By no fault of yours water can get into your fuel tank through adulterated fuel or by getting in through a badly sealed cap on the tank, or by natural condensation on the inside of the fuel tank. When this happens, you must first of all know that fuel and water don’t mix. As long as your car is pumping fuel and not water, it will be reasonably OK. The problem is that water is more dense than petrol and the fuel will float on top of the water, this means that the fuel pump, which is fed from the bottom of the fuel tank will be trying to pump water. If the car runs at all, that means that there is very little water in the tank. In that case there is no cause for concern. The moisture will get burnt with the fuel. If on the other hand, there is a layer of water in the tank, that will be pumped into the cylinders. The car is unable to run on water and water is effectively incompressible.
A good way of knowing there’s water in your fuel tank is a sudden change in the performance of your vehicle. You try to accelerate and the car hesitates or sputters consistently. You try to get up to highway speeds and the car just doesn’t want to cooperate. Or maybe the vehicle sputters and then revs and jolts to higher speeds when it shouldn’t. Then you have a water contaminated fuel.
The best way to remove all water from the fuel tank is to simply replace the entire volume of fuel that is being used. This may seem like an expensive alternative to some drivers; however, the damage that you will be avoiding to your car is more than worth it. Depending on the amount of water in the tank, you may want to leave it empty for a while so that it can dry out. A mechanical professional should be able to do this for you.