What is the difference? I am not planning to get an RO system and I can't collect enough rainwater to use it exclusively.
i use a small countertop R/O filter that attaches to the kitchen faucet. HIGHLY recommended for a small collection and also inexpensive.
Hmm, usually the ones that attach to you kitchen faucet (at the faucet end, not under the sink) are carbon and sediment only, not true Reverse Osmosis (like the Pur and Britta faucet filters). But I could be wrong. RO systems usually have a couple "stages" of prefilters before the RO membrane. All these stages would be a bit cumbersome to have on the kitchen countertop.
I know what you are saying--I was a little unclear in my post.( what, you all can't read my mind?)
The filter unit is attached through tubes, not directly on the faucet itself. There are 3 pre-filters (carbon, sediment) plus the R/O membrane and finally DI resin. It is the same kind of R/O filter you can also install under the sink by tapping directly into the cold water supply. That is the best way to set these up... But since we rent i use a faucet adapter and place the unit on a shelf next to the kitchen counter. Yes, it is a little ugly and it is big but the sacrifices we make for our plants...
I guess the point I was trying to make is these R/O units can be had for fairly cheap and are a great solution for a relatively small orchid collection (I have about 200 plants).