On average each of us generates between 135 and 180 litres of sewage each day.
Sewerage is the network of sewers, pipes and pumps that lie unseen beneath virtually every street and road. Sewers carry sewage from where it is produced to the sewage treatment works to be treated and cleaned.
Sewage treatment works remove things that could harm the environment, so that the water can be returned to a river or the sea. At all points along the way the water is continously tested and monitored to ensure the right amount of chemicals are being added and that it is clean enough to be returned to the environment.