The UK's Environment Information Regulations have enabled researchers and campaigners to force water firms to publish data on river pollution, but they may be scrapped as part of the Brexit process.

"You have to blame the government for this whole sorry mess. The industry is out of control and it's our rivers and beaches that are picking up the tab for that profiteering."

"Just 25 years ago one in four British beaches were too dirty to swim in. Now 95 per cent of our beaches have a clean bill of health."

Huge sections of the UK coastline were too polluted for swimming until EU legal action forced the government to clean up.