How much floodwater does a car need to be damaged? Does it matter if it’s fresh or salt?

Amidst hurricanes, record-breaking rainfall, and king tides, Americans have frequently navigated their vehicles through flooded streets and puddles.

However, this constant exposure to water can take a toll on your car.

It may not be immediately apparent, but even rainwater possesses corrosive properties.

Here’s the distinction between the impact of saltwater flooding and rainwater flooding on your vehicle.

“All water can be corrosive because rainwater has acid in it, you’ve heard of acid rain,” explained Mike Porcelli, a master mechanic, automotive technology professor, and consultant. “So that can cause a lot of corrosion. And salt water is exponentially worse than fresh water.“

Porcelli goes by the moniker “M.D.” for “Machine Doctor.”

Salt attacks metal

According him, salt is highly corrosive; it aggressively targets metals, particularly materials like aluminum and magnesium. For instance, with aluminum wheels, if they come into contact with saltwater or if cars are regularly parked near the ocean, the salt can gradually erode them.

“I saw a car the other day, we opened the hood the aluminum brace (under the hood) was all corroded. And I said ‘this car must live near the ocean.’”

Even salt spray from the ocean can disperse salt particles into the air, which can travel considerable distances.

According to Porcelli, scientific literature suggests that salt particles can travel up to 60 miles in strong winds.

Furthermore, he pointed out that the side of a car parked facing the sea breeze will exhibit signs of wear and corrosion more rapidly than the opposite side, highlighting the pervasive nature of salt’s corrosive effects.

Whether you own an electric car, a traditional combustion engine vehicle, or a hybrid, saltwater poses a threat to all types of automobiles,” cautioned Lauren Fix, The Car Coach, during an interview with FOX Weather. “what it does is it rots out things you don’t think about, like the exhaust system, brake lines and fuel lines.”

She held up two brake lines for emphasis, one shining silver and clean, and the other originating from a car in Naples, Florida, which had recently endured the impact of Hurricane Idalia and was subsequently battered by Hurricane Ian.

Fix pointed out that the rust and corrosion can occur surprisingly quickly, highlighting the urgency of addressing these issues to prevent extensive damage.

These line failures can impair brake function and lead to fuel leaks instead of the proper flow from the gas tank to the engine, creating safety risks.

Flooding can be catastrophic for electric vehicles

“Also, electric vehicles, saltwater is very, very corrosive. If you have an electric vehicle that has been in a flood. Do not drive it, absolutely. Don’t even try to start it,” Fix said. “Contact your insurance agent and let them pick it up. Take it to your local shop, see what they can do.”

After the floodwaters from Hurricane Idalia receded, several electric vehicles caught fire.

Acid dissolved in rain water damages paint

Salt air and fresh rainwater both contribute to the erosion of the paint. According to him, saltwater also possesses acidic properties.

“It eats into the paint surface. After a rainstorm, you see the water bead up on the car and then after it dries, it leaves a little ring, Porcelli said. “And the acid will eat, it will onto the paint. And the only way to remove that is to remove some of the paint, cut down below the craters that are created by the acid.”

However, corrosion isn’t the only concern when it comes to water infiltrating your vehicle. Accumulated water fosters the growth of mold and mildew.

“If it (water) penetrates inside (the car) then it’s going to need professional help,” Porcelli recommends. “Even if it’s just to take the rugs out and dry them, disinfectant them and put it all back together.” 

He mentioned that the process of steam cleaning, drying, and disinfecting a car should cost approximately $1,000 if addressed promptly.

Once mold and mildew have taken hold, you may find yourself needing to replace the rugs and carpets. Additionally, the foam within the seats can also become moldy and deteriorate.

Electronics and water don’t mix

The primary concern with modern cars and flooding, he emphasized, is the vulnerability of the electronic components.

“Everything is controlled by computers. The power windows are controlled by a computer. The lights are controlled by computers. So every electronic system from the engine to the transmission, tail lights, even the radio is controlled by computers” Porcelli said. “Some of those computers are down under the seats or up under the dashboard, down low. If water gets into the car and floods the floor of the car, those computers are subject to getting waterlogged.”

He explained that this is precisely why most insurance companies often declare cars as total losses in the event of flooding, even when there is no apparent visible damage.

Driving on roads treated with salt during snowy and icy conditions can be equally detrimental to your vehicle.

Snow can become compacted in the crevices and spaces underneath a car, while salt residue tends to persist even after the snow has melted.