All too often, these vehicles make their way onto used car lots, or are offered in the classifieds in private party sales. A new report from Carfax, an automotive data company, suggests consumers are currently driving around in 325,000 cars and trucks that have been underwater.
That's a 20% increase over last year and doesn't take into account the impact from the recent hurricanes.
In most cases, when a car is submerged in water, the insurance company will declare it a total loss, and write the owner a check for a replacement. But that doesn't always happen.
What to do if your car is flooded
State Farm Insurance advises consumers whose cars have suffered flood damage to carefully inspect the vehicle, but not to start it. If water has gotten into the engine, starting it can cause even worse damage.
The company offers a step by step guide here.
As you might expect, it all depends on how high the water got. If it covered the floorboards but didn't make it to the seats, there might be extensive damage but the insurance company might decide it can be repaired.
The experts at Popular Mechanics suggest wasting no time cleaning out your flooded car, since mold, mildew, and even corrosion can set in almost immediately. They say you need to get started before the insurance adjuster arrives, because there is no guarantee he or she can get there right away, especially if there has been widespread flooding.
If the water has made it all the way to the dashboard, the vehicle needs to be totaled. That's especially true if the flooding was caused by salt water. Maybe the interior can be cleaned and the mechanical systems repaired, but Popular Mechanics says the complex and intricate electrical systems in today's vehicles are probably beyond repair if they were submerged.
What buyers should watch out for
So consumers shopping for a used car have to be aware of two types of flooded cars; those that have been repaired but may still have flood-related issues, and those that should have been junked but somehow have made it back onto the market.
There are classic signs that a car has been underwater. When you open the door, you are likely to be greeted by a musty odor, no matter how much detergent and disinfectant was used to clean the interior.
This will be especially true if you open the trunk. The trunk compartment is not ventilated and it is almost impossible to cover up that musty smell.
You might also be able to see signs of water damage. If the car was underwater for any period of time, there may be a watermark on the seats that is difficult, if not impossible, to remove. It might be even more visible in the trunk.
Look for signs of rust on metal fixtures, especially seat belts, and look at the rear of the car for the dealer decal. If the dealer is in a market -- like Houston -- that recently suffered flooding, the integrity of the vehicle needs further investigating, especially if it is on a used car lot in Illinois.
The reason consumers should avoid flooded cars goes far beyond cosmetics. A flood-damaged vehicle is probably going to be an unreliable vehicle. One thing after another may go wrong because the vehicle may be rusting from the inside.
'Salvage' title
If an insurance company declares a flooded car a total loss, there is nothing to prevent you from purchasing it from the insurance company and trying to repair it. But if you do, that vehicle, by law, must carry a "salvage" title. That lets any potential buyer know that the vehicle has been repaired from a defect serious enough to deem it a total loss.
"Our data shows there's still much work to be done in helping consumers avoid buying flood damaged cars," said Dick Raines, president of Carfax. "They can, and do, show up all over the country, whether it be a few miles or hundreds of miles from where the flooding occurred."
Raines worries about what Hurricanes Harvey and Irma will mean for unsuspecting consumers shopping for a used car. He estimates the two storms could result in several hundred thousand more flooded cars ending up on used car lots and in the classifieds.
"Buyer beware" has never been more important than now when you go used car shopping.