DULUTH - It was 3 a.m. when Becky Haase heard the sound of running water somewhere in the house. Down in her finished basement, frigid, muddy rivers poured through the seams of the egress windows.

"It was gushing — the water was nearly knee-high when we got down there," the Piedmont neighborhood resident said.

Haase and her partner, Erik Mitchell, suffered about $50,000 in damages after Duluth's 35th water main break this year flooded their hillside home on a late February morning.

It was a day that would see another broken water pipe elsewhere in the city and came on the heels of a rash of citywide breaks, some for nearly 24 hours — and one that left an entire neighborhood without water — as crews toiled in single-digit temperatures through the night to make repairs.

It's an extremely Duluth problem and a chronic issue for the city built atop rocks and steep terrain. St. Paul, for example, repaired only a few more water main breaks than Duluth in 2021, even though it has nearly three times as many miles of pipe. This winter's deep cold Up North will probably add up to more water main breaks than usual for Duluth. Meanwhile, the city is struggling to meet its annual pipe replacement target — about 4 miles a year.

More than 400 miles of pipe stretch underground, encased in corrosive clay soil, with rock preventing some from being laid deep enough to withstand the seasonal freeze/thaw cycle. Many pipes travel uphill, and high pressure loads at the bottom can lead to cracks. Some of the heavy-walled cast-iron pipes date back to 1890, but often it's the more cheaply made midcentury pipes that cause problems.

Duluth's topography and geology give it a bigger headache than many, but plenty of Minnesota cities are grappling with the replacement of aging water infrastructure, said Elizabeth Wefel, an environmental lobbyist for the Coalition of Greater Minnesota Cities who advocates for clean water at the State Capitol.

"Most cities work on trying to replace them, but it's an expensive proposition," she said.

The Minnesota Department of Health's most recent report on drinking water said the estimated cost for the state's needs over the next 20 years is $7.5 billion, mostly in the transmission and distribution of water.

A 2017 water rate increase allowed Duluth to begin replacing 1% of water main pipes a year, a theoretical industry standard because a replacement is expected to last 100 years. But that 4.3-miles-a-year goal in Duluth hasn't yet been met, said Eric Shaffer, chief engineer of city utilities.

The cold weather and the need to replace the costlier and larger pipes under Superior Street during its recent extensive downtown reconstruction, for example, have slowed work, he said.

"We've done 2 to 3 miles in a good year," Shaffer said, replacing the cast iron with a high-density plastic.

As has been the case in Duluth, cities often rely on their own revenue to replace water mains, said Jeff Freeman, executive director of Minnesota's Public Facilities Authority, which dispenses loans and grants for infrastructure.

But at some point, he said, "it makes more sense to do a larger project, replacing larger sections," and to cities seek help from the state.

Duluth's peak for pipe breaks was in 2002, with a whopping 195. Strategic replacement of break-prone sections all but ensure the city won't reach those heights again, but 2022 breaks — 49 as of this week — will probably push past 2021's number of 103 because of the cold winter, Shaffer said.

Leaks are plentiful, too. And each break or leak costs Duluth about $8,500 to dig and repair. In 2021, that amounted to more than $1.6 million. Those repairs compete with lead remediation for money, as Duluth sets an ambitious plan to eliminate lead service lines. That is expected to cost $50 million to address and will likely benefit from federal infrastructure money on its way.

The city has project proposals for both, however, at the state and federal level.

"The city is working very hard on it, doing everything we can to pump money into the water system," Shaffer said, but another rate increase could be on the horizon.

That's not good news for Tanya Metcalf, who lives in a western Duluth mobile home park that's experienced several water main breaks this winter. It's not easy winterizing a mobile home, she said, and water shutoffs lead to frozen and sediment-filled pipes that can be hard to fix for people with limited income.

"And it's frustrating, because they continue to break and break and break every winter," Metcalf said. "How can you expect people to survive if the infrastructure we depend on isn't working correctly?"

Haase and Mitchell wonder how they'll pay for all they lost, including a brand new water heater, a washer and dryer and furnace. Their insurance won't cover the damage, so the couple filed a claim with the city.

"We did nothing wrong," Haase said, and are saddled with the expense. "It's been awful."