The fault meant water could not be disinfected as normal, and engineers have been working round the clock to fix the situation.
The company has also made changes to the water supply network so that some parts of Bolton have been getting their water from a different treatment plant at Wayoh. Water on Wheels tankers were also been deployed to pump water into pipes in the area and top up supplies. These measures have helped to reduce the number of homes affected, it said.
UU said that it expected the remaining 2,300 of the 18,000 properties affected to have their water restored today. However, all of the affected properties have been advised to boil water before using it for drinking or food preparation.
UU water network manager Paul Forshaw said: “We know how inconvenient it is to be without water, and we have been working round the clock to get things back to normal since Sunday.
“There are hundreds of miles of pipework in Bolton and large water storage tanks which all have to be refilled before supplies reach all our customers. We have refilled the system slowly to avoid causing any burst pipes or causing discoloured water, and this has taken some time.”
This article first appeared on WWTonline.