TENS of thousands of households were without water last night after a freak electricity fault at a treatment works.

The electricity at Broken Scar Treatment Plant in Darlington went off at about 5pm, resulting in dwindling water supplies across the town, as well as homes in the Stockton, Middlesbrough and Hartlepool areas.

Many customers of Northumbrian Water complained that either their water went off completely, was discoloured or had low pressure.

A spokesman for the firm explained that the fault was an extremely unusual one, caused by a problem with the transformer.

The transformer supplies the power used by the pumps to maintain pressure in the water pipe network.

He said: "It's early to say how long it will take to get the water back on, but the first thing is to get the electricity back and we are working closely with Northern Electric to do that.

"That will probably take a few hours and once it is restored we expect it will take a while longer to re-boot the treatment works. This is not an easy job, it's a most unusual circumstance."

He said that some people had supplies longer than others, depending on how long the water in the pipes lasted and added that they were urging customers to use as little water as possible.

"It's hard to estimate exactly how many people will be affected, but tens of thousands of homes and businesses will be without water.

"Some won't see an effect straight away, because there is still water in the system," he added.

A spokesman for Northern Electric said that they had been called out to the treatment works after the faulty transformer tripped one of its circuits.

He said: "The fault caused the volts to dip a little bit, but there was no interruption to the electricity supply.

"The water board asked us to restore the circuits for them, which we did.