I had trouble (and so have others) with the welding on the tank where the hot water comes out the bottom ( the exit nipple). I pulled mine out and cleaned and rewelded it. The reason there is a problem is quality control. The welder doing the welding did not stop and clean the slag off before completing the final connecting of the weld to itself. I used to be a certified welder for almost 40 years , so I know what causes it. It doesn't initially leak but after a while it will start a slow leak. This was on my previous 5th wheel not my current one.