Your most pressing water questions, answered

Clean water, like clean air, is a resource many take for granted — until there's an issue. The recent outrage in Flint, Mich., over lead-tainted water has put the topic at the front of people's minds.

So what do you know about your drinking water? Or the water that feeds the food you eat?

J. Carl Ganter, managing director and co-founder of Circle of Blue, and Dr. Deborah Swackhamer, University of Minnesota Environmental Health Sciences professor emeritus, joined MPR News editor Michael Edgerly to discuss the most pressing issues for water in Minnesota and around the globe.

"It all comes down the value of water," Ganter said. "I'm not talking about who owns water, but what are we going to use our water for: Are we going to use it to grow watermelons in the desert to ship to me in Michigan? That's a choice. Are we going to use our drinking water to flush our toilets? A lot of that water is subsidized, or the water cost is hidden, so it comes back to understanding: Where's the water come from? Where's it go? And what is its real value?"

Highlights

On bottle water vs. tap water

Bottled water "is certainly overused, and people mistakenly have the impression that bottled water is safer than tap water. In Flint, Mich., right now, yes, bottled water is probably safer than tap water," Swackhamer said.

"But it's important to appreciate that our bottled water here in the United States is managed as a beverage — it's not managed as drinking water — so it doesn't fall under the protection of the U.S. Environmental Protection Agency. It's regulated as a beverage, like Coca-Cola is regulated, by the Food and Drug Administration.

"It has far fewer tests done on the quality of water. They test for far fewer contaminates, and ... there's a great deal of byproduct, if you will: Costs in making the bottles and getting rid of those plastic bottles in recycling or landfills .... It does serve a purpose, especially in emergencies and the like, but a lot of people think it's safer than tap water and in general, that's not necessarily the case."

On nitrates pollution in water

"We definitely have nitrate problems in our water, both our surface water and our groundwater in Minnesota," said Swackhamer. "This is probably true for much of the Midwest."

"The nitrate pollution is a public health issue: It can affect small infants. It can actually kill small infants if the concentrations and exposure are high enough. It's also a problem because it's the nutrient that gets all the way down to the Gulf via the Mississippi River, and ends up causing the dead zone in the Gulf of Mexico."

"We do need to manage nitrates differently. ... In Minnesota, our goal is to reduce 45 percent of our nitrate by the year 2040, I think it is. That's an ambitious plan, but it's not trivial how we're going to do that. In fact, it will likely require major changes to how we do agriculture, how we manage water run-off, how we manage tile drainage. In some cases, it may actually change what crops are grown and where."

On how tile drainage works, and what may need to change

"Tile drainage is the removal of surface water quickly down into subsurface tiles," Swackhamer explained. "Think of them as porous pipes. It's to allow the water to drain quickly into those pipes and transport that water laterally over to a ditch or a river."

Tile drainage became popular in Minnesota beginning the 1800s because while the soil is very fertile, there were also lots of wetlands. The wetlands needed to be drained in order to make productive land for agriculture.

"They drained them by putting in tile drains," Swackhamer said. This practice continues today, though the tiles that were once clay are now plastic. "It's being used in probably almost the entire southern third of the state of Minnesota, and now we're seeing a lot of tile drainage go into the farmland along the Red River Valley."

The increased productivity came with two consequences, however. One, Swackhamer said, water now moves really quickly between the subsurface environments over to the ditch or river, "so you get lots of high water flow."

Two, "you also get lots of leaching as a result. That's where these nitrates, and to some extent the phosphorous, that's used on the fields as nutrients — they get into that tile drainage and they're whisked away into these collection points, either these ag-ditches or to rivers. That's why we have a problem of excess nitrates and phosphorus in our water: It's largely due to this accelerated transport mechanism of tile drains. They're not a bad thing per se, but they're not very well managed."

For the full discussion of water issues, use the audio player above.