Natalia Maca walks past the stream in Huntingdon, Cambridgeshire everyday and has seen the soapy liquid bright green and blue.
The 35-year-old said: "I walk past there a lot. It changes colour, sometimes it's blue, sometimes it's green. "It's not just the one day it happens nearly everyday. It's been happening for months."
Speaking to the Daily Mail, she said: "I've called up the Environment Agency and they just keep giving me a reference number and say that they will report it and investigate but nothing has changed.
"It's a soapy liquid but I have no idea what it is - I'm no expert. I've spoken to a couple of locals and they don't know much either."
According to Cambridge News, dogs are reportedly falling ill after swimming in water nearby. Industrial areas around Huntingdon are being checked to find the cause of the coloured water.
World's most dangerous beaches
World's most dangerous beaches
You don't have to go to exotic shores to find dangers lurking in deceptively calm waters. Morecambe Bay, in Lancashire, is notorious for its quicksand and fast moving tides, which took the lives of 23 Chinese cockle pickers in 2004. Visitors should only cross the sands of Morecambe Bay with an official guide.
Poor old Bikini Atoll was once just a beautiful group of islands in the South Pacific. Then, in the Forties, it became notorious for two things: providing the name for the saucy new two-piece swimsuit, and being chosen by the US as the site for nuclear testing. The amounts of radiation that still exist in the food chain have made it impossible for the Bikini Islanders to return to their homeland, although tourism has been introduced to the ship graveyard dive site in Bikini Lagoon.
An unofficial wooden beach sign at Hanakapiai on Kauai island shows more than eighty tally marks representing those who've drowned there, official reports put the number at thirty. Either way, the rip currents here are so treacherous, the sign's warning not to go in, or even anywhere near, the water is worth taking very seriously indeed.
Other beaches might have more frequent shark bite attacks, but nowhere are the sharks more aggressive and the attacks more likely to be deadly than in Port St Johns, on South Africa's southeastern coast, which has seen six fatal shark attacks in just over five years. Locals believe the bull sharks here are particularly blood-thirsty because witch-doctors make animal sacrifices on the beach, throwing the entrails into the sea.
Just when you thought Chowpatty Beach couldn't get any dirtier, a cargo ship sank off the coast in 2011, its load of 60,000 metric tons of coal polluting the water even more. Despite the layer of rubbish on the sand, locals still use the beach for their evening promenade, and even venture into the water every September during the festival of Ganesh.
Ok, as far as we know no one's ever actually been hit by an airplane while innocently sunbathing on St Martin's Maho Beach, but you only need to take a look on Youtube to see how dangerous getting up close to the jets can be as they take off from the scarily close airport. Blown away, literally.
A relaxed attitude to nudity and soft drugs may attract many travelers to the stunning hippy haven of Zipolite, but it's name - The Beach of the Dead - and the fact that there is a cliff at the far end of the beach covered in crosses to mark those who've died at the mercy of the powerful rip tides - reveals a rather scarier side of paradise.
Volusia County, Florida holds the dubious honor of being the world's shark bite capital, with 231 reported attacks from when records began in 1956 and 2008. And if the sharks don't get you, a bolt from the sky just might, as Central Florida has more lightning strikes than anywhere else in the world.
It's a cruel trick of nature that water as beautiful and clear as that surrounding Australia's Fraser Island conceals sharks, jellyfish and rip tides so dangerous you can't swim in it. Dry land's got its fair share of potentially fatal fauna too, including dingos, Funnel web spiders and pythons.
The waters off Recife are so shark-infested that even the lifeguards don't go in the sea any more, training in a nice, safe swimming pool instead. After 56 shark attacks in the last twenty years - 21 of them fatal - surfing's been banned, and if that's not enough to put you off, the fact that most of Recife's sewage runs untreated into the water, just might.
Kilauea is one of the most active volcanoes in the world. Lava flows onto the beach and into the sea, making the water temperature a whopping 110C.