Minnesota communities will need almost $5 billion to fix aging sewer systems in the next 20 years, according to a state survey.

The Minnesota Pollution Control Agency surveys communities every two years about wastewater infrastructure repair needs, Minnesota Public Radio reported . The 2017 survey was reported to the Legislature on Jan 15. It estimates a 15 percent increase from the 2015 survey, which projected a $4.2 billion need.

Only 5 percent of the costs are related to meeting higher water quality regulations, said Cara Omana, an environmental specialist with the agency. Most of the funds are to fix aging or inadequate pipes and pumping systems, Omana said.

"Much of Minnesota's wastewater infrastructure was built in the '70s and '80s, so at this point a lot of it is getting older and needs to be replaced," Omana said. Wastewater treatment plants that are more than 40 years old are past their expected useful life.

Many small cities across the state are struggling to find money to cover the costly repairs. The survey found that about 20 percent of cities with fewer than 1,500 residents reported being unable to afford wastewater costs.

Gov. Mark Dayton has asked for $167 million in his water infrastructure bonding proposal, some of which would be used to help communities pay for improvements.