Top diagram shows sewage and stormwater entering same system, with significant sewage released to environment. Bottom image has separated systems and discharges less pollution in heavy rains.

In a combined sewer system (top image), sewage and stormwater enter same system. Heavy rains result in significant amounts of sewage being released to environment. Separated sewer and stormwater systems (bottom image) handle each type of water separately, and discharge less pollution after heavy rains than combined systems do.

Public domain image by Fiona Martin, for NOAA Climate.gov.

Last modified: 
10 February 2022 - 1:29pm