Bill, I have used Reverse Osmosis water for all my indoor plants since Sept 15, 2007 and I think if Kathy was to check way back in DG days she would find I put a little bird in her ear about R.O. systems. My system is considered a Zero Waste system as it returns the waste water back to your water system further down the line. I think typically, without this type of system, they waste about 4 to 6 gallons for every gallon they make. I don't worry about this as I have a ground water heat pump system to heat my house, so I pump out of one well and return the water to second well after it runs through the heating system, so the water for the R.O. systems is not even a drop in the bucket compared to that required by my heat pump system. As it is, I did not hook my R.O. systems as illustrated in manual but returned it to this same second well.
In the nearly 4 years that I have had the R.O. systems I have yet to replace the filters or the membrane, although I do think about it, but procrastination rules and the fact that my TDS meter (Total Dissolved Solids) only shows 2 parts per million. This would be well beyond the recommended time period, but if it ain't broke don't fix it. I have 250 plus orchids and a few other house plants which use about 3 gallons a day, give or take.
I used rain water for some time but it was a lot of hassle for me. Collecting it, carrying it, storing it and the quality many times left a lot to be desired. It is hard to believe how much crud can accumulate on your roof when you have asphalt shingles. If it wasn't a big rain to flush the roof and gutter system then what was collected smelled which got worse in storage and the color of the water could be quite unappealing. I found it caused a great deal of black mold and I developed a lot of bacterial problems.
The few old house plants that have been around for many years have responded very well and look much more vibrant after a few years of R.O. water. So all in all if my R.O. systems blows up tomorrow, I will ordering a new one same day.
Sorry Bill, this rant is a little longer than what you were looking for, but I thought would pass my experience along as well.
