Hmmmmm.... It must have something to do with the source of your local water.
Here in L.A., a number of double blind tests indicated that most peeps can't tell the difference between bottled water and tap water, with tap water frequently having the edge for taste..... Must be all that gold still below the surface of the Golden State (not to mention a shortage of sinkholes and swamps leaking into the aquifer).
But still, we are the #1 area for bottled/filtered water sales..... Go Figure.
But, when you filter water you leave the contaminants behind in the filter and I don't see any method of killing off that residue. You wouldn't use the same water glass for a year without cleaning it would you?????
But I am sure I would have appreciated a system like that when I was at the bottom of the Grand Canyon or hiking the Pacific Rim trail, but for RV'ing, there are simpler and less expensive solutions.
BTW: what's a Prepper, is that like a Preppie on steroids? LOL