As Cambridge copes with a critical drought, the city’s water department has made significant progress reducing leaks and other sources of wasted water. Yet hundreds of millions of gallons are drained every year and it’s impossible to eliminate the loss.
“In a city like Cambridge some water mains are over 100 years old,” water department managing director Mark Gallagher said. “There’s a lot of utilities in the ground. It’s hard to find everything.”
Add to that the problem of timing. A leak could start the day after leak detection workers inspected the pipe, Gallagher said. Or leaks could be undetectable because “they’re underground and go into a drain and we never see them,” he said.
State and federal agencies recommend that public water systems strive to keep water loss, called “unaccounted-for water,” to 10 percent of total water supply. “We’re on the cusp of that,” Gallagher said.
From 2018 to 2023 the figure varied widely. The city lost 642 million gallons – 14.8 percent — in 2020 and 828 million gallons, or 18.4 percent, in 2021. Gallagher said pipes weren’t inspected during the pandemic because of lack of staff. More recent losses were closer to 10 percent: 480.5 million gallons, or 10.3 percent in 2022 and 513.2 million gallons – 11 percent – last year.
The city’s performance is far from the worst in the state. Malden’s loss hovered at more than 25 percent between 2018 and last year, for example, while Brockton hit 32 percent in 2021 and 50 percent last year. Some systems have done better than Cambridge. Notably, Boston’s loss ranged from 7 percent in 2018 to 9 percent last year.
Public water systems throughout the state file an extensive report every year that includes the amount and percentage of unaccounted-for water. They calculate the number by starting with the total amount of water available for distribution, then deducting the amount that passed through water meters. That result gives a figure for unmetered water. Then water systems can reduce that amount by subtracting an estimate of unmetered water used for municipal purposes, such as hydrant flushing. The final figure represents unaccounted-for water, essentially the water supply that was wasted.
Cambridge’s performance has improved a lot, though the figure can vary widely from year to year, “Years ago we were at 17 percent,” Gallagher said.
Leaks get fixed fast
To reduce wasted water, the city hires an outside company to look for leaks in the entire water system every year instead of performing the work every two years as the state allows, he said. “It takes two and a half months to do a complete check. They literally walk down every street,” Gallagher said.
Then leaks get fixed quickly. “Any water loss is important,” Gallagher said. “As soon as we discover a leak we typically are out there fixing it the same day.”
“Being in a drought you think about it and worry about it,” Gallagher said.
The city is also working to upgrade ancient water mains, he said. And it has installed water meters to keep track of uses such as irrigating athletic fields so that the estimate of municipal use is more accurate, he said.
Meanwhile, demand for water increased in 2022 after a dip during the pandemic, and dropped slightly last year, though it was still higher than in 2019 before the pandemic, according to annual reports filed with the state. Gallagher said a consultant hired by the department says the city will have enough water into 2050, even with higher demand and expected droughts.
Backup can meet demand
During a severe drought in 2016 the city got water from the Massachusetts Water Resources Authority. The city also tapped into authority supplies in 2019 and 2022, the latter instance because of worries about increasing amounts of the forever chemical PFAS in city water, not because of low supply.
Speaking of the MWRA, Gallagher said: “We have backup that can meet 100 percent of our demand.” When most of the state went into critical drought last month, the authority’s Quabbin Reservoir “was still at 86 percent [of capacity],” he said. Cambridge? “We’re now at about 32 percent,” he said.
Cambridge could turn to the MWRA before long; at a meeting of the city’s water board Nov. 12, Gallagher said it would be necessary unless there is “significant rain in the next 30 days.” Last week he said he’s optimistic.
“In November there was above-average rainfall,” Gallagher said. “We’re seeing more normal precipitation patterns developing. I’m hopeful that will continue.”
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