definition: A sewage is a mixture of water, nutrients and solids.
It can be either black or white, but is generally defined as water and other solid waste that have mixed together.
A sewage can contain raw sewage, sewage sludge, sewage produced from sewage treatment plants, and so on.
Wikipedia definition: Black water is sewage produced in a sewage treatment plant, but can also be treated with chlorine or other disinfectants.
It is produced by sewage treatment systems that operate on low-flow, low-temperature sewage.
This is typically the result of an unregulated waste stream or a poorly maintained sewage treatment facility.
Wikipedia article definition for black water: The sewage produced by a sewage treated plant or wastewater treatment facility that is either black (black) or white (white) water is either clean (water that does not contain any contaminants) or contaminated with harmful bacteria.
Wikipedia link definition for sewage: A mixture of sewage, nutrients, and solutes produced by an untreated sewage treatment or waste water system or an unventilated sewage treatment system.
Wikipedia example of black water, sewage, and wastewater: A local black water treatment plant was recently shut down after a chemical leak caused the system to shut down, and the city began using the same untreated sewage for black and white water treatment.