Washington Suburban Sanitary Commission crews prepare to install a new water main. Zinc coating takes the hit of corrosion before it reaches the iron pipe, while a thick, plastic “bio-wrap” wards off the tiny microbes in soil that also speed deterioration. (Katherine Shaver/The Washington Post)

Maryland’s largest water utility says it’s among the first in the country to begin installing a new kind of water main with a protective wrap that is designed to withstand breaks for a century or more, compared with the 50 to 75 years its current pipes typically last.

The Washington Suburban Sanitary Commission said the new pipes are made of ductile iron, like many of its current mains, but have an additional zinc coating and a thick plastic “bio-wrap” that ward off corrosion.

WSSC officials say the Washington suburbs will still see hundreds of water main breaks this year, particularly when the region’s topsy-turvy winter weather taxes them.

But as broken and aging mains are gradually replaced with the more corrosion-resistant pipes, utility officials say, future generations should see fewer breaks snarling their traffic, flooding their homes and cutting off their water during repairs. Their streets also will be dug up less often for pipes to be replaced.

“We won’t be back here for 100 years,” Gary Gumm, WSSC’s chief engineer, said Thursday as crews installed a new pipe to replace a 90-year-old main in Bethesda’s Brookmont neighborhood.

A Montgomery County police patrol car splashes along Grandview Avenue in Wheaton, Md., on July 1, 2015, after Georgia Avenue was closed because of a water main break at Weisman Road. The pipe was 68 years old, WSSC said. (Michael S. Williamson/The Washington Post)

Like other water and sewer utilities across the country, WSSC has struggled to replace its underground pipes as many reach their life expectancy after years of neglected maintenance. WSSC, which provides water and sewer services to about 1.8 million people in Montgomery and Prince George’s counties, averages nearly 2,000 water pipe breaks annually. Although the number fluctuates from year to year, the overall trend is up, Gumm said.

[WSSC looks to its own gunked-up pipes for partial cause of brown water]

With money from its customers’ steadily rising rates and a new infrastructure fee, WSSC has stepped up its pipe maintenance in recent years and now annually replaces about 60 miles out of the 5,800-mile system. Nearly 40 percent of the system is more than 50 years old, and some pipes in older suburbs, particularly near the District line, hover around the century mark.

Gumm said the zinc coating takes the hit of corrosion before it reaches the iron pipe, while the thick, plastic “bio-wrap” wards off the tiny microbes in soil that also cause pipes to deteriorate. He said he believes that WSSC is the first U.S. water utility to require both. Zinc-coated pipes have been used in Europe since the 1950s, and U.S. utilities have used a different kind of plastic wrap since the 1990s, industry officials said.

Allen H. Cox, regional director of the Ductile Iron Pipe Research Association, called WSSC’s twofold approach “unbelievably forward-thinking.” Cox said research has shown that such pipes, if installed properly and not disturbed by other digging, last well beyond 100 years.

“This is the most aggressive means of corrosion control,” Cox said.

[Why Maryland has some of the most problematic water pipes in the U.S. ]

Gumm said the new pipes cost a bit more, but because their installation costs are about the same, the overall $1.6 million per mile in replacement costs rises to about $1.62 million. However, he said, the new pipes should “more than pay for themselves” when they result in long-term savings from needing to be replaced less often.