Re: What gas do we use?
Most water filters will stop free flowing water just fine, but will not stop water that alcohol has absorbed (The proper term has escaped me). This isn't a problem when the engine is running, the problem is we let that water absorbed alcohol sit in out carburetors, intakes, valves, rings, and cylinders when the engine has been shut off. This water will then rust those parts.
I filled, sumped, and checked 100LL, diesel, and Jet-A fuel tanks at a small international airport fuel farm for two years. I also did the same for the fuel trucks. I learned about all I could about fuel in those two years. I am also a pilot who filled up his little airplane using pump gas. I performed the water check every time I fueled that airplane.
The water in fuel problem is caused mostly by condensation. The problem is greatly enhanced in a boat because of the vicinity to water and the higher temperature difference that water can create. A 70 degree fuel tank condensates when the bottom of the hull is immersed in 65 degree water and the dew point it 70+ degrees.
It is not possible to prevent all water from getting into boat fuel. This is why ethanol is not good for boats. (And most everything else for that mater)
