The teenagers were attempting the record to raise awareness about the UK's sewage issues.
A "Do Not Swim" notice was put in place at Filey Beach after a sewage discharge on Friday.
Yorkshire Water is investigating a potential misconnection at a private property in Boroughbridge.
An environmental group reports E. coli readings have "spiked alarmingly" in Dorset.
Environment Agency officers believe a recent algal bloom has caused a drop in oxygen in the water.
Gallos Brook Community Group says it has carried out more than 14 tests near RAF Upper Heyford.
The tradition on a Carmarthenshire river once fished by US President Jimmy Carter could be coming to an end.
Several Isle of Wight beaches are under a no-swim warning because of water pollution.
Toxic algae has been found in the capital's first bathing spot in west London.
