Adding water to fuel is a bad thing, but we northerners had to deal with it so on occasion we added fuel line anti freeze which was basically alcohol. The water with its antifreeze would work its way through the system and if the concentrations reaching the engine were small it would pass though the engine. The engine would stumble a little if a big slug of water reached it all at once.
The water could enter the fuel tank with fuel when refueling, but a lot of it was the result of humid air being drawn into the tank and the moisture content condensing.
There is not a pilot on this forum that is not sensitive to how serious water in the fuel is.
Ironically, around the mid sixties Olsmobile produced a Cutlass with a turbocharged engine and it had water injection to control the burn and prevent detonation.
Growing bacteria and getting moisture in Jet fuel is dealt with in aviation with an additive such as Prist.