BRA and pair of knickers were to blame for a flood that damaged more than 20 homes and caused excrement to flow down a street.
Northumbrian Water said yesterday that the underwear had been flushed down a toilet - but later snagged on a sewage pipe under a busy road.
Water could flow past the bra - which caused the sewer to collapse, and inturn caused the road to crack open on Friday.
Dirty water and excrement flowed down Middleton Lane in Middleton St George, near Darlington, and into people's homes.
The road will be closed for another five days - causing buses to be re-routed - and Northumbrian Water estimate repairs will cost more than £15,000.
The company are now urging all residents to think carefully about what they put down the sink and toilet.
"If the bra and knickers hadn't been put down there, we don't think the sewer would have collapsed. It was extremely irresponsible behaviour."A spokesman for Northumbrian Water
A Northumbrian Water spokeswoman said: "When we dug down, we found a bra and knickers had snagged itself across the nine-inch diameter of the pipe.
"There was also a heavy build-up of grease and fat. The pipes are not designed to carry that, and they're certainly not designed to carry bras and knickers.
"We encourage people to bag and bin anything that isn't water, basically. If the bra and knickers hadn't been put down there, we don't think the sewer would have collapsed. It was extremely
Northumbrian Water cannot pinpoint where the underwear was flushed, but believe it was local. A two metre section of collapsed sewer has been replaced.
Middleton St George residents reacted to the flood by claiming the pipes were not fit to cope with the village's increasing population.
Coun Doris Jones, from Darlington Borough Council, maintains the sewers need replacing - despite the underwear discovery.
"I just can't accept that's been wholly responsible," she said. "The main problem is the sewers just can't cope - they really are antiquated."
Coun Jones added pensioners had been forced to use expensive taxis because of bus diversions.
The Northumbrian Water spokesman said a full camera survey of the pipes around Middleton Lane would be carried out, and added a "catchment study" would examine the whole area.
"We are aware of the problems and are trying to resolve them," she said.