How To Know If There Is Water In The Gas Tank?

Did you accidentally leave the cap of your gas tank off and now it has started raining outside? Or the gas station which you filled up recently has a damaged water filter and has let a water slug enter the tank along with fuel.

It is not condensation as most of the vehicle fuel tanks are sealed systems which are not safe from condensation the way big fuel storage tanks can be. From wherever it came, water in the gas tank is a serious issue that needs to be checked immediately.


Here, I have provided everything you need to know about water in the gas tank, from how to find out if your gas tank is filled with water in order to resolve the issue. You will find the steps easy to understand.

water in gas tank

What Are Symptoms Of Water In The Gas Tank?

If the water is mixed with fuel in the gas tank, then it may lead to various problems.

Water can get into the gas tank of the vehicle in a lot of ways, here are some of the ways to check if water has entered the gas tank of your vehicle. Here are some of them:

Car Gas Tank

1. Acceleration problems

Another option is to drive the car and give an attention after pressing the accelerator. Sputtering, loss of power or coughing are symptoms that your vehicle may be having a bad fuel.

Your vehicle may hesitate or jerk when you press the pedal of the gas. You will find that it will not accelerate properly or its speed will decrease suddenly when you drive.

2. Fuel Issues

Water dilutes the gas, and if water is present in your gas tank, then you should fill up the water tank more often than required.

car repair

3. No Power

No matter how hard you are trying, your car may not start at all. It may seem that your gas has finished. Your vehicle will be idle and then immediately shut down.

4. Damaged fuel system

Water has more weight than gasoline. Therefore, it will be at the bottom of the gas tank. Most of the vehicles are not able to pump gas from the bottom of the tank inside the fuel system, and if the tank is empty, the vehicle may pull the water inside.

The water on the tank bottom can be transferred with the hoses and pipes leading to damage and rust with time.

Red fast sports car in spotlight, black background. Shiny, new, luxurious. 3D rendering

5. Gas gauge condition

If the fuel quantity is low and you think that its quality is not good. Fill up the tank with fuel having a high percentage of high octane and add a good quality fuel treatment to it to resolve the issue.

If the fuel tank of your vehicle is full, then you should contact a mechanic & get advice from him to manage the situation. The watered gas needs to be changed with the premium gas.

6. Car engine condition

Pay attention to it when it is idle if it surges, sputters or stalls out consistently. These are all signs of bad gas.

car under the sun

7. Start your car and pay attention to whether it starts properly or not.

Start your car and pay attention to whether it starts properly or not. If it gets difficult to start or it stops again and again, even when it gets started. And the only recent change you have made to the vehicle is put gasoline in it; you might have water-filled fuel.

8. Fuel is older than a month

Usually, the gas which has ethanol in high concentrations do not have a long shelf life and leads to “phase separation” in less than 30 days. Phase separation happens when water and ethanol are bonded together and are separated from gasoline.

If it's been a month since you filled your gas tank, then you need to understand that it is no longer good and needs to be drained out of your vehicle tank with the help of a mechanic.

How To Take Away The Water Out Of The Gas Tank?

Water in the vehicle tank will lead to various major issues for the car. Water makes the fuel dirty and saves it from getting burnt in a similar way as nicely as gasoline that will cause the engine of the vehicle to use up more fuel.

Water will also lead to the corrosion of the parts of the engine of the car especially the combustion chamber and piston. As a result of which, it is important to remove the mixed gas from the tank of the car as early as possible.

Refill and filling Oil Gas Fuel at station flare light,energy

​List of things that you will require

  • Fresh gas( 3 gallons)

Steps you need to follow

1. Attach the copper tube to the with rubber tube

Put any one of the ends of the copper tube inside one end of the rubber tube having a length of 8-inch. Seal the areas of attachment with the help of electrical tape.

rubber tube of length 8” and 3/8” diameter


Copper tube having 4” length and 3/8” diameter


2. Attach the primer ball to the with rubber tube

Take the other side of rubber tube and attach it to any of the ends of primer ball by placing rubber tube end inside the ball valve.

Place any one end of other rubber tube piece inside the other valve present on the primer ball’s other side. Seal the attachment areas using an electrical tape. The apparatus can be used as a fuel emptying device.

3. Put the copper tube inside the gas tank

Place one of the ends of copper tube inside gas tank. Keep the tube inside the fuel line till you feel and touch the gas tank’s bottom.

Copper tube having 4” length and 3/8” diameter

Source: ​

4. Empty the gas tank with a primer ball

Place one end of the rubber tube inside the empty gas tank and press the primer ball. This will take the water out of the tank inside the can. Continue the process till the gas tank is emptied.

5. Purify the watered gas

Mix a dry gas bottle of 8 oz. and 3 gallons fresh gas with watered gas in the gas can. Shake the can gently to make sure that the fuel is mixed properly. Pour the fuel from the gas into the gas tank of the vehicle.

Gas nozzle dumping gas in a glass


Recently, many cases have been occurring where Ethanol gas has become a leading cause of damage to fuel systems and engines. Ethanol enhanced fuel has led to serious damages in small to large engines.

The most critical problems are water fouling and fuel separation. I used to struggle with this issue after every two or three months. Therefore, I prepared the easy to follow guidelines to remove water from the tank.

The article is written to tell you everything you need to know about water in the gas tanks. Hopefully, the article has answered all your queries regarding water in the gas tanks. Do let me know if you found the article informative.


Hi there! I’m Jordan, chief editor of Crush the Road and I’m a self-confessed automative fanatic. Cars or vehicles has always been a passion of mine and will always be my favorite pastime. Now that I am married and has one adorable son, I have the time to write and share my personal experiences with other automative enthusiasts like me. Welcome to my fantastic blog!

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