I worked on all the Gun
Boats when they were coming out of production. They all had our watermakers installed on them. All the gun
Boats were suffering the same issues. Salt water in the tanks. Of course, Gun
Boat was all over us because they were certain that the watermakers were not working properly and sending salty water to the freshwater tanks. Yet every
watermaker I checked was working to spec. It turns out that the air vent for the freshwater tanks that are usually close to the water line were introducing salt water to the tanks by forcing it back up through the air vents and into the freshwater tanks. Of course, the Gun Boats were pretty fast and this would make sense. But usually this is not the case on usual cruising boats, but something to consider.