All of us generate waste water every day, from toilets, sinks, showers and vehicle washing. Industries also produce a lot of waste water.
This waste water needs to be treated before it can be returned to the environment; otherwise it can harm animals and plants and make water unfit for drinking. It is easier and more cost effective to stop pollutants reaching the water course than to try and remove them once they are in our rivers but even well-treated sewage may be rich in nutrients, which can cause algae to grow excessively under certain circumstances. This can starve other species of essential oxygen and stop other plants and animals from thriving. Dissolved metals and some chemicals not normally removed by treatment processes can be toxic to some animals or plants.
Sewage treatment works are under increasing pressure from population growth an increased frequency of floods and droughts.
18% of the reasons for failure in the Swale, Ure, Nidd and Upper Ouse, and 13% in the Wharfe and Lower Ouse are due to the effect of sewage discharged from waste water treatment works and discharges from industry.