How do I get water out of my car or truck's fuel tank?
This may depend on how much water is actually in your fuel tank. Very small amounts could probably be managed with "fuel-dryer" additives, which combine with the water in your fuel and simply run it through the engine. If the water problem is serious, you should have a competent mechanic resolve the problem. This may include removal of the fuel, fuel storage tank from the vehicle, cleaning it, replacing the fuel filters, re-installing the tank, and filling with fresh, clean fuel.