Nearly 1 in 10 gallons of water vanishes as it flows through pipes and mains in Sacramento’s antiquated drinking-water utility system.
That’s an estimate. No one really knows for sure how much water is lost. Almost half of the city utility’s nearly 126,000 residential connections don’t have meters tracking and tallying how much they use. Because of this, there’s no way of precisely knowing how much water goes missing because of leaky pipes, loose connections, theft or at city hydrants.
Officials at Sacramento’s Department of Utilities aren’t the only ones in the region guessing at the percentage of the water that disappears from municipal pipes.
“We don’t know if we’re over 10 percent. We could be. We could be at 1 percent,” said Rob Roscoe, general manager of the Sacramento Suburban Water District. “I don’t think so because we’ve got a lot of old mains. The point is, we don’t know exactly where we are until we’re fully metered.”
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In his district, around 75 percent of its 46,112 connections are metered.
In the fourth year of the worst drought in California’s recorded history, these systemwide losses and the difficulty in tallying them represent a substantial challenge for urban water districts trying to comply with Gov. Jerry Brown’s executive order mandating a 25 percent cut in urban water use by February.
If Sacramento utility officials’ estimates are accurate, last year more than 3.3 million gallons in the system never made it to ratepayers.
The officials say they’re aggressively addressing the problem with a goal of having almost all customers fully metered by 2018.
“We’ve got a big push between now and then to get a lot of meters in the ground,” said Bill Busath, Sacramento’s utility director.
They’ve also received nearly $2.7 million in grants to begin installing sophisticated leak-detection technology in already-metered neighborhoods.
Part of the challenge in Sacramento is that the majority of the city’s pipes and water mains are between 60 and 100 years old. As they degrade, small leaks pop up and water seeps into the ground.
As at other utilities across California, both the city and the Sacramento Suburban Water District, which has similarly decrepit water infrastructure, have responded in the drought by replacing aging mains, installing meters and ramping up leak-detection efforts. In the city, officials added a second crew armed with sonar systems to comb the city listening for leaking pipes.
Busath says the hope is that as the city expands its real-time leak-detecting and metering technology, crews will be able to home in on suspected trouble spots, instead of randomly trying to find leaks in what are now neighborhood-by-neighborhood testing schedules.
Because there are so few meters, the city utility is for now relying on mathematical modeling to create water-loss estimates. They’re based on precise measurements of how much is pulled from rivers and pumped from aquifers and how much flows through the connections of already metered customers scattered through the city.
Based on these known quantities, Brett Ewart, a senior engineer at Sacramento’s water utility, estimates the city’s overall losses this year at between 9 and 11 percent.
The American Water Works Association at one point recommended utilities set a maximum 10 percent benchmark for what’s known in utility parlance as “unaccounted for” or “nonrevenue” water. The trade group has since stopped recommending a percentage benchmark and now encourages utilities to conduct individual water-loss audits.
Many utilities, including Sacramento and Sacramento Suburban, include in this category water from hydrants used for firefighting and construction or what’s used to flush mains, blast out sewer backups and other legitimate maintenance.
Sacramento’s estimates also aren’t that out of line from regional water districts that are fully metered.
Officials in fully metered Roseville estimate their water loss last year at 9.24 percent. Keith Durkin, assistant general manager at the Granite Bay-based San Juan Water District, pegged his metered utility’s loss at 7 to 8 percent.
In 2014, the California Public Utilities Commission queried nine of the state’s largest privately held water utilities on how much lost and unaccounted for water disappeared in their systems.
Commission spokesman Andrew Kotch said the utilities, which represent about 96 percent of California customers served by private utilities, reported losses of between 2 and 7 percent, with an average of about 5 percent.
At least one expert is skeptical of California’s water districts reporting such low numbers.
Madelyn Glickfeld, director of the Water Resources Working Group at UCLA, said that some countries, including drought-plagued Israel, employ a much more sophisticated leak-detection technology systemwide than California’s utilities do, yet they rarely report losses of below 10 percent.
Glickfeld says she’s also troubled that California’s utilities routinely lump all water losses together instead of breaking them down by how much is lost specifically to leaks or breaks. Water-loss audits, she says, also are left to the discretion of a utility.
California lawmakers appear to be listening to such concerns. State legislators are considering Senate Bill 555, which would require utilities to conduct annual water-loss audits and publicly disclose the findings on the Internet.
The bill has already passed the state Senate and is making its way through the Assembly. Glickfeld applauds the bill. She said the audit reports will help utilities justify raising rates to fix aging, leaky infrastructure.
“Right now,” Glickfeld said, “we just don’t know what’s reasonable because we don’t really understand what the leakage rates are.”