There are 120 consented combined sewer overflows that discharge directly into the River Thames between Windsor and the Thames Barrier.
Fifty-one of these relate to overflows at sewage pumping stations, the remaining 69 are gravity-fed combined sewer overflows.
Thames Water notifies the Environment Agency when the three largest sewage pumping stations at Hammersmith, Western (Victoria) and Lots Road (Chelsea) discharge into the Thames. These are the only overflows that discharge directly into the River Thames which are reported to the Environment Agency. The large discharges from Abbey Mills pumping station overflow at West Ham, made into the Channelsea River, which in turn leads to the River Lea, are also reported as it is close to the Thames.
The Environment Agency is also notified of storm discharges from the Mogden sewage treatment plant in Isleworth.