A deluge of filthy water poured into Pool Street in Poolstock after canal locks were deliberately opened at around 11.30pm on Sunday.
It found its way into around 12 houses, including bungalows used as sheltered accommodation for pensioners.
Simon Connor, crew manager at Wigan fire station, said: “Unfortunately the water started to pour down into the roadway and started to flood bungalows where elderly people lived. We had elderly people who were bedridden stuck in their beds. We had people under water by three or four inches.”
Residents were helped out of their homes and fire crews got to work pumping the water away into the River Douglas.
Engineers from the Canal And River Trust (CRT) closed the locks to stem the flood. Mr Connor said: “Once we got the water stopped from the canal, we could start to pump water back into the Douglas. For the first hour or so we were trying to pump the water away and it was still coming from the canal, so we were just stopping it getting worse.”
The water had all been removed three hours later, but the residents discovered their homes were uninhabitable. Several inches of water had got inside the bungalows and many items had been ruined.
Marie Mason, 70, went to bed at 10.45pm and discovered the water when she got out of bed later to use the bathroom. She initially thought a pipe had burst, but found the water was all the way through her bungalow.
“I saw it coming through the front door like a river,” she said. “I opened the door and the fire service were there.”
Her carpets were covered in water so she plans to stay with her daughter until the carpets and her bed are replaced.
Neighbour Rita Cargill, 69, also had several inches of water inside her house, just 12 months after moving in. She said: “One of my neighbours woke me up.
“She said we were flooded. If I had just got out of bed, I would have had a heart attack because I would have thought, ‘What’s happening?’”
The water damaged all the carpets and flooring, as well as clothes and other items. She spent the night on the couch at her sister’s house but hopes to find somewhere to stay with a bed. Mrs Cargill, who has health problems, said: “They said I can’t stay here. It’s going to take a while for them to repair everything. I didn’t sleep last night, I was too shocked and upset.”
Water also got into the home of Michelle Chapman, who lives nearby. She said: “A neighbour knocked on my door saying there was water on the street. I came out and it was rising fast.”
She unblocked drains to clear away some of the water, but it still got into her hallway.
Mrs Chapman also helped the elderly residents who had been evacuated from their homes. She said: “I have been here for 17 years and I have never had anything like that happen before.”
CRT operations manager Steve Bergquist said: “Our emergency team were alerted to a problem late Sunday evening and we went out to the Leeds And Liverpool Canal near Swan Meadow Lane to investigate what had happened and assisted the emergency services to help restore the water levels.
“Our team is still investigating exactly what has happened but sadly it appears that the canal has suffered from vandalism again with the paddles left open deliberately. Water is very precious and we would ask local people to be vigilant and report any suspicious behaviour to the police.”
A Wigan police spokesman said: “Roads were closed and officers assisted while the fire service and Canal And River Trust resolved the problem.”