Households in Preston and Lostock Hall woke up to find they have no water on Sunday morning.
Hundreds of homes are thought to be affected across the PR1 and PR5 postcode areas.
United Utilities has traced the problem to a leak near London Way.
An update from United Utilities at 8.14am on Monday (16 October) said: “Our team of engineers have finished repairing the leaking pipe near to Hennel Lane and London Way and the water should be starting to flow normally again.
“We are keeping a close eye on things to make sure your water supply fully restores. It may take up to two hours for the water pressure to return to normal levels. We’re really sorry if this has affected you and thank you for your patience whilst we got this sorted.
“Because there’s been some disturbance to the pipes in your area you may notice the water is a little cloudy or discoloured.”
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The water outage was first reported around 7am on Sunday.
It's on the website now but no ETA of when the waters will be back on. Kettle's empty and so is the loo cistern 😩
— Emma-Louise Cooke 💙 🌱 (@Cooke_EL) October 15, 2017
Engineers arrived on site at the leak at the junction of Hennel Lane and London Way. They began repairs around 11am and quickly updated to say the repair was ‘more complex than originally thought’.
A dedicated incident page has been set up on the United Utilities website.