What Are the Treatments for Water in a Car's Fuel Line?

by Ronnie Daniels
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Gasoline can become contaminated with water because of condensation in fuel storage tanks and in your gas tank. Water is denser than gasoline and will sit on the bottom of the fuel tank until the level of fuel gets low; then the water can be sucked into the auto fuel lines and damage your engine. There are several ways to prevent water from getting into your fuel line. Mechanical devices separate the water from the gas, and chemical fuel additives can remove water as well.

Fuel Additives

Fuel additives to remove water from your gas tank and fuel lines are different types and concentrations of alcohol. Isopropyl alcohol, ethanol and methanol are all used to remove water from fuel. For best results, add the fuel additive before filling the gas tank with fuel. That way the alcohol will start to absorb the water in the tank right away. Alcohol can absorb water and hold it in suspension. The fuel additives available for automotive use will hold up to 50 percent water in solution before separating back out from the excess water. The alcohol removes the water by passing the suspended water molecules through your engine and out the exhaust.


In tropical climates many automobiles are fitted with filters to trap the water before it can get into the engine fuel line. Some of these are similar to the fuel filters found on your car now and need replacing at regular intervals. Diesel-powered vehicles also are equipped with water-trapping filters. Other filters have a bleeder valve on the bottom to drain out accumulated water and other contaminants. Opening the valve and allowing it to drain until only fuel comes out will remove the water contaminant. These filters are important in areas with constant high humidity because condensation in the fuel storage tanks and in auto fuel tanks occurs more frequently.


It may sound a little unorthodox, but WD-40 will remove water from your gas tank. Put one ounce of WD-40 per gallon of gas into the tank before filling it. The name WD-40 means water displacement fortieth attempt. Norm Larsen invented the product in 1953 to prevent corrosion by removing the standing water that causes it. His fortieth attempt was successful, and so the product is called WD-40.

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