Residents in Exeter have been told to turn on their taps and flush out discoloured water after it turned a dark shade of brown.
The problem has affected homes in Newport Road, Countess Wear, close to where contractors are digging trenches where new homes are being built.
Resident Rob Stoneman said he has had to run taps for hours before the discoloured water clears at his home in Newport Road.
Technicians from South West Water have visited his home, but it is not clear what has caused the problem.
He said: "I've had to run the taps for a couple of hours until the water runs clear. I won't drink it – we're using bottled water. The man from South West Water was very helpful and friendly, but they don't seem to know what's caused the problem – it's not a good situation.
"We can't do the washing or run a bath – and we can't seem to get a proper answer about what's happening."
Mr Stoneman said he knew of lots of other residents living nearby who have been affected.
He said building work in the area was likely to go on for several weeks, and it would be unacceptable if his water is affected for that length of time.
Councillor Marcel Choules, who represents people in the areas, said: "Sometimes these things are unavoidable when work is being carried out, but residents need to be informed – they need to know and be told what's happening with their water supply, and the communication hasn't been good."
A spokeswoman for South West Water said residents who have to run their taps to clear water would be entitled to money off their bill if they are on a meter.
She said: "A technician attended a property in Newport Road after we received reports of discolouration in the area.
"We flushed the network to clear and advised affected customers they could help by running their cold water tap at the kitchen sink. Customers on a water meter can apply for a run off allowance."
