my new to me Lance camper had a leak in the drain nipple on the gray water tank. I bought a plastic welder from Harbor freight. I never did figure out what type of plastic it was, however if you look on line (you tube) you can easily find vids on plastic welding, and I used the "bridge" method with the plastic welder. It worked out pretty darn good, I backed that up with JB weld for wet. I have filled the tank and its been sitting wet for about a week now and no sign of any kind of moisture. My guess is time will tell if this was good long term fix or not.