Less top bathing beaches
The number of UK bathing spots scoring the top rating in the annual Good Beach Guide has fallen by a record amount this year - largely due to last year's wash-out summer.
Thomas Bell, the charity's coastal pollution officer, said the testing was carried out between May and September last year and the severe summer storms had skewed the scoring.
"These latest MCS results buck the long term trend of cleaner bathing water but we're pinning the blame squarely on last summer's exceptionally bad weather," he said.
"Heavy rain sweeps pollutants like raw sewage, street debris and animal waste directly from the land into rivers and the sea. Not all beaches are affected but the problem for swimmers is knowing when and where this has happened."
In total, 443 (57%) UK beaches are 'MCS Recommended' this year out of 778 tested, compared to 495 last year.
Mr Bell added: "The 443 beaches we're recommending shrugged off the worst of last summer's weather, which is good. But poor quality bathing water carries health risks, so if this summer is wet then I'd advise people to use the Good Beach Guide, pick bathing beaches with a good record, and stay out of the sea for at least 24 hours after heavy storms."
MCS Recommended is one of five UK beach awards, but is the only scheme that focuses entirely on water quality standards and the risk of sewage pollution.
MCS will only recommend beaches in the Good Beach Guide if they are better than the Guideline European water quality standard and are not affected by inadequately treated continuous sewage discharge.