I had the rotten egg smell coming from my hot water lines. Drained the hot water tank, added bleach to the water tank, flushed out the lines. Now I need to drain and refill the water tank. I looked around the perimeter of the motorhome and I do not see a drain plug or valve. Does anyone have an idea where it is? I believe I can see the grey colored tank in the center of the chassis, but without crawling totally underneath I do not see the plug.