Home Diagnosis and TroubleshootingClimate Control and Air Conditioning Water Dripping From Car: How To Deal With This

Water Dripping From Car: How To Deal With This

by Jordan Harris
Water Dripping From Car

Water dripping from a car is more than a nuisance. It can cause damages to the vehicle itself. Most of the time, water causes mildew and mold to form on and under carpets. This causes rust to the floor pan and other metal components. If water drips into the electrical system, it can cause serious short-circuits and other damages that are difficult to find and repair. Electrical issues can be very costly to repair and diagnose.

Unfortunately, water leaks can be very hard to find. Often, the place where the water shows up inside of the car is far from the place where the water is entering from. Sometimes, the two locations can be a couple of feet apart. Water can enter the vehicle and travel through a channel in the body or interior trim before reaching the place where it shows up.

Contents of this article entail;

The Difference Between Coolant Leaks And Water Dripping From Car

If you see water dripping from your car, the first thing you need to do is verify where exactly it comes from. Although water dripping from your car isn’t something you usually have to worry about, the presence of coolant, or other fluids, can show a serious problem.

Depending on where you park your car, it may be quite easy, or very difficult, to tell what, exactly, you’re looking at. Coolant and water can look very similar on a dark, uneven surface, like an asphalt driveway or parking lot. You may touch the fluid with a finger to tell whether it’s oily, but it can be harder to discern whether it’s coolant or plain old water.

The easiest ways to tell the difference between coolant and water are the smell and the color of the fluid. Water is odorless, while antifreeze has a sweet smell. So if the fluid under your car smells sweet, it’s probably coolant.

If you place a drop cloth, paper, cardboard, or a pan where the liquid is dripping from, you should be able to collect enough to determine the color. If it’s colorless, then it’s just water, while green, yellow, or blue fluids could be antifreeze.

The only time actual water will drip from your cooling system is if someone placed water, instead of a mixture of water and antifreeze, in the cooling system. This is unlikely since there aren’t any circumstances where straight water would be used like this, but it’s still worth checking. If you draw some antifreeze from your radiator, and it looks like straight water that is a problem.

First Step: Diagnosing Water Dripping From Car

As with any sort of troubleshooting, a lot of the process for finding a leak is a mindset. It is necessary to start by looking at where the leak is and when it shows up. Finding the source of water dripping in your car isn’t hard. It usually collects in the lowest spot. But diagnosing where it came from is notoriously hard.

Water obeys the laws of gravity, so will always pool in the lowest area. But it can run along wires, travel up cardboard and fabric surfaces, and generally do its best to disguise where it came from in the first place.

Water leaks typically leave some sort of telltale marks. Wet carpeting or upholstery is obvious but not all leaks are obvious. Many leaks cause water stains (it helps to learn how to get water stains out of car seats) which are mineral deposits left behind by the water when it evaporates. Another key indicator is rust on the inside of the vehicle. Rust will not form unless the inside of the vehicle has been getting wet.

The first clue to help find the leak is knowing when it happens. Is it after a rainstorm or a car wash? Only when the car is parked on a slope? Was it just after using the heater or defroster for the first time in a long time? Or maybe the AC? Figure out if the car has to be moving or making a turn for it to leak. You can as well figure out when the car started leaking. Identifying when might narrow down where and when.

If it leaks even when it hasn’t rained or the car hasn’t been washed, then it’s coming from somewhere within the car itself. If it only happens when the car is parked on a slope, it’s probably a failed weather-stripping seal or blocked sunroof drain.

Common Causes Of Leaks And Water Dripping From Car

Water dripping from a car can be caused by many factors. Some of them involve normal wear and tear of the vehicle. Others can be because of poor collision repairs, a poorly installed aftermarket windshield, or the addition of aftermarket accessories cause others.


If the car’s windshield was just recently replaced, chances are that it is the culprit. A proper windshield replacement requires complete removal and replacement of all the old urethane.

If not enough of the urethane is used or the old urethane was not fully removed, the windshield may not seal properly. Since the urethane takes some time to dry, the vehicle should not be driven for several hours after the new windshield is installed. If it is driven, it can cause the seal to fail or worse cause your airbags not to function properly in case of an accident.

Never use silicone to seal a leaky windshield. This will prevent the correct sealant from adhering properly, should the windshield be replaced in the future.

Weather Strips

The second most likely area for a car to leak is at the door seals, especially in older cars. While the style of door seals can vary considerably, they are all foam rubber, which has a sealed surface. When the door is closed, this seal is compressed between the door and the door frame, making a secure seal.

Age and heat affect any rubber part and speed up this process. Thus, in tropical climates, the deterioration of door seals is quicker than in cooler climates. As the rubber ages, it dries, shrinks, and can crack. It is not uncommon for door seals to become torn when putting large objects into the car.

Another problem that can affect door sealing is accidents. Some accidents cause the vehicle’s body and frame to warp. Body shops try to make the car look new again. In doing so, they may not deal with this warping.

Instead of straightening parts (which may be impossible), they may shim them to look right. However, this can leave a gap in the door seal that is not visible. Door seals can be replaced. The seal must be properly aligned.

