Thousands of people in Derbyshire have been warned not to use their water supply after fears it may have become contaminated with abnormal amounts of chlorine.
Severn Trent said in a statement that residents in the DE11, DE65 and DE73 postcodes should not turn on their taps after they found higher than usual levels of chlorine at the Castle Donington reservoir in Derbyshire.
At least 3,500 Severn Trent customers across the two counties are believed to be affected.
A spokesman told the BBC they did not know how long the disruption will last and the Do Not Use warning including drinking, bathing and washing.
Confused residents took to Twitter to vent their frustration after the company initially said the LE65 in neighbouring Leicestershire was affected before removing it from their website without explanation.
A spokeswoman for the company confirmed the water was safe in the area and apologised for the confusion.
Residents have already been queuing for emergency water supplies handed out by Severn Trent at sites around the affected area.
One local resident complained on the BBC Radio Derby Facebook page that her elderly father had been drinking the water because he did not have access to the internet.
Shirley Goodall said: "Dad in DE15 area, almost 83 years old, just phoned him ...too late has had his dinner and cups of tea. Not an Internet user or a local radio listener.....no note or phone call from the water company!"