What's the tank made of--metal, plastic or FG?
If it's metal, you might as well just build a new tank, 'cuz the first leak(s) in any metal waste tank is/are always only the FIRST leaks as urine continues to eat through the metal..first in welds at seams and fittings, then the sheet metal...eventually turning the tank into a colander.If the tank is plastic, nothing yet exists that bonds to polyethylene permanently, so at best you'd only be staving off the inevitable for a year or two, likely less time than that. Heat welding--IF you know how to do it correctly--can mend some cracks in some locations, but not all.But if the tank is fiberglass, you can prob'ly repair it with any good epoxy. Tensile strength isn't really an issue, though...'cuz tank walls should be thick enough to support the weight of the contents without flexing or bulging.Bottom line: If your tank has failed, I think most people will agree that replacement instead of repair is the only good option no matter what it's made of, and will most likely be the least expensive solution.