Water Tank

""I discovered that the fresh water tank has a crack about 6 inches or so that runs vertically and is about an inch or so from a corner."

You can attempt to weld it with a soldering gun and a flat blade tip (either a tile-cutting tip or a homemade one).   But probably the easiest fix, assuming to can get access the cracked area, is to clean it well with rubbing alcohol and then apply an Eternabond patch. Matter of fact, I saw 6" x 6" Eternabond patch kits for $9.97 in the RVing section of the local Walmart just a few days ago.  If your crack is exactly 6" long, I'd suggest applying the patch diagonally--it's 8.4" that way. If the crack is longer than that, you may want to apply two patches overlapped.                                            Andy Baird                8/30/10