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.