How to tell if you have water in your fuel

Written by jenna marie
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How to tell if you have water in your fuel
It's not uncommon for water to mix in a boat's fuel tank. (Big Boat, Little Boat image by Aubrey Thompson from

Generally a result of condensation, bad gas or a mean prank, water in the fuel mix can negatively impact the performance of your car or boat. Learn the signs that your car or boat gives off when there is water mixed in with the fuel so you can take it to the mechanic to fix the problem.

Skill level:
Moderately Easy

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Things you need

  • Fuel test kit (optional)

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  1. 1

    Watch for a sluggish response in your car or boat. When there's too much water in the gas, the vehicle won't respond to a small tap on the accelerator, according to experts. Instead, the car or boat will accelerate slowly and may even sputter a few times before catching. This occurs because the engine isn't designed to burn water the same as fuel.

  2. 2

    Check for evidence of rust in the fuel system, especially around the fuel pump. The fuel pump brings gasoline to the engine in just the right amounts. When too much water enters the fuel system, the internal parts can be exposed to rust. The fuel pump in a car or boat can fail if there is too much dirt or rust in the tank, according to

  3. 3

    Monitor the gas gauge carefully to make sure it truly represents the amount of gas in the tank. If there is water mixed in with fuel, the vehicle's gas gauge will read higher than it really is. Because the gauge can't tell the difference between water and fuel, it will indicate how much liquid is in the gas tank, according to This false reading can cause a driver to run out of fuel even though the gas gauge indicates the tank is not empty.

  4. 4

    Use a commercial test kit to determine if water is present in the fuel. Simple kits are available that test for a number of things in fuel, such as excess ethanol and water. The test kits include a bottle, rubber cap and a solution that identifies any water.

Tips and warnings

  • You can purchase products that pour into the gas tank and evaporate any water mixed in with the fuel. This is the least expensive way to remedy the problem.

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