Most of the sewage we treat is organic which is why we use natural, organic processes to treat it, which involves bacteria breaking down waste.
After we treat wastewater, it is released back into the sea and streams, which will include some bacteria.
Our water recycling centres are almost 100% compliant with environmental standards, which means there is no adverse effect on wildlife.
The purpose of treatment processes is to achieve standards that protect the environment rather than public health.
Learn more about the water recycling process.
Why can’t we change the way we treat wastewater?
At some popular coastal sites, additional disinfection treatment (using ultraviolet light) has been installed at our water recycling centres to meet increased public health standards.
This comes at a significant cost to the environment in terms of tonnes of CO2 emitted from the increased energy use of this disinfection process. We currently use an estimated 3,843,000 kWh to power this UV equipment. Most of the sites are required to dose 24/7 throughout the year even when no one is benefitting from it.
Taking a similar approach at inland treatment sites – to kill bacteria to meet bathing water standards – would cost many hundreds of millions of pounds to build suitable treatment processes and millions of pounds to operate each year.
In addition, the environmental impact would be thousands of tonnes of additional CO2e (carbon dioxide equivalent) emitted each year.
This is diametrically opposite to the direction of travel that we as a business and as a country are trying to achieve to combat our climate crisis. As a business we have committed to achieving a net-zero carbon footprint by 2030 – some 20 years ahead of the whole country.
Disinfecting at these sites to reduce the public health risk for swimmers would need support from customers, the Environment Agency and Ofwat. It is not just a water company decision, but we’re happy to engage with those who are thinking about bathing water designation for inland rivers.
Heavy or prolonged rainfall can rapidly increase the flow in a combined sewer until the amount of water exceeds sewer capacity.
Storm overflows act as relief valves, allowing excess stormwater to be released to rivers or the sea.
This protects properties from flooding and prevents sewage from backing up into streets and homes during heavy storm events.
As storm overflows should only operate during periods of intense rainfall, any foul water released from them will be very dilute because of the large volumes of rainwater within the system.