To get the water and sewer pipes up to date in Little Falls, Minn., it'd take about $7 million a year — money the city does not have.

But the town's underground infrastructure is aging, said city administrator Jon Radermacher. Much of it is more than 40 years old — the oldest portions were installed 80 years ago — and replacing those pipes is costly.

So, Little Falls officials have to focus on areas where water mains have been breaking and trying to get those repaired first. But when and where those breaks will occur isn't easy to predict.

The Water Main: Making sense of the complex world of water

"It's always something that's kind of looming for us of not if but when those are going to occur," Radermacher said. "It's just knowing the condition of those pipes in the ground, it's going to happen at some point."

Aging underground infrastructure problems are widespread in greater Minnesota. Water and sewer pipes are reaching the end of their expected life spans in many places, and there's not enough state or federal funding to meet the needs — especially for small cities.

"I think we are on the verge of what could be a crisis," said Elizabeth Wefel, a lobbyist for the Coalition of Greater Minnesota Cities. "When you start seeing all of these facilities across the state starting to hit a certain age and the funding isn't keeping up to help rehabilitate or build new, we are going to be facing a crisis."

Jeff Freeman, executive director of the Minnesota Public Facilities Authority, said many Minnesota towns outside the Twin Cities metro area have water treatment plants 30 or 40 years old, and pipes that date back to the Great Depression.

It's tough for small cities to take on the major costs of replacing them, he said, so they often wait until it's necessary.

"Ultimately, it comes to the residents to pay those costs," he said. "And that's why smaller cities in particular have difficulty because they just don't have the user base to spread the costs over that bigger cities have."

Motorists got a taste of what can go wrong when a pipe bursts on Sunday when a water main burst in Oakdale, Minn., causing a sinkhole and likely days of traffic headaches.

The Water Main MPR

The Oakdale water main was installed in 1964, so city officials say they don't believe age was a factor in the break. But many cities across Minnesota have drinking water and sewer pipes much older than that.

Cities can get low-interest loans and some grants from the Minnesota Public Facilities Authority to help cover the cost of replacing aging water and sewer systems. But that money only goes so far. And there's a big gap between cities' needs and how much funding is available.

Freeman said his agency finances about $150 to $200 million a year, which covers about 30 to 40 city projects.

But state officials estimate the need for drinking water and wastewater improvements is about $11 billion over the next two decades.

Last year, DFL Gov. Mark Dayton proposed a hefty spending bump for cities to replace aging water systems. The Legislature did approve additional bonding money, but it wasn't the full amount Dayton requested.

While the extra funding helped, Wefel said, cities need more. While state lawmakers are starting to grasp the seriousness of the problem, she said it doesn't get as much attention as crumbling roads and bridges.

She thinks that has to do with one simple fact: the problems are hidden underground.

"Until you have something like a sinkhole, you don't see the pipes falling apart," she said, "you don't see that there are challenges in the water. It's not as visible."

Tim Nelson contributed to this report.