One of the most difficult things about winter can be driving in the snow and ice. So it may seem like road salt is a driver’s best friend. However, road salt can pose a serious problem for the environment, and for homes.

Bob Davis’ home in Boxford looks like it’s in the middle of the country. But as he stands on his front lawn, there’s one constant reminder of civilization.

“Can you hear how close we are to the highway?”

You can’t see it, but the hum of nearby I–95 is ever-present. The highway wasn’t a big concern until they put the house on the market about 11 years ago. They had a prospective buyer.

“And the home inspector told the people not to buy the house because the sodium levels were so high in the water that everything in the house that came in contact with the water was going to start corroding and falling apart.”

Davis’ family had noticed the tap water water was a little salty. But after the sale fell through, that inspector’s predictions started coming true.

“This is where the bathroom used to be.”

Davis walks into a small empty room on the first floor with stripped walls. It’s been like this since all the pipes corroded. The salt also ate through their furnace and water tank. Looking for answers, Davis talked with an expert from the University of Maine.

“He asked me what the chemical makeup was from the test that I had. I told him and he said ‘it’s road salt.’”

In addition to runoff from nearby I–95, the state was storing a massive pile of road salt right at the end of his street. There’s no municipal water system in Boxford. Each home has its own well. The state tried to fix more than two dozen contaminated wells in Boxford. But some, like Davis, couldn’t be fixed. After the town filed a lawsuit, the courts ordered the Boxford salt depot shut down in 2008, and the state agreed to make improvements to the I–95 drainage system there.

The thing about salt that makes it great for melting snow and ice is the same thing that makes it a likely contaminant.

The thing about salt that makes it great for melting snow and ice is the same thing that makes it a likely contaminant. Thomas Ballestero is the director of University of New Hampshire Storm Water Center.

“We use the chloride, the road salt because it readily dissolves and therefore lowers the freezing temperature of water so you don’t’ have ice any more. Once its dissolved its nearly impossible to get out by simple means.”

Rafael Mares of the Conservation Law Foundation says that chloride can be bad for the ecosystem.

“And if you’re an animal, lets say a fish, and you’re used to a certain level of salinity in your pond, and you’re used to fresh water and suddenly it becomes salty, that can also be a problem.”

State records from last year showed chloride contamination in six rivers and streams around the state. And Boxford isn’t the only place to see contamination of drinking water. A state remediation team responded to 60 cases of salt contamination between 2010 and 2015.

“This is about 55 hundred tons of salt.”

Scott Wilson, the state Director of Roadway Operations stands in front of a massive salt pile in Milton, which is covered with a huge shed. Wilson says the state’s 150 salt depots like this are now covered to prevent runoff.

“It solves a big problem around our depots, where we would have open piles and obviously any time it rained it would run off and it would go in all directions.”

There are alternative substances that can be used to melt snow and ice, but salt is by far the most economical. To use salt more smartly, the state’s now using sensors that measure the grip of the roadway and the road temperature, since salt doesn’t work when it’s below 20 degrees.

“We also pre-treat roadways, where we use liquid deicer which stops snow and ice from bonding to the pavement, which allows us to use less salt during the event and less salt in terms of cleanup.”

Contamination is a concern, he says, and they do their best to clean it up when it happens. But Wilson says there is a balance that needs to be struck.

“Obviously we have no intention of contaminating a well or causing elevated chlorides in anything. But we do have a responsibility of making sure that the public is safe and we clear the roads in an efficient manner.”

And he says by carefully managing how they store and use road salt, they can keep roads safe, while at the same time prevent contamination of wells and waterways.