Burleigh McCoy

And people have documented rising chloride levels in wells across the U.S.

Michigan, New Jersey, Idaho, Arizona.

These are in rural places and urban places.

Can't the local water plant just filter the salt out?

So I talked to Kyung Do Han about this.

He goes by Do.

He's a postdoc at the University of Wisconsin-Madison studying groundwater.

And he says you can filter it out, but... It is extremely expensive.

Do told me he got into the field because when he was a kid, his family's local water source was contaminated by a nearby military base in Korea.

It started causing health issues for his family, and he remembers having rashes and sometimes vomiting until they moved and the issues went away.

So he's really passionate about keeping drinking water clean.

He is, and he's aware of how big the problem is in Madison.

This is making me realize how long salt sticks around.

Yeah.

I mean, one of my sources told me that some people in New York have to buy bottled water because their groundwater is too salty to drink.

And one family even had to sell their dairy cows because you can buy bottled water for your family, but you can't really buy it for your cows.

So the obvious way to slow or stop water from getting saltier is to use less salt.

Right.

And one person who is advocating for this is Allison Madison.

She leads a nonprofit called SaltWise, which started when people at the city and county levels in Madison started noticing salt levels going up in drinking water and wastewater.