Body Seams

Any place where two-body panels come together is a prime place for water dripping from the car. When these seams are low down on the vehicle, they usually are not a cause for concern. However, when they are on the roof or near the rear trunk, they can cause major leaks. When these seams leak, the entry point for the water can be as far as a couple of feet away from where you notice the water.

Body seams can leak if they were not properly sealed at the factory. They can also open up from an accident or hitting potholes because of colder temperatures thus breaking their original seal. This would typically be a small leak that is very hard to find.

The biggest problem with finding these leaks, besides the fact that the water exits at a different place from where it enters, is that the sealant in the seam makes it look like there should not be a leak.

This type of leak requires that the old sealant be removed and the new sealant be put in its place. Silicone sealant should not be used; as it will prevent paint from sticking, it can also cause rust as silicone contains acetic acid. There is a special body seam sealer available that is designed specifically for this purpose.


Sunroofs are a common area for leaks. If the seal around the sunroof becomes damaged, water will enter, especially when driving through rain or car washes. OEM sunroofs are designed and manufactured with a “pan” around the perimeter of the sunroof to catch any water that tries to enter.

There are drain tubes in the four corners of this pan. The drain tubes allow excess water to drain out of the vehicle usually behind the dash or out by the wheel wells.

These tubes can become disconnected or blocked with debris. Should a tube become disconnected or blocked, it is fairly easy to repair it. Blockage can be cleared out by shoving a piece of weed eater line through it.

Care must be taken to avoid puncturing the tubing when doing so. Tubes that have slipped off the fitting can be reinstalled. If this is the case, be sure to attach the tube with a small hose clamp to help prevent it from falling off again.


If the leak begins shortly after the installation of an aftermarket accessory on the exterior of the vehicle, there is a high probability that the installation caused the leak. Aftermarket sunroofs, moon roofs, and luggage racks all require drilling holes in the vehicle’s roof. If these holes are not properly sealed, water can seep in through them.

Sunroofs and moon roofs should come with rubber gaskets to put under their flange during installation. The operable part should have an adequate rubber seal to seal it against the frame. However, some lower-cost units may not have sufficiently well-designed seals. In these cases, the addition of self-adhesive foam weather stripping may help.

Roof racks do not always come with any sort of rubber seal to go under them. However, the mounting holes must be sealed. If there is no seal provided, they can be sealed with caulking. Pure silicone caulk should not be used, but a silicone mix can be. An alternative way to seal them is to cut a rubber seal out of sheet rubber or an old inner tube.

Aftermarket remote start or wiring could also be an issue if not done properly. Sometimes holes are drilled to run wires, and the hole is not properly sealed or a drip loop not installed in the wire.


Some models of cars tend to rust above the windshield and back window. Even if the roof is not visibly rusted all the way through, it may have rusted enough to allow water to seep through.

To accommodate this type of repair, the glass will have to be removed. It is necessary to remove as much of the rust as possible and then stabilize the remaining metal so that it will not rust. A phosphate solution is good for stabilizing rusted steel.

Once that is done, body filler can be used to fill in the rust and skim over the area. The area must then be sanded smooth and repainted. This is a job for a body repair professional.

Water Leaking From The Exhaust

In addition to condensation from the air conditioning system, it’s also possible to get natural condensation in the exhaust. This usually happens when it’s cold out, and you first start your car after it has sat for a while. So if you notice some water sputtering out of your tailpipe on a chilly morning, there probably isn’t anything to worry about.

There are some situations where water in your exhaust is cause for alarm. For instance, a blown head gasket can result in coolant dumping into the combustion chambers and burning along with the air/fuel mixture. The result can be an extraordinary amount of water in the exhaust, or massive plumes of white mist.

If you suspect that your engine might be burning coolant, you should keep an eye on the coolant level. In the absence of an external leak, the coolant level should remain constant. So if you find that you have to add coolant regularly, there’s a chance that you’re dealing with a head gasket leak.

Reasons For Water Dripping Out From The Exhaust

If you notice that water is dripping from the car through the exhaust system, then it can be as a result of the following issues;

Engine Combustion And Water Condensation

As combustion takes place in your vehicle’s engine whenever the vehicle starts, a mixture of water and carbon dioxide is formed. When the engine cools down completely and exhausts gases exit the combustion chamber, condensation of water and carbon dioxide can be noticed much more, and in a moment like this, you notice water dripping from your car through the exhaust pipe. This is completely normal and you don’t have to take your car to a professional.

Catalytic Converter By-Product

Catalytic converter plays a major role in reducing the pollutants that go into the environment. It transforms the by-products of vehicles into substances that do not harm the environment. It converts the toxic waste products of the vehicle into non-harmful components as in water or gas form.

Water dripping out from exhaust is an example of a catalytic converter working at its best. This is not something that you should be worried about.

Condensation From Heat

If your car is in a colder climate, it will need to warm up before it can work properly. This causes excess heat to be built up in your car and is later expelled through the tailpipe.

That heat will produce condensation in your exhaust system, so you will see water droplets coming out of your tailpipe. This has the potential to be dangerous, but all you need to do is let the engine run for a few minutes before you start driving.

