You have two choices. You can do the right thing, or you can do the wrong thing. If you know you have water in the tank, drain it. This would be easier if you take a moment and convert to an electric fuel pump as most of us have. You can just disconnect the feed to the filter head, and pump the tank out with your new electric lift pump. That's easier than pulling the tank and pickups and draining it. If you let the truck sit still on flat and level ground, the water is going to come out first anyway, so you may not have to drain it all. The rest of the water, or if you choose not to drain it, is going to get picked up in your fuel/water separator (which I hope you have one). You better have a sensor on it too, so you know when to drain it. Your worst option is to add a fuel additive to emulsify the water. Feeding water molecules to your injection pump is an all around bad idea, no matter how you look at it. I'll be happy to sell you a new IP when yours wears out from excessive water, but I don't like to see potential sales being generated by shortcuts and ***** moves when alternatives exist that will only save you money and increase your enjoyment of the truck.