How to tell if there is water in your car’s fuel tank

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One thing that could cause problems for your car is if water gets into the fuel tank. There are several ways through which this could happen. This messes with the compression and combustion of fuel, and might lead to engine failure. Here are ways that water could enter your petrol tank:

  • The chances of water entering the gas tank increases if the tank has a bad top fuel pump.
  • Condensation of atmospheric moisture leads to accumulation of water vapor into the petrol tank.
  • If groundwater seeps into the storage tank at the filling station, you could pump in water along with petrol when filling up your tank.
  • A poorly sealed cap on the tank can let in water from rain or regular car washing into the tank.Fuel tank


  • Hydrolock: A hydrolocked engine has water inside the combustion chamber, which prevents combustion and compression. The engine will be unable to start if this happens.
  • Engine stalls: The engine may start and maintain itself for a while. However, combustion might be weaker than normal and this may lead to stalling.
  • The engine will not start: The engine may turn over while the ignition is engaged, but there won’t be a proper operation due to a lack of proper amount of fuel.
  • Poor fuel economy: The water will reduce engine power, yet the engine wil burn the same amount of fuel. This results in burning fuel for reduced mileage.
  • The tank begins to rust: This is due to the fact that water is heavier than petrol, and therefore it settles to the bottom of the tank.
  • The watered-down fuel in a car makes it sputter and lose power.
  • Water in the petrol tank leads to bio-degradation of fuel.


  • The best way to remove water from the tank is to remove the entire contaminated fuel in the tank. Then replace it with a high quality, non-ethanol blend petrol. Fuels containing ethanol have a short shelf life, and absorb excess water within a few weeks.
  • You could fill the tank with high levels of octane petrol, then quickly exhaust the petrol tank. This will leave the tank dry and exhaust all the moisture.
  • There are products that contain special fuel additives and methanol, which help to remove water in the tank. However, this will not work if there is more water in the fuel tank than fuel.
  • Consult a mechanic.

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