Peak Runoff Calculator

Posted by Dinesh on

Use the simple wastewater calculator to calculate peak runoff. Sewers must handle storm water flows during, and after, rain storms, and snowand ice-melting events. The rational formula for peak storm-water runoff is Q = C * I * A.
(i). In heavily populated urban areas C ranges from 0.70 to 0.90.
(ii). Residential areas with gardens, shrubs, and extensive open land have C values ranging from 0.30 to 0.40.


Q = C × I × A

  • A = drainage area
  • C = coefficient of runoff of area
  • I = average rainfall rate
  • Q = peak runoff