tenbear: ditto. I do the same thing.
Ron is right that bleach is a little hard on rubber, but I really don't think it probably has a probability of damage to the seals because they are mostly not really rubber but other materials. In all the years I have done this it never has been a problem.
After I dump and drain all the bleach water, I hook up the hose, fill up the tanks and completely flush out 95% of that "bleachy" smell. If it ain't out and my wife sniffs it in the shower......well, let's just say it isn't a pleasant day. I make sure also that the hot water tank is completely sanitized in the process and completely cleansed of bleach. I overkill, to be sure, but I feel better about it.
When you pull into WhoKnowsWhere and hook up to the water, what assurance to you really have of the safety of the water? Commercial campgrounds seem to me to be especially problematic. I have no idea if there has been backflow from someone's hose into their system.
That is why we spend about a buck a day on bottled water. The cost is equivalent to a quart and a half of gasoline.
Paul