Driving Through Water

The Thrill

It might seem like a lot of fun to drive your vehicle through water, but unless your vehicle is set up to go through water, you could run in to some serious problems.  Today, we will look at why it is dangerous, and hazardous to your car to go through water that is more than a few inches deep.

How Deep?

Photo by Jon Flobrant on Unsplash

First off, your car was probably not designed to go through deep water.  For the sake of this article, let’s just define “deep water” as anything that goes up to the bottom of your door. You will understand more about why I said this in a minute. So the real problem here is kind of obvious.  If it is a rainy day and you come up to a flooded street, how do you know how deep the water is? There could be pot holes or deep areas that could literally ruin your car, or even a truck, if the unseen threats beneath the water are big enough. Not knowing the depth of the water is your first issue.

Rushing Water

Next, if the water is rushing or moving at all, stay away! All you have to do is search your favorite online video sharing website for floods and cars. You will no doubt see cars being lifted up (since the gain some buoyance) and dragged down the rapids. Floods with rushing water are therefore extremely dangerous.  Do not ever try to cross a stream or any rushing water.

Now, you are probably saying, “But I have a Jeep (or other off-road vehicle).” Well, that is great, but you still have to be careful and take proper precautions.  Not all “off-road” vehicles are set up properly to go through water. In fact, even many so-called “off-road” vehicle manufacturers warn against going through significant amounts of water (rightfully so). But why is it so bad for your car? After all, you drive through the rain. Surely the underside of the car can get wet. Well, sort of.

Water in the Transmission

One the main parts of a car that can get ruined when going through deep water is the transmission. Most transmissions have a vent that allows the air pressure inside the transmission to be the same as the outside.  It is not used for cooling, but for maintaining barometric pressure. Going through a deep puddle can easily allow water to enter the vent and get inside your transmission.  When that happens, your transmission fluid turns into a milky foam.  Usually, it requires a full transmission rebuild, or a new transmission, depending on the damage.  And, here is the sad part, it only takes about an ounce or so of water to wreak your transmission.  So, why can some vehicles go through really deep water? Answer: Snorkels.

Just like a person uses a snorkel to breath under water, a vehicle can be equipped with snorkels to allow the vehicle to “breathe.” Usually, the undercarriage is protected and the air and exhausts, as well as the transmission, all vent through snorkels to protect the vehicle. Even then you still need to be careful.


So, unless your car is sporting the right gear (snorkels, etc.), the best thing to do is stay away from deep water, or water that is of an unknown depth. You will save your car and a lot of money too.

Written by Gary Pradel