People living near the brook in Wolverhampton say they have had to put up with a stink coming from a 'grey sludge'.
Edward Hughes, 44, a director of a property development company, often visits the natural brook and spring close to his home on Pencroft Lane, Penn, with daughter Grace Hughes, 11 and his wife, Victoria Hughes, 42, also a joint company director.
They live close to Severn Trent water treatment plant on Red Lane and, around six months ago, noticed an increase in bad smells coming from the water that runs from Pugh's Farm.
Investigating further more recently, they discovered sludge filling up the brook and spring which they believe is raw sewage. The house and gardens date from 1802 and the family have owned the property for the last 15 years.
Mr Hughes said: "It's absolutely disgusting. We expected the smells because we're close to farm land and the treatment plant, but when we saw what was going into the water, it was unbelievable.
"My daughter and I would spend time going out to the brook with nets to catch little fishes but this sewage has killed everything off."
The family are concerned about the impact of the leak on other wildlife.
Mr Hughes said: "This is a historic brook that runs through Pugh's Farm, us, right down through Wombourne into the River Stour and eventually into the Severn. The thought of this passing through, with animals drinking it and children playing in the wild pools, it's horrendous."
The site was visited by officials from Severn Trent last week following the family's complaint, but they were unable identify the source.
Mr Hughes said: "I couldn't believe it when they came up to my fence right by the brook to say they couldn't find the source. I said to them 'wait there and I'll come round and show you' but by the time I got round there they'd gone.
"I've been out with my dad right along the stream and there was a huge pile up of sewage and what looked like soiled tissue as well.
"Something drastic needs to be done before this gets any worse."
A spokesman for Severn Trent said: "“On Tuesday, June 20, we became aware of a blocked manhole just inside our treatment works and our teams have been working to clear the blockage since then. When the blockage was cleared, it was found to be a ball of rags – made up of things that shouldn’t be flushed down the toilet such as wipes.
“There has been some flooding from the blocked manhole which has made its way into the field adjacent and we’re really sorry this has happened. We’ve been speaking to the owner, and we’re currently working with him to come up with the best way for us to clear up. We’re also arranging a CCTV survey of this particular sewer to make sure there are no further issues.
“As we said, the blockage was made up of wipes and other things that shouldn’t be flushed into the sewers, so we’d like to take the opportunity to remind our customers of the 3Ps – the only things that should go down the toilet are pee, paper and poo. We currently clear around 50,000 blockages each year, of which three quarters are down to sewer misuse, and can lead to issues with blockages and flooding like this.”