wastewater generated from domestic greywater and blackwater

Sewage or domestic wastewater is the liquid waste produced by people when using the toilet, having a bath or shower or washing clothes and dishes. In some places, it also includes rain-water falling on houses and roads. It can also have liquid waste from factories in it. It flows in pipes called sewers to be cleaned up at a sewage treatment works.

Sewage is mostly water but it also has many microbes some of which can be harmful. It can have many chemicals in it which can also cause harm to animals and humans. Most sewage in poor counties is not treated and may spread disease. A problem that occurs sometimes is a sewage spill which can be damaging to health and wildlife. [1]


Pumping station lifting sewage to the treatment plant in Bujumbura, Burundi
Greywater (a component of sewage) in a settling tank

The temperature of sewage tends to be slightly higher than in drinking water but it is more stable than the ambient temperature. The color of fresh sewage is slightly grey, whereas older sewage (also called "septic sewage") is dark grey or black. The odor of fresh sewage is "oily" and unpleasant. Older sewage has an unpleasant foul odor due to hydrogen sulfide gas and other decomposition by-products. Sewage can have high turbidity from suspended solids. [2][3]


  1. Matthews, Chris (3 August 2023). "'Absolutely sinking raw sewage' pouring into sea as people swim in poo". BristolLive.
  2. Wastewater engineering : treatment and reuse. George Tchobanoglous, Franklin L. Burton, H. David Stensel, Metcalf & Eddy (4th ed.). Boston: McGraw-Hill. 2003. ISBN 0-07-041878-0. OCLC 48053912.{{cite book}}: CS1 maint: others (link)
  3. Henze, M.; van Loosdrecht, M. C. M.; Ekama, G.A.; Brdjanovic, D. (2008). Biological Wastewater Treatment: Principles, Modelling and Design. IWA Publishing. doi:10.2166/9781780401867. ISBN 978-1-78040-186-7. S2CID 108595515. Spanish and Arabic versions available free online