Originally Posted by Mullide
I found a small leak in on the bottom of my fresh water tank, which was an aluminum cube. I had to cut the salon floor, move the water heater and remove the tank to get a good look. The leak was on the bottom of the tank. Once removed, it was clear the tank was experiencing some widespread corrosion. With little to lose, we cut the tank open and found it was pitted everywhere and about to fail in a big way. I am now cleaning and painting the bilge, since everything is accessible due to the floor being cut away. I am looking for a replacement tank of about the same size (100 gal) but in plastic. It appears the life expectancy of the aluminum tank is 26 years in my case.
It might be easier and cheaper to make a new tank in place out of fiberglass if you have the access to do it. If not, when we need aluminum tanks made, we usually go to a local welding place that makes them to your specs.