Sewage

Sewage is the liquid waste produced by people when using the toilet, having a bath or shower or washing clothes and dishes. In some places, sewage also includes rain which has fallen on buildings and roads. It can also have liquid waste from factories in it. Sewage often flows in pipes called sewers. In more developed countries, this water might then be "cleaned up" at a sewage treatment facility; in others, it decays and rots, and can smell quite foul (both from the matter within it, such as faeces, urine, decaying foods, and so on, as well as from the microbes usually also present in the wastewater).

Sewage is generally high in water content but high in particulates; it also has many microbes, some of which can be harmful. Sewage can have many chemicals in it also, which can also cause harm to animals and people. Most sewage in poorer counties is not treated and may spread disease. Sewage spills often damage the health of wildlife, and sometimes also people.

Appearance

Pumping station lifting sewage to the treatment plant in Bujumbura, Burundi

Greywater (a component of sewage) in a settling tank

The color of fresh sewage is typically slightly grey, whereas older (this is called "septic sewage") or less hydrated sewage — for instance, in areas with low levels of running water — 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 levels of cloudiness from suspended solids.