More than 60,000 people sweated out one of the hottest weekends of the year without mains water following a fault in a pumping station.
Thousands of households as well as children's and old people's homes were affected by the pipe-burst in Halifax, West Yorkshire, which happened at midday on Saturday.
Yesterday about 100 households out of the 20,000 affected were preparing for a second night without water.
Yorkshire Water officials apologised for the loss and said they were doing all they could to restore supply.
Urgent repair work had allowed water to flow back to most households by yesterday evening but Yorkshire Water was concerned they might be cut off again if further faults developed.
Spokeswoman Tracy Wood said one of the pumps was "lasting on a wing and a prayer".
"We're telling people not to wash cars, use washing machines or dishwashers or anything that takes up a lot of water just in case the supply fails again."
The warnings came three weeks after a hosepipe ban was imposed on the area.
During the weekend residents quenched their thirst by boiling water provided by standpipes and delivered in tankers touring the affected areas.
Yorkshire Water's entire fleet of 150 tankers were on the streets ferrying water to the affected districts, receiving help from North West Water and Severn Trent Water.
When the fault occurred, temperatures in the Halifax area were soaring into the mid-80s, one of the hottest weekends the area has seen this year.
The town's three hospitals escaped the shortage and local ambulance teams said fears of people collapsing due to dehydration had not been realised.
However, many were faced with discomfort. Phil Needham sweated it out with his girlfriend and three children, unable to shower or flush the toilet.
"Things are pretty hard. We're using a water store in the loft but when that runs out we've had it," he said.
"I had to pull some water from the reservoir just for flushing the toilet. The nearest standpipe to us is about two or three miles away. It's OK if you've got a car but if you're old or ill you've got no chance unless someone gets it for you."
Shadow consumer minister Nigel Griffiths yesterday called for an inquiry into the fault. He said customers "let down by Yorkshire Water ...are entitled to know what the directors have done to deserve pounds 869,000 in share option profits".
"What performance are these related to when they can't even maintain a basic water supply to their customers?"
Yorkshire Water spokesman Gerry mac Griogair could not confirm the figures and said share options were not relevant to Halifax's water shortage.
"This is a technical matter. It has nothing to do with directors' share options. Our directors haven't received share options for three years and in May we announced we were officially ending the share option scheme," he said.Reuse content