Dealing with wastewater in London

Reducing wastewater discharges into our rivers
London’s sewage system dates back to the mid-1800s. It includes emergency overflows into the Rivers Thames and Lee to avoid flooding streets and homes with sewage during particularly heavy rainfall.

There are 57 overflows, which discharge diluted sewage into the Thames 50 to 60 times a year. Widespread heavy rainfall can lead to over a million tonnes of untreated sewage and rainwater spilling into the rivers.

These discharges are unacceptable. We are working with Thames Water and other partners to support the construction of two tunnels that will carry away storm wastewater to Beckton sewage treatment works. These tunnels will greatly reduce storm discharges and improve the quality of the water in the River Thames.

Tackling sewer misconnections
Pollution in our rivers also comes from sewer misconnections, where household appliances are connected to the surface water drain rather than the sewer. Thames Water estimates that one in every 20 houses in London has a misconnection. We propose that the Royal Institute of Chartered Surveyors consider including a survey of sewer misconnections as part of the surveys at the time of sale of a property.

Fighting the fat, oil and grease
Fat, oil and grease (FOG) can be a major problem for sewer systems – blocking them up and causing flooding and pollution as a result. Restaurants are a major source of FOG. But the FOG can not only be collected but often converted into biodiesel.

Energy can also be generated from sewage gas and we are committed to working with Thames Water and other partners to identify ways to turn sewage into renewable energy and reduce emissions of greenhouse gases.