8e3k0's procedure works for the hot water, too.
I had this happen to me once. The hot water heater gets a condition called "sulphur water", where running the hot water gets a kind of sulphur smelling stink to it. It was explained to me that there is nothing bad about it and there's a particular natural bacteria that causes it, but it STILL STINKS and I don't want to use it in that condition. In my case I had to fill the fresh water with 5 gallons of water to about 3/4 cup of bleach, then run the hot water until I could smell bleach at all hot water taps. Let sit for a few hours, then drain the fresh, refill completely flush everything until you smell no more chlorine. That's a lot of water, but it works. I have not had a problem since.
This took me pretty much all day, but we were at the CG, hooked up and finished everthing A-OK.
This may have been caused by an old water filter, or bad luck, but since then I am religious about changing them out and using a filter EVERY TIME. I also relieve the hot water tank pressure when I return home.