Just some information. I just looked at my 105 gallon Marathon. Test pressure is 300 and working pressure is 150. If you go to the virtual tour on the Marathon site, you will see that the polyethylene molded tank is not the tank but is just the outer jacket. The tank is fiberglass with a polybutylene inner liner. So either the fiberglass failed or more likely the swaged fitting of the brass port to the fiberglass. The moral of the story is that anything man made can fail. So I guess I need to drain my Marathon and get a drain pan with outlet under it.