RV Water Heater Stripped Threads On Drain

I have a water heater on my RV that I had to use a impact wrench to undo the drain plug. I read in one of your articles a reference to a thread chaser or tap. Could you please let me know where I can buy this tool. I've checked plumbing outlets, machine shops and big box home stores. I have checked with a couple of local RV super stores with no luck. Your help would be appreciated! Sonny B.

Sonny, if the NPT size of the threads is 3/4-inch, you can use a standard, tapered pipe thread to clean out the female threads. Just don’t cut too deeply; only enough to restore the threads in the tank. The tank threads will be a whole lot softer, so go slow! Here’s a link to a pipe tap that should work, though I'm sure any brand will do the trick.