Up to 64,000 homes could be hit after bungling workmen sliced through a 2ft water main.

And the blunder could mean days of dirty tap water for householders.

Today residents across south and east Bradford were warned not to use washing machines and dishwashers if their supply looked brown - which could last as long as five days.

And to make their water even drinkable they will have to fill jugs and let the water stand so deposits slowly settle at the bottom.

Yorkshire Water bosses are furious at the contractors' blunder - the company could be prosecuted for supplying discoloured water and could face massive bills from disgruntled customers for the cost of bottled water.

The contractor was North Yorkshire County Council's works department, which won the job on tender.

YW has already sent supplies of bottled mineral water and bowsers (water containers) to schools, some companies and vulnerable customers including those with disabilities.

Workmen digging a trench for Bradford Council on Dudley Hill roundabout accidentally cut through the city's biggest water main - 24 inches wide - that supplies tens of thousands of local businesses and homes.

Council bosses today admitted their mistake but added: "These things happen when you dig up the road."

Yorkshire Water bosses must now start a major repair operation and will divert water into the area from other parts of the system while they fix the main. Repair work could also cause traffic chaos.

They expect households to receive discoloured tap water as an unavoidable consequence of 're-zoning' the supply network. Huge areas of Bradford - from Wyke to Fagley - will be affected for up to five days.

"This unfortunate situation was not caused by Yorkshire Water, but we would like to reassure customers we are working as quickly as possible to put things right," said Richard Flint, YW's field-operations manager. "When we start changing the way we pump water round the system, there is always the risk we disturb the fine sediment in the mains. This is what causes discoloration."

Iron deposits in the past been have led to sludgy, gritty water. In several cases, this has led to charges being brought by the Drinking Water Inspectorate.

David Kennedy, director of regeneration at Bradford Council, said: "These things happen when you are digging up the roads."

Mr Kennedy added: "We'd like to apologise that our contractor made an error and we are working with YW to achieve minimum disruption."

Yorkshire Water says for drinking and cooking, you should fill a jug and let it stand. Clear water at the top can be used.

Make sure your supply is not affected before using dishwashers or washing machines. Vulnerable customers will receive essential alternative supplies.

Repair work at Dudley Hill roundabout tomorrow will take five days. Two lanes on the roundabout may need to be closed.

More information from the Yorkshire Water Helpline 0845 124 2424.

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