A water company is warning people to stay out of its sewers.
Severn Trent, which supplies thousands of homes in the East Midlands, claims a small number of people have started exploring the sewer network.
So-called urban adventurers like to go in places like derelict buildings or underground sewers, film themselves and put the images on the web.
But water company bosses say the hobby is dangerous and could end up with someone being killed.
Ben Usher, Severn Trent's sewerage networks manager for the East Midlands, said: "I've looked at the websites and it's quite horrific, the lack of equipment and preparation these people have taken before they've got into the sewer.
"The dangers are that, it's unlit, it's very slippy, there's oils and greases, there are gases there that people can't detect without the right equipment.
"And the other problem we've got is that when people get down there, if they did have an accident, clearly it's very difficult to get them out of the system."
Advertisement
People who take part are known as urban adventurers
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.
Bookmark with:
What are these?