The Environment Agency is giving water companies "a licence to pollute" by allowing thousands of "unregulated" overflow pipes to dump sewage into rivers and coastal waters, according to the Marine Conservation Society.
The charity said about 3,500 combined sewer overflows (CSOs), which act as a flood-release mechanism for sewers carrying both sewage and storm water, were in urgent need of review.
It said they have not been properly investigated since being given temporary consent in the run-up to the privatisation of the water companies in 1989.
Coastal pollution officer Thomas Bell said: "There's an obligation on the Environment Agency to have to review these combined sewer overflows.
"The problem is that the sewer system was designed for a climate which is different from the one we have got now.
"Because of the effects of climate change we are having a lot more rain.
"The combined sewer overflows are starting to discharge a lot more often than they should. Their environmental impact is greatly increasing.
"It amounts effectively to a licence to pollute, because there are no restrictions on how much and how often these pipes can discharge."
Among the 3,500 outlets are those flowing into the North Sea, the River Don in South Yorkshire and to a popular Devon beach.
Mr Bell continued: "What we want to see is these 3,500 pipes reviewed quickly so that if any of them are causing serious environmental problems it can be dealt with.
"What we would like to see from the courts are greater fines handed out to water companies for pollution offences."
He also said the combined sewer overflows should be improved to include mechanisms to show how much affluence they are discharging and when.
The Environment Agency said the pipes were designed to operate in times of extreme rainfall.
A spokeswoman said: "We have identified around 3,500 remaining temporary consents for CSO discharges.
"These are mainly for storm overflows that are operating without causing problems.
"As you'd expect, our priority has always been to focus on those consents that are a problem.
"We expect companies to be proactive in identifying intermittent discharges, such as CSO and emergency overflows from pumping stations that are at risk of becoming unsatisfactory."
She added: "The 2007 bathing water quality results announced by Government in November 2007 showed 405 out of 414 bathing water sites in England monitored by the Environment Agency met the mandatory standard demanded under the Bathing Water Directive - a compliance rate of 97.8 per cent."