Smoke And Water Emissions

If you notice smoke and water coming out of your tailpipe, this could be a big warning sign that your pistons are not working properly. If the situation is a more serious one, you might also notice a burning smell or a sweet smell.

This is very serious and you should get your vehicle checked out by a mechanic as soon as possible to keep your car safe and sound on the road.

A/C Leaks

It is possible that what appears to be a leak is not a leak at all. The air conditioning evaporator is located under the dashboard of the car, either in the middle or on the passenger side. Moisture typically condensates on the outside of the evaporator whenever the air conditioner is in use.

If the drain tube comes loose or is blocked by debris, this condensation will drip on the inside of the vehicle floor causing a wet floor.

This is a simple problem to repair, requiring only the cleaning out and reattachment of the drain hose. To clean any debris out of the hose, run a piece of weed eater line through it.

Another cause of leaking inside the vehicle, besides water, is coolant from the car’s engine. The air conditioning evaporator is part of the vehicle’s heater. The conditioning evaporator looks like a small car radiator.

This uses engine coolant to bring heat from the engine into the vehicle. Just as a radiator can have a hole in it, this coil can as well. It will cause coolant, which is sweet-smelling and slightly sticky to come into the vehicle, under the dashboard.

Repairing a heating core requires removing it from the vehicle and replacing it. Depending on the design of the vehicle, it may be necessary to remove the dashboard or part of the dashboard to access the heater core. This is a time-consuming and expensive repair and should be performed by your local service repair professional.

Common Causes Of Car A/C Leaks

The following are some factors that can lead to water dripping from your car through the AC compressor;

Clogged Evaporator Drain

Condensation and excess water leave your car through an evaporator drain. This is good. The water should flow out of your car through the evaporator drain. Sometimes, though, this drain can get blocked by dirt or debris.

Like water in a clogged sink, the condensation from your A/C can back up. Once the evaporator core overflows, the moisture will make its way to the A/C vents, eventually turning into those annoying puddles of water you keep finding in your cabin.

It’s crucial to unclog the drain as soon as possible. If excess water remains in the evaporator core too long, it can damage electronic A/C components like the resistor, which controls fan speed, or the blower motor, which powers the entire system. But your average grocery store drain cleaner can’t fix a clogged car A/C. So please don’t try it.

Faulty Seals

If plastic or rubber seals in your A/C system fail, water can seep out of the system and into your vehicle cabin. If this is the case, you’ll probably notice the water pooling up under the passenger side floor mats.

Leaking Evaporator Core

An evaporator core looks similar to a radiator almost like a big grate. Leaves or other organic material can reach the evaporator through the air intake vents. As this material breaks down, it becomes corrosive and can cause your evaporator core to rust, allowing water to leak.

If you notice a musty smell coming from the vents when you initially blast the A/C, you’re probably getting a whiff of those rotting leaves in your evaporator core. If this is the problem, the evaporator will need replacing.

What To Do Once You’ve Found The Leak Of Water Dripping From Car

There’s not much point in drying out the car until you identify and stop or at least lessen the leak. Once you do though, you need to dry out the inside of the car thoroughly because a damp car will go moldy very quickly.

Even if it looks clean, there could be mold in the carpet or doors, and you could drive a car that smells like a compost pile.

So once you’ve found and fixed the leak if it’s wet and you can remove it, remove it. The seats, carpets, and door panels are easy to remove and put in the sun to dry. Mop up as much liquid as you can with something very absorbent, like kitchen paper towels.

When you’ve got it as dry as you can, either use a plug-in dehumidifier or a plastic tub full of desiccants left in the car with all the windows closed for 24 hours. Some people also swear by leaving a tray of cat litter in the car too.

It may take time to dry the car completely, so whenever you drive the car have the heater on and windows opened slightly to aid ventilation.

Is It Safe To Drive When Water Is Dripping From Your Car?

Whether it’s safe to drive after you notice water dripping from your car depends on where the water is coming from. So if you don’t have time to check the source of the water, or verify that it is water, then playing it safe and using other means of transportation may be a good idea. This is especially true if you’re about to head out on a long trip that could leave you stranded in the middle of nowhere.

If you can verify that water is dripping from your car, and it’s coming from somewhere near the back of the engine compartment, then it’s probably safe to drive. Since this type of “leak” is almost certainly just air conditioning condensation, there’s usually nothing at all to worry about.

Water from the exhaust is a simple case since it rarely shows a problem. So if there is water dripping from your tailpipe, your best bet is to check the coolant level once the engine has cooled down and decide at that point. If the coolant isn’t low, you’re probably fine, while low coolant may or may not show a problem.

Conclusion – Water Dripping From Car

Troubleshooting water leaks in a vehicle can be challenging, as the entry point for the water may not be where the water is appearing on the inside of the vehicle. It may be necessary to remove interior trim panels to gain access to the vehicle’s body and see where the leak is originating from.

The more information one has about when the car is leaking and under what conditions it is leaking, the easier it is to determine exactly what is causing the leak.

You may also like

Leave a Comment