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Why is Water Leaking from My Car? 

If you’ve noticed a puddle of fluid under your vehicle, it can immediately make you anxious and doubt your car’s reliability. Sometimes it’s a minor issue while other times it could be a sign of major problems. And in other cases, it’s harmless and completely normal, which is the case with water leaking from your car.

A water leak outside your car is usually not something to be concerned about, but other fluids can be clear or look like water too. The key is to first identify the fluid correctly, then determine if there’s a problem that needs to be addressed.

What does it mean when you see a puddle of fluid under your car? 

The fluids your car uses as lubricants are all intended to be contained. Engine oil and transmission fluid along with other driveline fluids, power steering fluid, brake fluid, and engine coolant are all supposed to stay within their respective systems. The only exception is fuel, but that shouldn’t ever leak – it’s consumed by the engine instead.  

Water, on the other hand, is almost always a byproduct of some other system that’s working like it should. For example, the air conditioning system condenses water vapor out of the air in your car’s cabin to make it feel cooler, and the water droplets run out of the HVAC housing through a drain and exit by the firewall. Or, the combustion process creates fumes in the exhaust that are converted to water vapor by the catalytic converter, and the water drains from small holes in the muffler or tailpipe.   

If you see a puddle underneath your car, the first step is to identify the fluid and determine if it’s normal or needs to be addressed.  

How to identify the fluid leaking from your car 

So you’ve said, “My car is leaking water from the bottom.” There can be several different types of fluid that leak under your car, and identifying the fluid is the jumping-off point for getting it resolved. Here’s how to determine what the fluid is. 

  • Water. If the puddle under your car is water, it will be clear and colorless as you expect water to be. There might be a slightly oily residue shimmering on the top which is just a trace amount it collected as it ran down or picked up from the ground. When you touch it and rub it between your fingers, it will feel like water, not viscous like oil. And when it dries, you don’t see where it was previously. 
  • Engine oil. On the ground, engine oil looks dark brown or blackish. It might smell slightly burnt as well. When you rub it between your fingers, it feels slick and doesn’t go away without wiping it. If it sits for awhile, it soaks into the surface and leaves a dark stain. 
  • Transmission fluid. If the fluid has a reddish appearance and carries a pungent odor, it’s probably transmission fluid. Like engine oil, it has a viscous feel between your fingers and looks almost the same when it absorbs into the ground. 
  • Brake fluid. A puddle of brake fluid can look like either engine oil or water on the ground. You’ll be able to tell the difference if you touch it since it feels more like oil than water. If it’s wiped up promptly, brake fluid seldom stains concrete. 
  • Power steering fluid. It shares properties with transmission fluid, and some systems use ATF for their power steering systems.  
  • Engine coolant/antifreeze. This fluid is often tinged green, yellow, or orange, although other colors are possible. It feels like water when rubbed between your fingers, but it has a noticeably sweet smell to it. The exception is if the coolant has been drained and filled with only water – which isn’t a good idea at all – but it is possible. 

How to correct the issue 

Since we’re concerned about identifying a car leaking water, let’s focus on those potential issues.  

First, determine if the water is from your car. Is it possible you parked over someone else’s leak? If it’s in a parking lot or another shared location, it might not be your concern to deal with at all. If it’s an assigned spot or your personal driveway or garage, that’s a different matter. 

Then, identify the system above the leak.  

  • Is it near the firewall? It could be the AC is normally discharging water from the drain tube. There’s nothing to be concerned about. In hot and humid or rainy weather, more water vapor is condensed and drained, so there’s typically higher volumes dripping at those times.  
  • Is it under the muffler or tailpipe? Water vapor is formed as the catalytic converter superheats harmful chemicals in the exhaust. Small drain holes in the exhaust system allow water to drain out at low points, preventing rust from collecting and corroding it from the inside out. 
  • Is it under the engine or radiator? Check that the coolant is strong enough and properly mixed.  

Also, keep in mind that drivers in cold weather can get icy or snowy buildup in unexpected places. When it begins to melt, it can make it look like you have a leak, but that’s not the case. If that’s a possibility, park in a heated garage for a day to let your car melt out, then check it again. 

If your car is leaking anything but water, get the parts you need to fix it at AutoZone. Get Trustworthy Advice from our associates and find all the parts, tools, and equipment to get your car back in shape quickly. If the job is too big for you, seek out one of our Preferred Shops to help you do the job.

FAQ/People Also Ask 

Why is there water dripping from under my car?  

In almost all cases, a water leak under your car is normal. It can be from the AC drain or from condensation in the exhaust that’s dripping out. 

Is it normal for a lot of water to leak from car? 

It can be a surprising amount of water that drips from your car’s AC drain tube. The higher the humidity and the colder your AC is set for, the more water you’ll see. 

Why is my car leaking water but not overheating? 

Overheating can be attributed in some situations to a coolant leak, but that’s seldom just plain water.  

Should I be worried about water under my car?  

It’s always a good idea to find the source of a leak. However, if it’s water, it’s almost always a normal byproduct. 

Is it water or coolant leaking? 

If there’s no odor or color, it’s likely water. If there’s a sweet smell or the fluid is yellow, green, or another bright color, it’s probably coolant. 

Can I drive with a coolant leak?  

It’s never a good idea to drive with a coolant leak. It can cause serious, expensive issues if your engine overheats. 

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