Residents in Preston are complaining of discoloured or brown water coming from their taps.
But North West water company United Utilities has urged residents not to worry.
A company statement reads: "We have received calls to let us know some of you are finding when you turn your tap on the water is discoloured or brown in colour.
"This has happened because of a disturbance to the pipes in your area. Our pipes have naturally occurring sediments and minerals at the bottom which can get disturbed every now and then.
"We know it doesn’t look nice but don’t worry, it’s unlikely to be harmful and will settle down again with time.
"You can help with this by letting your cold water tap run at a slight trickle until your water runs crystal clear again."
A United Utilities inspector is monitoring the issue to ensure that the disturbance settles back down again.
The firm has also apologised for the inconvenience.