Road Salt in Winter: Pros & Cons


A common way to clear icy roads is to apply a layer of salt, which lowers the freezing temperature of water and melts the ice. Salting roads is standard practice in several states, and many consider it an effective method for preventing weather-related collisions. In fact, the American Highway Users Alliance found that road salt reduces collisions by up to 85%.

Road salt in winter

However, road salt can cause vehicle parts to rust. What’s more, environmental studies indicate that salt from de-icing efforts can negatively affect water supplies, soil and vegetation, and local wildlife.

So, what’s the final word – is using salt to deice roads a good or bad thing? Let’s take a deeper look at the pros and cons of de-icing roads with salt.

The Negative Effects of Using Road Salt

Road Salt can damage your vehicle

Thanks to the cumulative effects of chemical reactions and time, the more road salt that comes in contact with your vehicle, the rustier it’s likely to get. Here’s how it happens:

  • Water from precipitation puts oxygen and carbon dioxide in contact with metal car parts.
  • Free-floating ions in road salt come in contact with the water. These ions speed up the formation of iron oxide.
  • Rust starts forming, since rust is simply a layer of iron oxide that appears after extensive exposure to oxygen. The addition of salt and water just makes the rusting process occur faster than normal conditions allow.

There’s no running from science, but how can you keep rust to a minimum when you have no choice but to drive on salted roads?

The best thing you can do is to wash and wax your car frequently – especially before and during winter. The more often you wash and wax, the more salt you will remove. Sealing your undercarriage helps, too. It’s often the parts of your car you don’t see that snow salt can damage the most. In the fall, before roads start getting icy, talk to a car professional about sealants and other preemptive precautions for road salt.

Road Salt may damage traffic infrastructures

Automobile owners aren't the only ones who need to worry about corrosion.  Road salt can also damage bridges, parking garages, railroads, and other public transportation infrastructures. This corrosion damage is estimated to cost the highway and automobile industries $3.5 to $7 billion per year in the U.S.

Road salt can negatively impact the environment

Think about this: just one teaspoon of salt can permanently pollute five gallons of water. Five gallons! Now think about how much snow salt appears on your roads during winter – it’s definitely more than a teaspoon. Over time, water supplies contaminated by road salt stop supporting certain types of aquatic life. This happens when salt comes in contact with the upper layers of a water source. Due to the presence of snow salt, the water becomes more dense and sinks to the bottom, preventing oxygen in the top layers from reaching the bottom layers.  This separation of upper and lower layers disrupts aquatic ecosystems. Salt can also:

  • Damage plant foliage
  • Inhibit plants’ nutrient intake
  • Kill certain plants
  • Cause salt-resistant species to proliferate, which diminishes plant diversity and further disrupts ecosystems

Even wildlife isn't immune to the impact of added road salt in the ecosystem. It impacts birds, in particular, as they are likely to ingest the salt granules. The salt can poison the birds and reduce local populations.

The Positive Effects of Using Road Salt

Salt can damage your car and pollute. But is there anything positive about snow salt?

Yes, there is. Salt’s effectiveness in preventing accidents is undeniable. For every 10% improvement in road surface friction, a 20% reduction in crashes follows, according to a study from the American Highway Users Alliance. The study also found that de-icing with road salt can reduce up to 93% of accidents – in other words, almost all of them. In addition, salt is a budget-friendly de-icer. Many states use it because it only costs about $50 a ton (though when there are shortages these prices can skyrocket to $250/ton).

The bottom line is that salt is cost-effective and prevents collisions, injuries, and highway fatalities, which is why many states still use it to melt ice on slippery roads.

Road Salt Alternatives: Alleviating Salt’s Environmental Impact

Given that road salt benefits communities by making it safer to drive in winter, what are state and local authorities doing to combat road salt’s damaging effects on the environment?

One technique growing in popularity is “anti-icing” roads in anticipation of ice’s arrival. Not to be confused with de-icing techniques, which refer to actions taken to melt ice already on the roads, anti-icing involves spraying dry roads with pre-mixed salt solutions. The result is a “non-stick” layer that helps prevent ice from forming in the first place.

Other states are exploring more unusual alternatives, such as cheese brine, molasses, and solar-powered road systems. While none of these road salt alternatives will completely replace road salt anytime soon, evidence shows they are helping reduce the amount of salt used. For example, Indiana was able to use 228,000 fewer tons of salt in a single winter thanks to anti-icing.

A Future for Snow Salt?

Road salt is here to stay.

When the weather gets bleak, preventing accidents caused by ice is a public safety imperative. Whether we address it by applying salt to icy roads or by spraying salt-based solutions on dry roads in anticipation of severe weather, salt’s effectiveness all but ensures its continued use in communities across America.

Yet researchers are still working on the development of methods that reduce overall quantities of road salt, which could mean mega benefits for our vehicles and the environment. However, a day where we are no longer reliant on salt to clear icy roadways is far off.

In summary, we are reducing our reliance on road salt. Less salt on the roads means less salt affecting our vehicles and the environment. Only time will tell if we can find a more sustainable alternative completely, but until then any progress is good progress. 

Besides waiting for road crews to salt local highways, what else can you do to stay safe on the roads in winter? Check out our list of winter driving safety tips for more ways to protect yourself and your vehicle from the effects of harsh winter weather.