Have you ever been parked for a while and realized that there was water coming out of your exhaust pipe? While Washington is a pretty rainy state, water coming from the exhaust can be alarming for obvious reasons. The good news is that in most situations it’s normal and even expected to see water coming from your tailpipe, especially here in Tacoma, where we have a colder climate ¾ of the year. 

Still, it’s good to understand the reasons why this happens. It’s also good to be aware of when it isn’t normal so that you know when to bring your car in. 

Normal Causes of Water Coming out of Your Exhaust


Water coming out of your exhaust right when you start the vehicle may be a little concerning. However, it turns out this ‘issue’ isn’t actually an issue (in most cases). 

While it’s untrue to say that weather causes water to come out of your exhaust pipe, it is true that colder weather can make this normal product of combustion that much more noticeable. When you start up your engine, the gears, pulleys, and other components within begin to move and turn. This creates heat.

When this heat meets water vapor in cold air, the result is  water coming from your exhaust. 


water coming out of your exhaust

One of the top reasons that water is coming out of your exhaust pipe is condensation. 

In simplest terms, combusting fuel in the engine is what makes your car go vroom. The result of this combustion is a combination of  CO2 and water. When this combination of gasses exits the combustion change in the form of exhaust, they can coat the inside of the tailpipe. Once the car has had time to cool, this condensation drips down, forming the small puddles of water you see.  

Catalytic Converter

Water coming out of your exhaust can also be a sign that your catalytic converter is doing its job. Catalytic converters are basically the sanitation system for your car’s emissions. Before catalytic converters became standardized for vehicles, the toxic carbon gas that is the byproduct of engine combustion was released directly back into the air. The job of the catalytic converter is to reduce the particle size of the particles and clean up emission before they are released back into the atmosphere. 

A result of a properly functioning catalytic converter is water vapor. This, of course, becomes the water you see in your driveway or on the garage floor. 

water coming out of your exhaust

When to Worry

Like we said at the beginning of this blog, water coming out of your exhaust pipe is normal, usually. There are some circumstances that definitely warrant a trip to your local auto shop. 

If the water coming from your exhaust is coupled with smoke (not vapor) and a burning smell in the cabin, you may have an issue with your pistons or piston rings. 

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If you are concerned about an issue with your vehicle with water coming out of your exhaust, please bring it into Courtesy Auto and Tire of Tacoma. We’ll help diagnose the problem and get you back on the road in no time.