I know this seems a bit confusing, (to me) but OK then, here IS a toilet that can be connected to the fresh water supply and one should not have any grief about it?

And thanks for the clarification regarding lectrasan... I thought it was just part of the base of the toilet... I have never seen nor worked one, so not a clue there. I have seen and used vacuflush toilets... and thought they worked pretty darn well. Just a bit surprising for the next person... who has to wait for the vacuum to break.

What I meant by "what's the difference" was regarding how these work verses piston pump toilets with regard to how there can or cannot be cross contamination. I'm not sure how they are "perfectly isolated" from the flush water/fresh water source.

According to the info on the site... "Water control solenoid valve with anti-siphon breaker to prevent contamination of potable water supply." OK so there is that anti-siphon breaker... can it ever fail?