When a 2-foot-wide, cast iron water main broke beneath the H-1 freeway in Kahala in January, workers had to dig a gaping hole nearly 20 feet deep, and repairs took several days. A nightmarish traffic backup ensued, and the Waialae Beach Park was temporarily closed.

Two months later on a sunny afternoon in nearby Palolo, residents stood in their driveways, watching water shoot out of Pakui Street from a broken 16-inch cast iron main. The plume could be seen for miles as it rained down on a house across the street.

Sheila Niderost pointed to white lines around the break that she said were painted about a month earlier when the pipe had previously burst.

Like many Palolo residents, Niderost’s home has been in the family for decades. She can recall several main breaks on Pakui Street, including one 20 years ago that damaged her car and flooded her house and yard. The road cracked down the middle, and boulders rolled off the Wilhelmina Rise hillside at the end of her street.

“That was the worst I’ve ever seen it,” she said.

While some cause a lot more trouble than others, ruptures occur almost every day somewhere along Oahu’s 2,100 miles of water pipes.

Oahu has more water main breaks than most mainland cities of similar size. Unique island factors like underground lava tubes and corrosive clay soils — along with an apparent longtime unwillingness to charge people the actual cost of delivering their fresh water — are often blamed.

Whatever the cause, Honolulu faces a mammoth challenge in upgrading its water infrastructure. The Board of Water Supply aims to replace 1 percent of all pipes in the system annually, which would cost an estimated $160 million each year in current dollars.

BWS is considering another multi-year rate increase to help pay for the work. Even after fees were raised from 2012 to 2016, Oahu water users pay less than what is needed to operate and maintain the water system, according to a University of Hawaii professor and engineering expert.

Fixing the breaks at their current frequency costs the BWS about $3 million a year, and that doesn’t include the expense of wasted water and traffic congestion caused by the detours around Oahu’s impromptu fountains.

Anthony Quintano/Civil Beat

It’s Worse In The Valleys

The soil in Palolo Valley corrodes water mains, said George Braun, a BWS pipefitter who was working on the recent break there. Corrosive soil is probably “more unique to Hawaii,” he said, which is why more modern pipes made of PVC — a type of plastic — are often installed in some areas.

Valleys like Palolo tend to have more breaks because of soil type and movement. Sections of the island with more people and older pipes also have more problems.

Cast iron pipes, like those under Pakui Street, are the most common pipes on Oahu. They’re also the oldest (some were installed as long as a century ago) and the most likely to break.

“This is one old area,” Braun said.

The BWS claims in a fact sheet that its number of main breaks is “far fewer than the American Water Works Association’s recommended maximum,” but many mainland cities have fewer.

Civil Beat contacted water service providers in 10 cities of similar population size, as well the water departments in New York City, Los Angeles and Chicago — the most populous cities in America.

Water main breaks were calculated per 100 miles of pipe.

The AWWA, which develops guidelines for water providers, set its recommended maximum number of breaks at 25-30 per 100 miles of pipeline per year. There will always be some breaks, but a level higher than that is excessive, according to the association.

Nine of the 13 cities surveyed had fewer breaks per 100 miles of pipe than Oahu last year.

The chart below shows water main break averages:

Ken Ota, the Hawaii director of AWWA, owns Pacific Pipe Company in Pearl City. As a retailer, Ota said he sells to contractors who work with BWS and connect pipes to main lines.

“I sympathize with the Board of Water Supply because (repairing main breaks is) based on manpower … time management, it’s hard for them,” Ota said. “I feel their pain because it’s something that’s ongoing, battling our problems that we face in Hawaii of controlling corrosion.”

Honolulu isn’t alone in its struggles with water infrastructure.

Nationwide, about 240,000 water mains break each year, wasting an estimated 2 trillion gallons of drinking water, according to a report by the American Society of Civil Engineers.