4 Causes of Water Coming Out of the Exhaust

In the normal course of events, you won’t see water coming from the exhaust system of the vehicle. But if you notice that your tailpipe is leaking or dripping water out from it, then it means your exhaust system must have water inside it. This is no reason to be alarmed because the cause is usually no big deal.

However, it would be a good idea to get this situation investigated and diagnosed by a professional mechanic if you’re not confident in your abilities. Otherwise, it could create a worse outcome that will cost you hundreds or even thousands of dollars.

In most of these situations, it will be no big deal. The worst case would normally be that you would have to replace a small component or two which will cost you a few hundred dollars. Below are some common causes of water coming from the exhaust in normal and abnormal conditions.

Reasons Why Water is Coming Out of Your Tailpipe

1) Condensation (Normal Cause)

condensation from exhaust

After your engine has just performed the internal combustion process, there is a carbon dioxide and water mixture that forms as a result. Once your engine has been given some time to cool down, there are remaining exhaust gasses which leave the chamber and come out of the tailpipe.

The condensation of these gases is more apparent which means that you will be able to see the water dripping from the tailpipe.

2) Catalytic Converter (Normal Cause)

symptoms of a bad catalytic converter

When the exhaust system emits toxic carbon gases, the catalytic converter is responsible for reducing the size of these gases before they come out from the tailpipe.

This allows the vehicle to be more environmentally friendly while reducing the risk of harming other people in the process.

However, as the catalytic converter works to reduce these toxic emissions, there is a small amount of water vapor that forms as a result. This water vapor will form little droplets that will come out from the tailpipe.

3) Engine Heat (Normal Cause)

water from tailpipe

If you live in an environment with cold temperatures, you can expect to see water coming from your exhaust. The components of an engine normally need a little bit of time to let the oil circulate through them in order to cool them down.

In the meantime, the moving components of the engine are going to generate a lot of heat within the first couple of minutes after start up. The exhaust system is also going to be unusually hot too.

Because of this, water vapor is produced as the heat merges with the cold air. Then you’ll see small water droplets falling from the tailpipe along with a bit of what appears to be white smoke. Just wait a few minutes with the engine running and they should all clear up.

4) Faulty Piston (Abnormal Cause)

bad piston

It can be serious when a bad piston is causing water to come from your tailpipe. You’ll know if the pistons or its rings are the cause because you will also see smoke come out of the tailpipe in addition to the water.

If it is really bad, then a burning smell will fill the interior of the cabin. Either that or it might be a sweet aroma that would indicate an even bigger problem.

So, if you experience any strange smells along with smoke and water coming from your tailpipe, then don’t drive your vehicle. Have it towed to an auto repair shop and have them confirm it’s your pistons and/or piston rings and replace if necessary.

12 thoughts on “4 Causes of Water Coming Out of the Exhaust”

  1. I have my mechanic replace my cylinder head. But I still notice abnormal quantities of water coming out of my car’s muffler. May I know the possible causes?

    • Water out the tailpipe from a blown head gasket will appear as white smoke, and is pretty hard to miss if the leak is bad. If it’s just water droplets, this could be normal condensation. It’s possible you’ve always had this level of moisture coming out, but it is more noticeable after the repair because you’ve been paying more attention to the car. I know I tend to do this after I notice a problem.

  2. What if the vehicle runs 24-7 for weeks at a time? The vehicle is used for security purposes.What would the cause of water coming out of the exaust?

    • If the vehicle is used for security purposes you should really consult your own mechanic over an internet resource. It’s hard to know for sure without seeing it in person, but my gut tells me it’s probably fine if it’s just a few drops of water here and there.

  3. Car idles fine however when reviving to 2.5k rpm and releasing throttle. The car throw out quite a bit of water out of the exhaust as if its filling up then blowing it out. Also slightly smokey (white), is this the head gasket blown?

  4. My car is running really rough and is sluggish and has quite a bit of water coming out of the tail pipe but no smoke. Any idea what would cause this??


Leave a Comment