What are Common Causes of Water Leaking from under a Car? (2024)

FAQs

What are Common Causes of Water Leaking from under a Car? ›

There are some very common causes for that water under your car, including: air conditioning, exhaust, and the windshield washer fluid reservoir. If the puddle under your vehicle is colorless and odorless, there is a good possibility it is just water dripping from your vehicle's air conditioning system.

Your car leaking water, especially near the back of the vehicle, is normally caused by air conditioning condensation or exhaust condensation. Both of these kinds of leaks are normal. Your biggest concern should be if the liquid isn't water, but there are easy ways to test that in your Arlington home.

If it's clear or light-colored, it's probably just water from your car's air conditioning system or exhaust system. No need to worry about that! However, if the fluid is dark-colored or oily, it could be anything from engine oil to transmission fluid.

There are a few conditions that can explain why your vehicle has water on the floor, ranging from worn-out seals to clogged drains to broken-down heating and cooling components.

Replacing the water pump and gasket should be in the plans. For minor leaks, you'll notice a white trail of residue where it drips down the front of the engine, tinged with the color of your coolant. The leak may never reach the ground because the heat from the engine dries the coolant on the metal surfaces.

Causes of Water Leaks Under a Vehicle

If the puddle under your vehicle is colorless and odorless, there is a good possibility it is just water dripping from your vehicle's air conditioning system. This is actually the most common culprit.

Pour some water pour all around the trunk lid, then open the trunk again. If there's any moisture around the taillights, that might be your leak. You can then replace the seals around the taillights to stop the leak. If your car is a bit older and still has a radio antenna, check that seal as well.

Engine oil is the most common type of fluid leak. If the puddle of liquid is towards the front of your vehicle, its source is probable the engine. Dip your finger or a piece of paper towel into the liquid. If it is engine oil, the fluid will be brown or black, slick to the touch, and have a slightly burnt odor.

What is the most common leak in a car? ›

Light Brown to Black: Engine Oil

Let's start with one of the most common leaks you're likely to see in your driveway or parking spot. An amber-to-brown/blackish colour spot is a telltale sign of motor oil. The good news is that a little drip is relatively standard and isn't likely cause for concern.

Over time, those rubber seals can start to dry up, become brittle and damaged and could even begin to leak. When it rains, that water might find its way into your car through bad weatherstripping. If you park outside, making sure your car's weatherstripping is in good shape is even more important.

Car leaking water – what to do

Usually, leaking water is simply condensation from the aircon unit – surprisingly common during summer – or the exhaust, which is more common in winter. Another typical cause is your windscreen washers, but again this is unlikely to be a major issue and you can probably just ignore it.

Some under-car puddles are more worrisome than others.

Engine oil leak. Brake fluid seepage. Transmission fluid leakage. Power-steering fluid dripping.

If you notice a clear and odorless fluid underneath your car, then it's probably from your car's air conditioning system. The air conditioning system of your car is the most common source of a water leak; thankfully, it is usually not serious.

Usually, leaking water is simply condensation from the aircon unit – surprisingly common during summer – or the exhaust, which is more common in winter. Another typical cause is your windscreen washers, but again this is unlikely to be a major issue and you can probably just ignore it.

The most important thing you can do in this situation is to stay calm. As soon as you hit the water, open your window. This is your best chance of escape. Usually a car will float for a brief amount of time, which should give you time to get your seatbelt off and then open a window.

There is a membrane behind the door card – usually a sheet of either polythene or thin foam. Water can enter the body of the door when it rains, and generally drains out of holes in the bottom of the door. But if the membrane gets ruptured or torn, water can run down the membrane and soak into the door card.

Rainwater can get into a vehicle by seeping past weatherstripping on windows and windshields -- the black rubber seals that border your vehicle's glass surfaces. Over time, those rubber seals can start to dry up, become brittle and damaged and could even begin to leak.