Raw sewage was discharged into rivers and coastal waters in England for almost 4m hours last year, with waterways that have the highest environmental protections subjected to days of pollution.

Data released by the Environment Agency on Thursday revealed water companies discharged untreated effluent for 3.62m hours, a slight increase on last year.

The data showed that nothing had changed, Giles Bristow from Surfers against Sewage said. “The picture is just as bleak. Despite commitments to investment over the past five years, our water is no cleaner.”