Welsh Water says supplies to up to 1,800 homes in north Ceredigion are returning to normal after freezing conditions affected a water treatment works.
There were problems with the supply at the Strata Florida treatment works on Sunday.
Engineers worked at the site for much of the day to restore supplies.
A spokeswoman said people may at first notice low water pressure or a slight discolouration to their tap water.
This is normal and should clear within a short period of time, she said.
If anyone has concerns about their water, they should call Welsh Water's operational helpline on 0800 052 0130.
