LOS ANGELES — The rupture of a nearly century-old water main that ripped a 15-foot hole through Sunset Boulevard and turned a swath of the University of California, Los Angeles into a mucky mess points to the risks and expense many cities face with miles of water lines installed generations ago.
The flooding that sent more than 20 million gallons of water cascading from a water main came in the midst of California's worst drought in decades and on the same day that tough new state fines took effect for residents who waste water by hosing down driveways or using a hose without a nozzle to wash their car.
Much of the piping that carries drinking water in the country dates to the first half of the 20th century, with some installed before Theodore Roosevelt was in the White House.
Age inevitably takes a toll. There are 240,000 breaks a year, according to the National Association of Water Companies, a problem compounded by stress from an increasing population and budget crunches that slow the pace of replacement.
"Much of our drinking water infrastructure is nearing the end of its useful life," the American Society of Civil Engineers said in a report last year, noting that the cost of replacing pipes in coming decades could exceed $1 trillion.
The association of water companies says nearly half of the pipes in the U.S. are in poor shape, and the average age of a broken water main is 47 years. In Los Angeles, a million feet of piping has been delivering water for at least 100 years.
When taps are running and swimming pools are brimming, no one pays attention to water lines, typically invisible underground. But the country has reached a point where vast lengths of pipe are wearing out at about the same time, said Greg Kail of the nonprofit American Water Works Association.
"Water pipes last a long, long time but they don't last forever," he said. "There is a lot of pipe in the ground and there is an enormous expense, collectively, in replacing it."
The 30-inch pipe that burst Tuesday near UCLA shot a 30-foot geyser into the air that sent water down storm drains and onto campus. The pipe was still gushing 1,000 gallons a minute on Wednesday and officials said repairs could take another two days.
At its peak, water was gushing out of the break in the riveted steep pipe at a rate of 38,000 gallons a minute. The amount of water spilled could serve more than 100,000 Los Angeles Department of Water and Power customers for a day.
The pipe had been worked on before. While the cause of the break remained under investigation, Mike Miller, a district superintendent for the city Department of Water and Power, said the crack occurred near a connection where the 93-year-old water main joined a pipe installed in 1956.
The pipe must be dry for repair work to begin, but on Wednesday leaky valves above the break allowed water to continue seeping in. Shutting off valves and pipes creates the risk of more ruptures in the 7,200-mile system, especially on hilly areas in and around campus.
The reputation of Los Angeles for producing the next new things in style and culture doesn't extend to its creaky infrastructure. The city is decades behind in repairs to cratered streets and sidewalks and some of its water lines have been around so long that William Mulholland could have seen them going in.