Thousands of families and workers in Western District spent their New Year's Day queuing for fresh water after repairmen failed to fix a burst water main, despite overnight emergency work.
Michael Yeung Hok-ming, of the Central and Western District Council, said some 40,000 residents were affected.
The Water Supplies Department said the supply had gradually resumed after 9pm, when the repair work was finished.
Earlier, frustrated restaurateurs said they had to turn away customers because of the stoppage, while residents, shocked to find the taps dry, complained about having to take showers in a public community hall.
The 450mm main at 79 Pok Fu Lam Road burst shortly before 11pm on Tuesday, causing the road surface to collapse. Residents said sand and water spewing from a giant hole turned the road into a "yellow river".
Water wagons were used to provide temporary supplies.
Law Kui-hing, owner of Hung Hing Restaurant on Pok Fu Lam Road, said business was "hugely affected" as he and most of his staff had to queue for fresh water. "Look how chaotic it is," he said. "It's going to affect [us] a lot."
Locofama on Fuk Sau Lane turned away walk-in customers to save water to wash dishes. Chef Chan Hok-man said the staff bought bottled water to cook food for those who had booked seats at the restaurant.
Residents said although the supply did not stop until about 4pm yesterday, the flow had been weak since the night before.
"To save the trouble of queuing for water, we'll take showers in the nearby community hall and eat out," one resident said.
Queen Mary Hospital in Pok Fu Lam was not affected.
Central and Western district councillor Nelson Wong Kin-shing criticised the department for the slow repairs. "We can appreciate that there could be some short-term disruption. But almost 24 hours to fix a burst main is not acceptable," he said.
The cause of the burst was not immediately known. But the district councillor believed it was due to ageing of the mains. A scheme to replace and upgrade ageing mains, launched in 2000, is due for completion next year.
Meanwhile, workers last night were trying to repair a freshwater pipe on Queensway and Cotton Tree Drive in Central, which burst at about 10pm.