Storm overflows are mainly rainwater
A regular defence of the use of storm overflows is that they are a neccessary safety valve. They are not a serious risk to health because the combination of waste and rain water creates a dilute mix.
Storm overflows are used in combined sewer systems so are a mix of wastewater and rainwater. Their purpose is to provide a ‘release valve’ that reduces the risk of overloaded sewers causing flooding during heavy rainfall, especially in people’s homes.
Storm overflows are normally dilute compared to wastewater, with a high rainwater content, and they may also be screened to remove litter. However the rainwater that runs off roads and fields is also untreated, so contains contaminants and pathogens which are discharged directly into the water environment.
The other problem is that following a request for information from the Environment Agency four years ago water companies admitted that they may be discharging through storm overflows at times other than during exceptional weather events. In these cases there is no dilution from rainwater.
So it's fairly simple. Ask the person who makes this claim if they would swim in it? Whether 5%, 10% or 90% rainwater it's still sewage.
Article published Monday 2nd December 2024