor x (1 + Infiltration)

The return factor (0.7-0.9) accounts for water consumed (irrigation, evaporation) that does not reach the sewer. The peak factor accounts for diurnal variation, and infiltration accounts for groundwater entering through pipe joints.

Example Calculation

2000 m^3/day water demand, 0.8 return factor, 2.5 peak factor, 10% infiltration.

  1. 01Average sewage = 2000 x 0.8 = 1600 m^3/day
  2. 02Peak sewage = 1600 x 2.5 x 1.10 = 4400 m^3/day
  3. 03Peak flow rate = 4400 / 86.4 = 50.9 L/s

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