Oversalting is bad for the environment: What's the right amount for sidewalks and driveways?

How much salt is really needed for de-icing?

As it turns out, you probably don't need to use as much rock salt to melt ice on your property -- and overuse is having some ill effects on the environment.

(FOX 9) - The Minnesota Pollution Control Agency (MPCA) is once again warning homeowners not to overdo it when it comes to salting their driveways and sidewalks during the winter. When it comes to salt, they say, a little goes a long way.

Why is salt bad for the environment?

What we know:

When the snow melts, or it rains, the salt runs into storm drains and into nearby lakes, rivers, streams and the groundwater. That puts unhealthy amounts of sodium chloride into fresh water sources. The salt is also toxic to fish and plants.

Salt can also accelerate the breakdown of concrete, asphalt and brick. The salt also isn't good for our pets' paws or if they happen to ingest the salt.

How much salt to use for driveways, sidewalks?

By the numbers:

The MPCA says a little rock salt can go a long way for de-icing. The agency suggests that about a coffee mug's worth of salt is enough to cover a 20-foot driveway or ten sidewalk squares (about 1,000 square feet).

As always, the more snow you can remove before you put down salt, the better. And, if you notice leftover salt on a sidewalk, you should probably use less next time around. Leftover salt on dry areas can be swept up and reused and only salt necessary areas.

It's also important to remember that when temperatures get too cold, below 15 degrees, salt isn't effective at de-icing.

Salt alternatives

The other side:

There are a lot of suggestions for salt alternatives on the internet. Some people suggest using Epsom salt instead of ice melt. Epsom salt, magnesium sulfate, is less harmful for the environment and also effective at melting ice. But, it works slower, and it isn't effective once temps drop below 20 degrees – which is an issue in Minnesota. It is also significantly more expensive than rock salt.

Others suggest using sand instead, which helps provide more traction on sidewalks but doesn't necessarily help with melting ice or preventing ice. Some people suggest heating up the sand before using it to help with melting. Ecowatch.com, an environmental news site, suggests using old coffee grounds, sugar beet juice, unused pickle juice brine, or alfalfa meal.

Another alternative is to make your own brine. While this still uses rock salt, you end up using less salt than hand spreading. You can make your own brine at home by taking rock salt and mixing it with hot tap water (3.5 cups of rock salt per gallon of water) and stir until the salt is fully dissolved. Then pour the mixture into a garden sprayer and apply in a zig-zag pattern over sidewalks or driveways.