Dozens of beaches are at risk of failing tough new standards for water quality, the Environment Agency said as it launched its summer monitoring programme.
From next year, more stringent European Union regulations will be brought in for bathing spots around England, and the agency is warning that around 40 beaches are on track to fail if action is not taken to tackle pollution ending up in the sea.
They include Scarborough South Bay, Lyme Regis Church Cliff beach, Southend Jubilee beach, Ilfracombe Wildersmouth and beaches at Blackpool, Morecambe and Walney.
If beaches fail on water quality standards under the EU rules, local authorities will have to display a sign advising against swimming.
More than 400 beaches will be tested weekly between now and September, with a total of 8,400 samples taken, and the Environment Agency said nine out of 10 swimming spots were already meeting the new standards.
But there were still areas where pollution was a problem, caused by agricultural run-off, sewage overflows, animal and bird faeces on beaches and households and businesses with badly connected drains, the agency said.
In some areas as many as one in five houses have their drains misconnected, which means sewage is being accidentally flushed into rivers and ending up on beaches.
Water companies, local authorities and the Environment Agency were working to sort out the problem.
Paul Hickey, deputy director of water quality at the Environment Agency said: "The seaside economy in England is worth around £3.6 billion a year - and every improvement in bathing water quality helps to protect that.
"With one year to go until the new EU standards come into effect, the Environment Agency and partner organisations are focusing efforts on the small number of problem sites to bring them up to standard.
"Meeting tough new water quality targets has been a huge challenge, and local authorities, water companies, farmers, homeowners and businesses all have important parts to play in protecting and improving bathing water quality at the remaining beaches that are not yet up to scratch."
The beaches on track to fail the new EU standards, according to the latest assessment by the Environment Agency, are:
North East region - Seaham Beach; Seaton Carew North; Staithes, Scarborough South Bay;
Anglian region - Clacton (Groyne 41);
South East region - Southend Jubilee; Walpole Bay, Margate; Hastings; Lancing, Beach Green; Southsea; Bembridge;
South West region - Lyme Regis Church Cliff Beach; Ladram Bay; Budleigh Salterton; Teignmouth Town; Mothecombe; Seaton (Cornwall); East Looe; Gorran Haven Little Perhaver; Porthluney; Porth; Instow; I lfracombe Wildersmouth; Combe Martin; Burnham Jetty North; Weston-super-Mare Uphill Slipway;
North West region - Southport; St Annes; St Annes North; Blackpool South; Blackpool Central; Blackpool North; Cleveleys; Fleetwood; Morecambe South; Morecambe North; Walney Biggar Bank; Walney Sandy Gap; Walney West Shore; Roan Head; Askam-in-Furness; Haverigg; Seascale; Allonby; Silloth; Spittal.