Leeward Coast residents are coping with the latest in a long-running saga of severe traffic headaches there, as a ruptured water main has choked off access along Farrington Highway in Nanakuli and left some 15 homes without water.

Repair crews have been working around the clock since the 24-inch PVC water main broke around 6:30 p.m. Thursday near Pohakunui Avenue, shutting down lanes and slowing the evening commute to a crawl.

They hope to have the main’s 20-foot crack repaired today and the road fixed Sunday, but Board of Water supply officials say it’s hard to say “definitively” how long the repairs will take.

The rupture closed all eastbound lanes of Farrington between Pohakunui and the Kahe Power Plant, and reader-submitted video Friday showed streams of water gushing into the ocean. Had the break occurred only a few hundred feet up the road, commuters would have been able to use Pohakunui as a bypass road to Farrington, BWS officials said.

The water main supplies 60 percent of the water to the Leeward Coast, and BWS officials asked all residents from Honokai Hale to Makaha to conserve water. “This means using water for essential needs only, such as cooking, drinking, and personal hygiene,” a news release said.

As the afternoon rush hour intensified Friday, traffic officials used the two available lanes to let only Waianae-bound traffic pass. They intermittently opened one of those lanes to town-bound traffic, according to HPD Assistant Chief Clyde Ho.

City crews also manually adjusted the traffic signals heading into Nanakuli to help keep vehicles flowing, according to city traffic engineer Ty Fukumitsu.

More than 45,000 residents live on the Leeward Coast, and the area sees about 43,000 vehicle trips a day, officials say. With Farrington offering the only major route into and out of the area, residents there regularly grapple with some of the island’s worst traffic.

City transportation officials asked their federal counterparts to temporarily open Kolekole Pass but they were told that wasn’t possible, according to Department of Transportation Services Acting Director Jon Nouchi.

Officials said customers in Nanakuli are experiencing either low water pressure or no water service. BWS officials said they would send water wagons roving through neighborhoods to help assist affected customers.

“If you see a water wagon coming by your street … just flag them down and say you need water and they’ll stop and let you fill your containers,” BWS Chief Engineer Ernie Lau said at a press conference Friday.

BWS will also set up a water-tanker station near Nanakuli High School, he added.

The pipe that cracked was installed in the early 2000s, Lau said. Typically, BWS has noticed that its PVS pipes are more susceptible to breaks from sharp rocks, he said, but the agency is still investigating what caused the rupture.

Crews plan to replace the broken PVC pipe with an iron one, said Mike Fuke, a BWS program administrator for field operations.

BWS manages 2,100 miles of pipe on Oahu, including 350 miles of PVC pipe, Lau said. Its recent 30-year master plan calls for about 1 percent of the pipe to be replaced a year — but that will eventually require more revenues from its ratepayers, he added.