eSpring system by Quixtar is a very good - and very espensive ($600+ retail) - drinking water filtration system. But it DOES filter all contaminants and has a UV light that kills bacteria, viruses, cysts, etc.
eSpring Below Counter Unit
Haven't found anything similar out there, but there may be... Have to buy this through an independent distributor, of which there are couple of us here as MOCers. I am not trying make a sale, this is just the best w/f that I've seen for what your purpose seems to be, with a dependable system for killing bacteria and viruses. Maybe there are others out there that do the same?
Our pastor has had this system in his church for 2 years now. No one has passed out during his sermon, so must be OK...
I will be putting one in for drinking water, but in addition, I am also following Orv's system for a full RV water filtration system - showers, BR vanity.
Reverse osmosis is good, but very slow. Also, as William says, they are bulky and probably not practical for our Montanas. Maybe a huge Class A...