I am not fanatical about my water quality, and for many many years I used dechlorinated tap water. I bought an RO unit about 2 years ago, and finally installed it last January. I bought a Honeywell model 9100 made for human consumption. It produces up to 18 gpd, but can be modified to produce up to 50 gpd. It is a 5 stage system consisting of a sediment pre-filter, a carbon pre-filter, another carbon pre-filter, a TFC membrane, and a final carbon post-filter. In my research of other models, the TFC membrane is the same as is used on many of the fish tank models, and this is the most important part of the filter, as it is the stage that will remove most of the things in the water that you are looking to remove. It removes 99% of most contaminants, although nitrates are only between 92-95% (N- and N). IMO, this is good enough, and I don't know that most of these companies offering RO units for $200+ (mine cost $99 at Home Depot) do much better. IMO, for one of those 7 stage ones that cost $300 or so, you might as well buy 2 of what I have, filter your water twice, and then buy some TWPs and run the effluent through them. It'll cost you less, and I'm willing to bet the water quality would be superior. Not that I'm knocking any of these companies, but many people buy their RO water from the store because of the price of these units, and those store units are not any better than the one I have, they just filter more water per day.
