The Case of San Diego's Vanishing Water | Voice of San Diego

Science/Environment

The Case of San Diego's Vanishing Water

Thursday, July 26, 2007 | Each year, San Diego buys about 80 billion gallons of water to deliver to homes and businesses throughout the city. The water courses through hundreds of miles of pipes before reaching faucets.

Along the way, 6.5 billion gallons — 8 percent of the city’s total supply — simply disappears. While that’s below the 10-percent target set by a national association of water suppliers, the loss is still costly.

San Diego foregoes at least $21.8 million annually from the lost water. The city buys it from the San Diego County Water Authority, but doesn’t bill customers for what disappears.

The Water Department is unable to explain exactly where the losses are occurring, whether from faulty meters, leaking pipes or unauthorized use of fire hydrants.

While some cities conduct formal audits of water losses, San Diego does not. The city of Philadelphia, for example, conducts an annual audit to determine where losses occur, how much is recoverable and how much the losses cost the city.

San Diego is not unusual. Four water agencies surveyed in the region provided their water loss rates but couldn’t account for where each missing gallon went. But San Diego’s rate was the highest among those surveyed. By comparison, the Sweetwater Authority, which supplies water to 180,000 South Bay residents, loses just 1 percent of the water in its system.

Water loss is a problem for cities across the nation. In a 2003 report, the American Water Works Association, a national organization representing water suppliers, criticized water agencies for their nonchalance in curbing losses. Citing data collected by the U.S. Geological Survey, the association said the water lost nationally — 6 billion gallons each day — was enough to meet the needs of the country’s 10 largest cities.

“It is striking that even during significant drought,” the report said, “little emphasis has been placed on the need to motivate water suppliers to quantify and control their losses.”

Gabriel Eckstein, director of the Center for Water Law and Policy at Texas Tech University Law School, said water loss and leaky infrastructure is “one of the big hidden issues” for water agencies across the country.

“If we’re so water scarce,” Eckstein said, “how can we allow the infrastructure to leak?”

To calculate its water losses, San Diego subtracts the amount of water it sells from the total amount it purchases. The city also subtracts the water used by the San Diego Fire-Rescue Department, street sweepers and water main flushes.

“It’s a part of doing business,” said Jesus Meda, senior civil engineer in the city’s Water Department. “You’re going to have some unaccounted losses that you can’t pin down.”

The Water Department blames most of the losses on its meters, Meda said, some of which are 24 years old. While leaks and water main breaks compound the losses, Meda said they account for “a tiny percent.”

A water meter works like an odometer. The faster that water flows into a home, the faster a meter’s internal rotor spins. But crust can build up on the rotor, slowing its recording ability — allowing users to receive more water than they pay for. When that happens, the city loses revenue.

Some San Diego meters have been in place since 1983. They’re replaced with less frequency than in some other water districts. The Sweetwater Authority and Carlsbad Municipal Water District said they replace meters every 15 years. The Otay Water District has some 25-year-old meters, but plans to replace all of its meters within the next eight years.

The Sweetwater Authority, which maintains 34,000 meters, replaced 2,400 last year. That’s one in 14.

San Diego, which maintains 272,000 meters, replaced 7,500. That’s one in 36.

“We’ve realized that the meters are the cash box for our system,” said Mark Rogers, the Sweetwater Authority’s operations manager. “We’re trying to keep them as accurate as they can possibly be.”

Replacing San Diego’s meters could benefit city coffers. If meters are responsible for a high percentage of San Diego’s water loss, replacing them would be less expensive than suffering two years of lost water.

Price tag for replacing 272,000 meters (at $99 a pop): $26.9 million.

Foregone revenue from losing 6.5 billion gallons of water: $21.8 million.

The calculation doesn’t include the fraction of water losses from leaking pipes or water main breaks, because the city doesn’t know how much they contribute to the problem.

Arian Collins, a spokesman for San Diego’s Water Department, acknowledged that the city’s meters were problematic and said the department planned to increase its pace of replacements. He was not sure how many meters would be replaced in the next year.

The department’s latest capital improvement plan includes $20,000 more for meter improvements than last year’s plan. That’s enough to replace 200 more meters annually. In a system with 272,000 meters, the increase will replace barely .07 percent of all meters.

“It’s just a matter of priorities,” Collins said. “The infrastructure of the whole water system has been a problem. I don’t think that’s been a secret. We’re working it as fast as we can. But there’s a lot to work on.”

Please contact Rob Davis directly with your thoughts, ideas, personal stories or tips. Or send a letter to the editor.

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