In 2020,this happened 403,000 times, compared to nearly 293,000 in 2019, a rise which the Environment Agency says is down to increased monitoring.

The Met Office said up to 1.7 inches of rain fell on the southeast coast on Saturday, just under half the average total for the whole of October.

Campaigners are calling for tougher restrictions on overflows to prevent raw sewage being released into rivers and the sea, as figures show a combination of sewage pollution and agricultural runoff mean all of Britain’s rivers fail pollution tests, with harmful consequences for wildlife and wild swimmers.

‘Take all reasonable steps’ to discharge

Last month, the House of Lords passed an amendment to the Environment Bill which would place a duty on the Government and water companies to “take all reasonable steps” to avoid raw sewage being discharged from storm overflows. 

It is currently unclear whether the Government will support the measure.

The Duke of Wellington, who introduced the amendment, said that more investment was needed to modernise the sewage network.

Campaigners say pressure to keep consumers’ water bills low, as well as privatised water companies’ desire to continue payouts to their shareholders, has led to decades of under-investment and left the system unable to cope.