This has been a good thread to learn about RO. I had no idea that RO produces only 10 - 25% and wastes the other 90 - 75% of the water it treats. Does that really mean people with whole house RO systems are dumping most of their water down the drain without using it?
REVERSE OSMOSIS
- Thread starter rScotty
- Start date
- Views: 2586
OP
rScotty
Super Member
- Joined
- Apr 21, 2001
- Messages
- 9,573
- Location
- Rural mountains - Colorado
- Tractor
- Kubota M59, JD530, JD310SG. Restoring Yanmar YM165D
That's good you checked for a leak too, since that was my next suggestion. I guess it's a good thing you weren't drinking drain water all this time.
Well, I had some time to think about that and realized that even if I had, it would have been the same water that I'd been drinking for the past ten years before putting in the RO. I've got a call into GE's tech dept., hope I get the right person.
rScotty
OP
rScotty
Super Member
- Joined
- Apr 21, 2001
- Messages
- 9,573
- Location
- Rural mountains - Colorado
- Tractor
- Kubota M59, JD530, JD310SG. Restoring Yanmar YM165D
Not all of the systems dump the same amount of water, but all seem to dump some. The GE claims 10% flow efficiency; it is designed to dump 9.something gallons for every gallon of RO made. I've heard that some modern systems are more efficient. My guess is that a certain amount of waste water is necessary to flush the RO filter and maintain the concentration gradient...but that's just a guess.
Just as important is that the waste water flow be shut off when the RO tank is filled. The GE has a valve that does that, so the waste water doesn't continue to flow all the time.
BTW, I'm not convinced that the RO waste water has to be wasted. It's true that most of the systems are designed to put RO waste water into the outflow from the house right along with all the systems that dump or flush "used" water, but that seems to be plumbing convenience. I suppose it could be plumbed for watering plants or other purposes.
rScotty
ScottyChip
Silver Member
Hi rScotty
Great topic and I was going to suggest the same to check your lines for reversal, but since that is not a problem my next suggestion is that maybe your RO membrane is busted, or full of material and its efficiency is reduced and you are getting your system contaminated with the RO waste water. The membranes will fail or get plugged depending on the amount of material that has to be filtered. It is a very very fine sheet of material with really small holes on the microscopic scale that is wrapped around a central core that requires a high pressure to force your water through, then the contaminates that will not go through are washed away with water, hence the waste water.
I work in a analytical lab and we use RO systems to clean (polish) our city water so that we have no ions or contamination what-so-ever. Some manufactures of consumer systems will run the water through a charcoal filter or other type of filter after the RO membrane to add back in some of the ions removed to improve taste and as one person mentioned earlier to make it less corrosive (well it is not really corrosive, it is just that it has no ions and the pH is usually slightly below neutral or between 6-6.8), also the final filter will remove any VOC's (volatile organic compounds) they may be in your water. Softer water or water with lots of minerals and other ions will be harder on your RO membrane and it may need to be replaced earlier than suggested. The RO membranes in the consumer units is usually much smaller than the commercial units, but they both work the same way.
The other concern with RO systems especially for those of us on wells is the amount of waste water produced and the average system will waste 4+ gallons of water for every 1 gallon of water produced, hence why most people only treat drinking or cooking water and not the whole house. I would look at the systems you can get at your local Costco, Watts and Brondell, they both get good reviews, are relatively inexpensive and Watts offers the traditional and a zero-waste or their version of zero-waste which just dumps the waste water back to your hot-water tank so it can be reused as hot water. Not sure what happens to your hot water tank in the long term with all those extra minerals and other waste, but I am sure they would not be selling if these units if it caused long term problems. The other good thing about buying from Costco, is if you are not satisfied you just bring it back.
Hope this helps and this is a great discussion. I am looking to go down the same path as yourself, my well water has clear iron, and a number of other minerals. The reason I have not made the leap yet is the amount of waste water produced and potentially running my well dry. But really, I think I am being overly cautious, my well has good flow and capacity.
Scottychip.
Great topic and I was going to suggest the same to check your lines for reversal, but since that is not a problem my next suggestion is that maybe your RO membrane is busted, or full of material and its efficiency is reduced and you are getting your system contaminated with the RO waste water. The membranes will fail or get plugged depending on the amount of material that has to be filtered. It is a very very fine sheet of material with really small holes on the microscopic scale that is wrapped around a central core that requires a high pressure to force your water through, then the contaminates that will not go through are washed away with water, hence the waste water.
I work in a analytical lab and we use RO systems to clean (polish) our city water so that we have no ions or contamination what-so-ever. Some manufactures of consumer systems will run the water through a charcoal filter or other type of filter after the RO membrane to add back in some of the ions removed to improve taste and as one person mentioned earlier to make it less corrosive (well it is not really corrosive, it is just that it has no ions and the pH is usually slightly below neutral or between 6-6.8), also the final filter will remove any VOC's (volatile organic compounds) they may be in your water. Softer water or water with lots of minerals and other ions will be harder on your RO membrane and it may need to be replaced earlier than suggested. The RO membranes in the consumer units is usually much smaller than the commercial units, but they both work the same way.
The other concern with RO systems especially for those of us on wells is the amount of waste water produced and the average system will waste 4+ gallons of water for every 1 gallon of water produced, hence why most people only treat drinking or cooking water and not the whole house. I would look at the systems you can get at your local Costco, Watts and Brondell, they both get good reviews, are relatively inexpensive and Watts offers the traditional and a zero-waste or their version of zero-waste which just dumps the waste water back to your hot-water tank so it can be reused as hot water. Not sure what happens to your hot water tank in the long term with all those extra minerals and other waste, but I am sure they would not be selling if these units if it caused long term problems. The other good thing about buying from Costco, is if you are not satisfied you just bring it back.
Hope this helps and this is a great discussion. I am looking to go down the same path as yourself, my well water has clear iron, and a number of other minerals. The reason I have not made the leap yet is the amount of waste water produced and potentially running my well dry. But really, I think I am being overly cautious, my well has good flow and capacity.
Scottychip.