laffman,
Sounds as if your Campground has high levels of sulphur in their water supply. I would not only turn off the HWH when you leave the CG but consider draining it.
I found this online from an RV tech(
link):
"Rotten egg smell in the hot water.
One of the fun things about RV repair is it is very common to find varying opinions about solutions and caused for the same basic problem. I have found three different techniques to this problem. The cause always seems to be pretty much same however.
Cause: Sufficient amounts of sulfur in the water to produce an odor. This is caused by the electro-galvanic action of either the special 15% thickness of the type 7072 aluminum (pure aluminum and zinc) that is fused to the inside of Atwood tanks since 1988 or the anode rod in the Suburban. Bacteria in either brand can also cause it.
Solution:
Step 1 : Turnoff the water heater and let water cool if need be.
Step 2 : Drain and flush the tank. By flush I mean let fresh water run through the tank quite awhile and get out all the sediment that can settle in the bottom of the tank. The agitation action of the water coming into the tank should help unsettle and flush the sediment. Compressed air can also agitate the sediment or you can use a bent stiff wire or brush and go in through the drain hole to stir things up. If you do this be not to damage the threads. The primary objective here is to get the sediment out. I might also advise to be certain the water you use to flush does not have a sulfur odor. Keep the drain hole clear as the sediment can stop it up."
The subsequent steps involve sanitizing the system either by means of vinegar or chlorine.
