Walk through a park or a golf course in the future and you may see your former toilet water at work.

State and regional officials are looking for ways to squeeze more out of the water that spins down our drains, following the lead of drought-ridden states that have pioneered the reuse of wastewater. It could have another life cooling industrial plants, irrigating crops, watering golf courses, flushing toilets or, perhaps one day, replenishing the drinking water supply.

Some of those things are already happening on a small scale in Minnesota, where plentiful water hasn't historically made reuse a big priority. But state and regional officials are thinking about the future.

"It's way easier to start the conversation now than to wait until wells start running out," said Jon Eaton, Eagan's utility superintendent.

The state's largest wastewater treatment agency, the Metropolitan Council, is mulling how to respond to a request from a Canadian firm that wants specially treated wastewater to cool an ethanol plant. Mankato already uses treated wastewater to cool a power plant, sweep the streets and water new trees. Several golf courses irrigate with treated wastewater. The small city of South Haven in Wright County, population 190, uses treated wastewater to irrigate a cornfield. The corn is fed to cows.

"We figured, what the heck, why don't we just do it like this and use it for a useful purpose before it goes anyplace else?" said Dan Dawson, the city's water operator.

By contrast, the bulk of the metro area's wastewater now ends up in the Mississippi River. The Met Council treats nearly enough water every day to fill Lake of the Isles, and the resulting product is cleaner than the rivers it enters. But it would require extra treatment for reuse.

Wastewater is highly regulated due to the potential public health risks, but Minnesota lacks a comprehensive policy to guide the web of agencies with jurisdiction over its reuse. Interest in the topic prompted the Legislature in 2015 to direct state officials to explore the creation of a state water reuse policy.

The group is looking at both large-scale and in-home applications. For instance, while some Californians have systems that reuse laundry water for home irrigation, that is barred under Minnesota's plumbing code without a special exemption.

'Underused resource'

About 82 percent of wastewater reuse in the United States occurs in Florida, Texas, California and Arizona, according to Bluefield Research, a Boston-based market research firm. Most of it is for irrigation, though the firm expects more industrial and drinking water applications in the future. And reuse is expanding beyond states with water shortages.

"When we started out looking at California, it was in response to a very immediate, drought-driven need," said Erin Bonney Casey, Bluefield research director. "But increasingly communities are looking at it as a long-term water supply strategy."

Former Minnesota Sen. Mike Jungbauer, who once designed water systems, said he routinely introduced a bill at the Legislature to establish recycled water guidelines similar to California's but met resistance from state agencies.

"We're 30 years behind California, but we're probably 10 years behind the curve on most other states," said Jungbauer, a Republican who represented East Bethel and left the Legislature in 2012.

Though rainwater reuse has emerged in Minnesota — both Target Field and CHS Field capture rainwater for reuse — recycling wastewater is less prevalent. But it is happening on a limited basis.

The largest example is in Mankato. A decade ago, Calpine Corp. paid $22 million to build the city a special facility that applies extra treatment to the city's wastewater so it could be used to cool a new power plant. The resulting system sends millions of gallons a day to the Mankato Energy Center, while the city also uses the water to irrigate parks, sweep the streets and grow trees.

"It's very interesting. And it's an underused resource across the country," said Mary Fralish, who recently retired as Mankato's public works director.

In the south metro, the Shakopee Mdewakanton Sioux Community (SMSC) sends its treated wastewater into a wetland connected to a pond used for irrigation around the reservation — including a golf course. But the tribe also spent five years studying how to treat wastewater thoroughly enough so it could be injected back into the groundwater aquifer, replenishing the drinking water supply.

The resulting water was so clean they had to add chemicals to it to match the aquifer, said Stan Ellison, SMSC's director of land and natural resources. Implementation is on hold until a future expansion of the tribe's wastewater plant. State law generally bars injecting water directly into groundwater aquifers, but as a reservation, the tribe would have to seek permits from the Environmental Protection Agency.

The concern with such a setup is generally a psychological one, Ellison said.

"As a scientist, I can tell you that's 99 percent of the problem," Ellison said. "Because there's no issue with direct reuse other than the ick factor."

More study needed

Wastewater hasn't been treated and reused as drinking water in Minnesota. The Met Council isn't considering it at this time, focusing instead on non-potable applications like cooling and irrigation. But others are looking into what it might require.

"There would need to be treatment standards, water-quality requirements and operator requirements, as well as an understanding of how this process would work with Minnesota's geology and water chemistry," said Anita Anderson, a principal engineer at the Minnesota Department of Health.

Reusing wastewater comes with extra costs, too, from additional treatment expenses to special piping.

Some utilities around the country charge users full cost for reused wastewater, but others give it away for free, said Deborah Manning, principal engineer at the Met Council's environmental services division.

The issue may grow more attractive if our water appears less secure.

"In Minnesota, [we're] still thought of as a relatively water-rich state," said Randy Thorson, a principal engineer at the Minnesota Pollution Control Agency. "As things change in the future, that could cause us to look even more closely at these things."

Eric Roper • 612-673-1732 Twitter: @StribRoper