Car Diagnostic

Symptoms Of Water In The Gas Tank And What To Do?

Mike Cross
Updated Feb 22, 2022

Having water in your gas can bring with it a host of problems, no matter how little the amount is. The fuel systems on cars are made to be sealed from outside moisture, dust, or debris. And by introducing a foreign matter into it you could run the possibility of serious mechanical complications.

Since all fuel is oil-based, the two simply can’t mix. Besides, if engineers could make vehicles run on water, they would have done it already.

This article is intended on helping you get as much information as possible when you think you have water in your gas tank. Knowing what to do in this situation can help reduce the chance of needing serious repairs to your car.

How does water get in gas tank?

If you've determined that you have water in your gas tank; besides getting it out as soon as possible, realizing how it got in is the most important thing. There are three main ways done water can enter your fuel. Keep in mind that these are just the three most common ways, but there are other methods of water entering your fuel system.

Through the gas cap

No matter how hard you try, sometimes you blatantly forget to put your gas cap back on after fueling up. We've all seen those people that drive away with their gas tank door wide open and the cap off. It also triggers the check engine light on.

Luckily, most times people will catch onto it and promptly put the gas cap on. but in unfortunate cases, it can be hours or even days until they have realized the cap was off. If it was raining during that time, conditions become ideal for getting water in your gas tank.

Poor quality fuel

Ever wonder why one gas station has a cheaper price on fuel versus another? It may come as a surprise to some, but not all fuel is made the same. On top of that, some gas stations do not change their water, fuel separator filter on time, which only ends up causing more problems for their customers.


Condensation is all around us and there isn't much we can do about it. In fact, without condensation, we wouldn't be able to breathe at all since we need water to live. it is a necessary evil that mankind has learned to deal with when building cars.

Unfortunately, in high humidity situations, condensation poses a higher risk of contaminating the fuel system on a car. The best thing we can do, especially when humidity levels are greater than normal, is to keep our fuel tanks topped up. Having a full tank of gas leaves no room for condensation to build up.

Symptoms of Water In The Gas Tank

Recognizing the symptoms of water in the gas tank is crucial. By knowing if moisture has somehow made its way into your fuel system, you can help resolve the issue faster and with less money.

So, what are the symptoms of having water in your gas tank?

Loss of power

If water enters the fueling system of your car, one of the first things people notice is loss of power. If there is no fuel, there is no spark. No spark means no power. You get the idea.

Although a loss of power can be one of the main symptoms of most car troubles, combining it with one or more of the indicators listed here can help give you a better idea of what is going on.


You put your foot down, and you get nothing but a whole lot of hesitation. You are thinking to yourself: “I can’t be out of gas, I just filled up!”.

Chances are that if you just filled up, and as you are pulling out of the gas station the car starts to act funny, there could be moisture or water in the fuel you just put in. This scenario is not likely, however, it’s not impossible.

Bad Fuel Mileage

Having water in your gas tank can lead to a drop in fuel economy. No matter how big or small your engine is, getting the most out of this is crucial.

Not delivering the right amount of fuel when the car’s ECU calls for it will result in incomplete combustion. Any change in gas mileage should be noted and looked into as it may be a good indicator that something is wrong.

What to do if you have Water In Your Gas Tank

If you notice any of the above symptoms and you think you think there is water present in the fuel system, here is what you should do.

Replace the old gas

Even if you've just filled your car up with gas you must drain all of the gas from the car to get any remaining moisture out. This may sound expensive now, but in the long run, it could help save you from replacing fuel injectors, fuel filters and other expensive parts in the future.

This process is best left up to a professional as the fuel lines leading up to the engine may have to be flushed out as well. Simply draining the fuel tank in this situation won't solve the issue.

Let The Fuel Tank Dry

Once all the fluid has been taken out the system should be left to dry for anywhere from a few hours to a few days just to make sure any remaining moisture will be evaporated.

Not taking your time on this step could actually worsen the situation. A few extra hours now would mean a lesser chance of problems further down the road

Fill Up With High-Quality Fuel

Once you are confident all of the moisture is out of the fuel tank, we recommend filling up your gas tank to the very top. This way, moisture will not be able to form inside the tank.

On top of that, add some fuel additive. There are special formulations specifically made to draw moisture out of fuel.

While gasoline-powered vehicles don't run the chance of catastrophic engine failure as often if there is water present in the fuel.

 Diesel-powered engines, on the other hand, may be at greater risk of having their engine seize up if water has made its way in the fuel. Most big rigs and heavy-duty trucks have a fuel/water separator for this reason alone.

Final Words

So there you have it, everything you need to know about having water in your fuel tank, The more you know about this issue, the more likely you are to catch it in time, preventing any significant harm on your engine.

There are a series of preventative steps you can take to make sure no serious or permanent damage is caused to your pride and joy.

Don't forget to leave a like and comment so that we can get you more information like this. Do you have any questions or concerns? Don't hesitate to reach out please don't hesitate to reach out to us.  We're here to help.

Mike Cross
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