The fuel tank feed lines on my 30 year old Chris Craft come out of the bottom of the tank. The return lines go into the top of the tank. Usually, the top feed lines have a verticle pipe that goes down almost to the bottom of the tank, but not quite, presumably not to suck up accumulated water. My thirty year old tanks are iron and do not leak with hardly any rust outside, and since I feed from the bottom, probably no rust inside??(do not get any rust in my filters anyway. Any water I get in the tanks will go right to my filters (fuel water seperators) and not stay in the tank to grow things. I must, however, check my Racors often (especially on start up and when not having operated for awhile) and bleed out any water that accumulates, which is easy and simple to do. My last boat, I had for eleven years and 1800 hours, with black iron tanks and top feed lines, and I never had any water in my Racor filter. I guess what water I had is still in the bottom of the tanks. Of course I did use a lot of water absorbing additives during those years -- still do.