All of us generate waste water every day, from toilets, sinks, bathrooms, kitchen appliances and vehicle washing. Industry also produces a lot of wastewater. In most of the UK, our waste water gets combined with rain water from our homes, roofs and roads and it is all sent together to be treated at a sewage treatment works before the final treated effluent is discharged back to the environment.

Along the way to the treatment works, there are storm overflows on the sewer network which act as emergency release valves during times of heavy rainfall, discharging sewage mixed with rainfall to rivers, in order to stop the network backing up and flooding people’s homes. This approach has served us well in the past however this is no longer acceptable and the new Environment Act means that water companies have stringent targets to significantly reduce the number of times storm overflows operate. You can view a map of where storm overflows have discharged to rivers or the sea here.

You should also assume that anything you flush might end up in the river, so put a waste bin in your bathroom and only flush the three P’s down the toilet (pee, poo and paper) and be careful not to rinse fats, oils and grease down the sink as these can all congeal causing “fatbergs” which block the sewer.

This wastewater 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. When this happens it can  starve other species of essential oxygen and stop plants and animals from thriving. Dissolved metals and some chemicals not normally removed by treatment processes can be toxic to animals and plants.

Sewage treatment works are under increasing pressure from population growth and increased frequency of floods and droughts. 18% of the reasons for poor/bad ecological status 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 wastewater treatment works and discharges from industry.