The Honolulu Board of Water Supply last night continued to work on a broken 24-inch water main under Farrington Highway in Nänäkuli and was hoping to complete the repairs in time for this morning's rush-hour commute.

At 9 p.m. yesterday, however, BWS officials said the work may take longer than expected.

"Work is expected to continue into the evening," the BWS said in a press release last night. "It's not known at this time if repair work will be completed by the morning commute."

There were no reports of disruption in water service, but residents from Honokai Hale to Mäkaha were asked to conserve water and refrain from nonessential activities, such as watering lawns, washing cars and doing laundry. Moani Wright-Van Alst, BWS spokeswoman, said the 24-inch main provides about 60 percent of the water to the Wai'anae Coast.

Once the pipe is repaired, residents will be asked to continue conserving water for several hours to allow the BWS to refill reservoirs in the area, she said.

The break occurred about 10:30 a.m. on Farrington Highway near the intersection of Nänäkuli Avenue. Wright-Van Alst said a contractor doing excavation work damaged the line.

Leonard Leong, vice president of Royal Contracting, said one of his company's work crews was installing a sewer line when it struck the pipe. Leong said the BWS had marked the road so Royal Contracting would know where the pipe was, but the markings apparently were covered before the work began.

"We were trenching to install a sewer line and the marking for the pipe was paved over," Leong said. "The previous contractor had installed another water line and they were trying to service the neighborhood by paving it so that people can enjoy the road again. Unfortunately, the workers didn't see the marking so they continued the excavation and that's when they found the pipe."

Leong said it is likely Royal Contracting will pay for the repair work.

"We apologize to the people and hopefully we'll get it repaired and get off the road as soon as we can," he said.

As typically happens during construction or traffic accident investigations along Farrington Highway, police closed two Honolulu-bound lanes yesterday and contra-flowed traffic in the west-bound lanes between Nänäkuli and Haleakalä avenues. That backed up traffic well past the Kahe power plant.