On my GS motorhome, the basement water tank leaked around the drain fitting. It could not be removed because they built the motorhome on top of it. It took multiple tries with a steep learning curve but plastic welding finally sealed the leak. It has been good for 2 years now...not a drip or drop. Good luck with yours.
Originally Posted by Pirate
Got the tank out and welded, 2 cracks, and a leaking, welded in fitting.
So far no leaks. It can be done!
Used a small torch, and LDPE, welding rod.
Tip. Practice on a storage container first!