Water supplies have been returned to about 8,000 homes in Cardiff after a burst main.
Welsh Water said engineers worked overnight to restore water to properties in the Radyr, Ely, Fairwater and Pentrebane areas.
Customers have been warned that they may experience water discolouration when they first turn on their taps.
Part of Heol Isaf in Radyr was still closed on Friday afternoon following the incident.
Welsh Water said in a statement: "We anticipate that the repair will be completed later today and we hope to reopen one carriageway on Saturday afternoon.
"We aim to have the road fully reinstated and open to traffic by Sunday.
"A diversion route has been agreed with the highways authority and we assure motorists that we will be working as quickly as possible to reopen the road.
"Access will be maintained for residents and emergency vehicles.
"We would like to apologise for any inconvenience caused."
The company said the initial burst occurred at about 1500 BST on Thursday and a second burst occurred at about 0230 BST on Friday.
Cardiff council said Heol Isaf was closed from Llantrisant Road to Woodfield Avenue.