Can't fault your reasoning. We're using RO mainly for drinking, but I also use it to top-up nutrient sometimes.

Rain water is cheaper and collection is generally good for the waterways as it reduces runoff and erosion. Example: If you live in a suburb and get a major storm in the spring, I guarantee somebody has fertilized their lawn at the wrong time just prior. Everyone around me does and wonders why they have to mow twice a week in May. They also have likely applied a weed control. Pretty much everyone in the midwest has been hit by rain fairly well in the last few weeks. A lot of those toxins and fertilizers have run off into our waterways or downhill into someone else's garden (fortunately I live on a high point and use raised beds). The treatment plants in the midwest have yet to catch up on technology to deal with the extra runoff more pavement, houses, schools, shopping centers, and less trees equates to when you have a huge number of new developments. Fine by me. Our business thrives on overloaded motors at treatment plants (I sell motors and we perform testing on motors). Still, point is that rainwater collection helps in a number of ways and is just as good as RO.

If you are in the south and the drought severely beats your community yet another year straight, collection in the spring will greatly reduce the amount necessary to draw from the tap in times of scarcity. Especially if you draw from an RO system which uses up to 3 times the water the tap does. My brother (lives just outside of Georgia in Beaufort, but goes to school there) said that last year there were people talking about banning full house RO systems for that reason and limiting them to under sink only. Makes sense. They were on strict water rations for pools and lawns. Why not go after a bigger problem common in some new high end housing developments?

RO is very polluting and increases load on water treatment plants. It does nothing positive whatsoever for the water ways. They are expensive and increase the water bill. The water itself is great. Don't get me wrong. I just think it is definitely worth weighing the pros and cons. I have enough plants in the summer - soil and hydro - that they use more water than my family of 6 does in a month. If I used RO for the plants (we do for drinking), my bill would likely quadruple. It's not just the price of the RO system and filters. It's also the price of the tripled consumption one must consider.

All the problems you described can also happen with water temp fluctuations or just too high of water temps all the time. I'm quite sure they can also be affected by the quality of light due to the changed rate of nutrient consumption under poor lighting and the chemicals secreted by roots under varying conditions. These are called root exudates. I did an experiment last year on artificial lighting versus sunlight and discovered many things about the nutrient solution along the way. I used the same solutions and water in both and found very significant differences in the fluctuations of one set over the other. The high quality light (sun) set had very low reservoir maintenance while the low quality light set all had reservoirs that shifted daily out of optimum ranges. I made sure that reservoir temps stayed within 5 degrees F of each other (that was the best I could manage). I wasn't trying to study that, though. It was an interesting side observation of the experiment I was actually running concerning the effects of lighting on yield and foliage.

Sometimes the RO way is the only way. Apartment dwellers or those that live in those idiotic communities that have ordinances or HOA's against rain barrels due to aesthetics. Or maybe you live in a part of Colorado where collection is illegal (though that is being strongly fought).

You say you no longer have pH adjustments but the plants look better. How? They must be feeding or they wouldn't look better. Feeding = changes in chemical composition in reservoir = pH changes. Especially with tomatoes. More so with heavy feeders with huge fruit like the Cherokee Purple. Am I misunderstanding you?

Ro systems typically waste 4-5 gallons for every gallon purified not 3 as posted here. However if you equip the system with a permeate pump it will reduce that water waste by around 80% so the damage to the water bill and environment are much less and you get all the benefits of the RO system. I bought one that also adds cal/mag to the water automatically that is designed for hydroponics. http://www.theperfectwater.com/Tap-Master-Artesian-Hydro-Gardener-Pro-Remineralizing-Reverse-Osmosis-Water-Filtration-System.html

Considering the user name waterboy22, and that he just registered for this forum today (not to mention that this thread is 2 years old), I must say this last post sounds/smells to SUSPICIOUSLY like just a COMMERCIAL.

Hi Joe
This doesn`t hold true for me either as i use drain to waste. The res doesn`t alter until its empty, i find it much easier than chasing PH and EC on a daily basis :)

You say you no longer have pH adjustments but the plants look better. How? They must be feeding or they wouldn't look better. Feeding = changes in chemical composition in reservoir = pH changes. Especially with tomatoes. More so with heavy feeders with huge fruit like the Cherokee Purple. Am I misunderstanding you?

Not a commercial, but after taking a second look I could see where you might think that. "waterboy22" has been a favorite screen name since I was into aquariums years ago, and just learning about growing since its been legalized in my state, which also has hard nasty water...hence the need to learn about water purification needs related to hydro and this "year-old" post.

I have been researching Reverse Osmosis drinking water system. I want to have water filtration under kitchen sink. Do any of you have good experience with Reverse Osmosis that you have, and are willing to share tour thoughts?

RO filters are like inkjet printers - the company sells them at a small profit so that they can sell you refills at a huge profit. The cost to replace two carbon sump filters and the RO membrane is typically only slightly less than the cost of a new system.

Other than replacing the second carbon sump every other time instead of every filter change like your manual will say (first one clogs much more quickly), I don't know any way around the high cost of replacement filters. The rate at which you go through filters will depend somewhat upon your tap water; it's different for everyone. I would recommend that you at least buy your system from a seller who also sells the replacement filters. The only thing worse than paying a high price for replacement filters is not being able to find them at all.