Going on a staycation this half-term? Swim at your peril after 46 Britishbeaches have been labelled potential health hazards in Britains' best-known seaside locations - with Blackpool topping the list as the worst offender.
Sewage discharged into the sea is generating dangerous levels of bacteria and viruses, according to the Marine Conservation Society, and no-swimming signs may have to be erected under European rules unless they're cleaned up.
There is, however, also good news: water quality around the coast is getting better in general.
The number of beaches recommended for excellent bathing water – 461 – is at the third highest level in the 24 years of the MCS Good Beach Guide.
But improvements are failing to keep up with the fact that the benchmark of acceptable bathing water quality is being raised.
The MCS explained that EU rules from 2015 will require the health warning signs on dirty beaches.
A spokesman told the Daily Mail: 'Forty-six UK beaches have failed to meet even the basic standards set 35 years ago in European law. These ... are a potential health hazard to beachgoers and could see swimming banned on them after 2015.'
Monitoring for the new EU standards begins next year.
If a beach consistently fails to meet its standards between then and 2015, signs will advise bathers not to enter the water.
Robert Keirle, MCS pollution programme manager, said there is particular concern about the amount of diluted sewage flowing into coastal waters from combined sewer overflows.
These act as emergency outlets for overloaded sewage systems during heavy rainfall. However, they can discharge at other times as well. Mr Keirle said there are 22,000 CSOs in the UK, but just a quarter are monitored.
'MCS wants all pipes mapped and monitored, and for the public to be told ... when, and for how long, the sewage is flowing,' he said.
'Mapping costs relatively little yet it could make the difference between an enjoyable trip to the beach or one that ends up in hospital with ear, nose and throat infections or stomach upsets.'
Responding to its bad results, Blackpool Council is adamant its water is safe, and said test results were affected by last year's 'promenade regeneration' programme.
'The water quality has improved significantly over the last ten years. Unfortunately the bar that we are measured against has also risen,' a spokesman said.
But Blackpool wasn't the only beach who needs to clean up. The top ten worst offenders were listed as: Blackpool, Morecambe, Heysham Sands, Looe, Instow, Lyme Regis (Church Beach), Aberdyfi, Barry (Watch House Bay), St Andrews (East Sands), and Ayr (South).
If you're prepared to head further afield, check out the most glorious beaches around the world below:
The ten best beaches in the world
Bank Holiday swim warning: 46 British beaches told to clean up
Located in one of the top ten best scuba diving destinations in the world, Beaches Turks & Caicos Resort Villages & Spa is located in exotic Grace Bay in Providenciales. It's perfect for families as it has a 24-hour nanny service. Stay at: Beaches Resort Turks & Caicos
Seven nights staying at Beaches Turks & Caicos Resort Villages & Spa on a Luxury Included basis costs from £1,769 per adult and £1,045 per child. Return flights and resort transfers are included in the price. For further information or to make a booking call Beaches Resorts on 0800 597 0001. visit beachesresorts.co.uk.
Boracay is seven miles of Pacific Island heaven, where the order of the day is unwind relax. If you do fancy getting out of your hammock (but why would you?), check out the curious Bat Caves. Stay at: Shangri-La's Boracay Resort & Spa, a stunning hotel situated on a hillside overlooking the sea, boasting secluded beach spots and its own 'spa village'. Visit shangri-la.com.
Visitors from the UK to Aruba have grown by more than 60 per cent in the last two years, attracted by the island's pristine white powder sandy beaches and the idyllic turquoise sea, which looks like its been photoshopped! The seven-mile strip of Palm and Eagle Beach includes a little something for everyone, from wide shaded huts and quiet retreats to busy sunbathing and buzzing beach bars. Stay at: Westin Resort Aruba
Thomson (0871 231 3234) offers a 7-night package, including direct flights from London Gatwick, hotel transfers, breakfast, staying at the five-star recently refurbished Westin Resort Aruba from £722pp, based on two people sharing. Visit thomson.co.uk.
