Well, my fresh water holding tank had a big crack around the front corner, and was full of black sediment from years of rainwater leaking in past the filler door.
Get a new one, right?
I agree, except for the fact that it turned out that it was going to cost $520 plus tax to get it here to Ontario from Inland RV.
So .. back to the drawing board.
Brainstorm! Just replace it with a simple above floor custom one for half the cost, and hide it under the street side bed. We'd have to give up the storage under there, but there seems to be plenty without it.
Then reality set in. The filler port and door is designed for an under floor tank. (translation .... too low to adequately fill an above floor tank) And I don't want to get into moving the filler and the accomanying skin patching, etc.
So .. back to the drawing board again!
Found a place about 50 miles from here that commercially welds Poly tanks. $65.00 an hour for less than an hour's work!
Since the tank was cracked anyway, and had to be repaired, I cut a 5" square out of the tank using the crack as one side of the square. This hole was to allow me to clean the inside of the tank, and then get all the dirty water out! As you can see, the shape of the tank makes it impossible to drain it completely. Got it as clean as new, and disinfected it several times. Finished with several rinses, and we were good to go.
Took it to be welded.
Turns out Airstream uses some exotic blend of Poly. They couldn't weld it!
But they did get my clean-out square sort of welded back, but it was far from water proof.
So .. back to the drawing board AGAIN!
Bite the bullet and get a new one .... but wait! he tank is structurally ok now. I just need to get it watertight.
Enter TAP Plastic's Poly Bonder. (Sold in Canada as Mr Sticky's Wet Bond at Home Hardware)
I flame treated the areas of the tank I needed to repair,put a cote of the stuff on the seams and embeded some fiberglass cloth in the glue. Applied a second coat of the glue over top before it was set.
I just now finished the acid test. Filled the tank completely, plugged all the tubes and filler port and put my 230 lb self on the tank. Wiggled around, jiggled back and forth, pounced up and down (glad I was in my shop so the neighbors couldn't see!).
NO LEAKS. The repaired area(s) flexed right along with the rest of the tank. Now if this poly bonder stays pliable, and there is no reason to expect otherwise, I will be a happy capmer.
Total cost $25.00 for two tubes of the Wet Bond!