The Dark Side of RO water...
 

:biggrin: just kidding a bit with title ;) but for sure got your attention...

My question is more related to the amount of water wasted during the purification process... One of the negative points for RO systems is reported as the huge amount of water wasted... :shock: however, it is almost impossible to find data on how much water is "a huge amount" in this case...

so, my question to all of you using RO systems: How much water do you really need in order to produce... let's say 100L RO water? just an estimate is fine ;)

I am planning to buy a smal one (à la PuroSmart), however, I enter in conflicts with myself when thinking I am going to waste too much water...

This was discussed a while back and I recall there are lots of different specs. Some "waste" more than others. I don't think there's a simple answer to your question. For me it's a moot point. I have a whole house water softener (I have to with our water supply) and that is death to plants. I put salty water down the drain and the city takes it out in their treatment plant and discharges the treated water back to the aquifer. And then I live in a state surrounded by 4 of the largest freshwater lakes in the world.

Most systems in the range most of us would use (up to maybe 500 liters/day) fall in the 3:1 to 4:1 range, waste:pure.

Thanks ray! that's the kind of feedback I needed... I have now an idea of what is the waste I should expect... ;)

Ray is correct on the waste range. You can still use the waste water to water your outdoor plants, garden or lawn. Maybe that will help?
Peter.

Watts makes a Zero Waste unit that produces 25 GDP. The unit has a pump that connects to your water supply and returns the waste water back to it, eliminating all down the drain type waste.

Watts: FMRO4-ZW | 25 gpd 4 Stage, NSF® Certified Zero-Waste Reverse Osmosis System

If I'm not mistaken, "zero waste" systems are designed to be pumped back into your hot water supply, theoretically to prevent precipitation (although I doubt the minerals are concentrated enough for that to be an issue).