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."