Negril is famed for its natural beauty and laid back lifestyle, and nowhere is this more evident than on the world-famous Seven Mile Beach. Here you'll find one of the island's top resorts and the longest continuous stretch of sand in Jamaica, offering visitors a range of activities from snorkelling and cliff jumping to enjoying the reggae beats and cocktails at Rick's Cafe. Stay at: Sandals Negril Beach Resort and Spa
The holiday: Sandals Negril Beach Resort and Spa is a chic hotel situated on Seven Mile Beach, offering unrivalled facilities including a host of watersports, six restaurants and a relaxing spa. Go to sandals.co.uk.
Tulum is a beautiful old Mayan city, with ruins that sit on 39ft tall cliffs along the east coast of the Yucatan Peninsula on the Caribbean Sea. So it's great for a bit of culture as well as kicking back on the beach. Stay at: A four-bedroom villa on the beach courtesy of homeaway.co.uk. Featuring four bedrooms, two with king beds and balcony facing the sea and two with two double beds each, the villa is secure, private and has a beautiful backyard. One bedroom on the main floor opens to the sea. The property also features an open design communal living area and a large seaside terrace. Sleeps 13, from £1,562 per week. Visit homeaway.co.uk.
The Grand Strand - as the Myrtle Beach area is commonly known - stretches for 60 miles along the South Caroline coast.It's a long-established holiday hotspot, bursting with endless shopping opps, golf courses, amusement parks and waterspouts. Stay at: Myrtle Beach Marriott for amazing ocean views. Visit marriott.co.uk.
Seven Mile Beach has also been voted the best in the Caribbean, so it's pretty hard to beat this near-perfect stretch of sand, which is lined with luxury resorts and bars. There are few restrictions on this beach - open grilling us allowed and pets are free to roam - but avoid playing loud music and stripping off naked, because they're about the only things you're not allowed to do! Stay at: Caribbean Club
The five star Caribbean Club is located directly on Seven Mile Beach and offers guests two bedroom and three bedroom all-suite accommodation. All rooms have large balconies that look out onto Seven Mile Beach with sun loungers and a table and chairs. Prices start from US 450 for a two bedroom or US 680 for a 3 bedroom suite based on double occupancy. Subject to 10% government tax and 10% service charge. (May 1 to 15 December 2011). Visit caribclub.com.
Sitting at the southern tip of New Jersey, Cape May is a small seaside holiday resort with a population of 4000 - which swells to 40,000 in the summer months, giving an indication the popularity of its beaches and historical charm. Stay at:Virginia Hotel - a gorgeous collection of upmarket cottages in the historic area of Cape May. Visit capemay.com for more information, and blacktomato.co.uk for great holiday ideas.
Surf fans, listen up! Santa Teresa has world-class waves and is a sea-rider's paradise, busting with surf shops and camps. But you don't have to love surfing to love Santa Teresa. Just soak up the sun on the pristine beach, check out the jungles surrounding it, or visit Costa Rica's nature reserve, Cabo Blanco, and enjoy its live music nights and exciting nightlife. Stay at: The White House - a stunning open-plan house on the beach. An architectural masterpiece with a private infinity pool, the property is next door to Pranamar, the newest and most beautiful yoga resort in Costa Rica and consists of a large four-bedroom beachfront estate home, and two smaller two-bedroom villas. Eight bedrooms, sleeps 17, from £638 per per week. Visit homeaway.co.uk.
Punta Cana offers all the dreamy fun you'd expect on a Caribbean holiday: horse riding on the beach, snorkelling and parasailing. Don't miss a trip to the South American village of Altos de Chavon, and take a speedboat to the beautiful Isla Saona. Stay at: Tortuga Bay - a collection of 15 luxurious beachfront villas decorated by none other than Oscar de la Renta. Visit fivestaralliance.com