# Zero Waste RO/DI systems?



## KurtG (Dec 10, 2007)

There is no such thing. The all produce brine by nature of how they work. You'd need a still or something.

The "zero" waste systems merely dump the waste brine back into YOUR main water supply. 

Some of the more (water) efficient units use a double pass system.


----------



## Dawn Haze (Feb 27, 2007)

Hi,
I have been casually looking at zero waste RO systems for a couple of years. I believe they work by plumbing the waste? line back into the hot water line. I would also be interested to see what anyone else knows about them.


----------



## Blackthumbwoes (Feb 27, 2007)

About the closest thing i've come up with is what a customer i spoke with years ago used to do. He'd use his RO water for discus and the "waste" water when into his african tanks as a drip water change. No really zero waste but at least it was all used for something in a fish tank.

Jason


----------



## neilfishguy (Dec 16, 2007)

use the waste for all non drinkinking water eg watering plants


----------



## EdTheEdge (Jan 25, 2007)

Ok so I guess the next question is "How much waste is produced?"

Thanks again.


----------



## mpodolan (Mar 27, 2007)

EdTheEdge said:


> Ok so I guess the next question is "How much waste is produced?"
> 
> Thanks again.


A properly functioning RO system should produce a ratio of about 4 or 5 to 1 of waste to RO water


----------



## waterfaller1 (Jul 5, 2006)

I have a friend that plumbs her waste out to her pond.


----------



## southerndesert (Sep 9, 2007)

I am running such a system and yes it pumps all waste water back into the system via the hot water line. Live in AZ and we are water conscious here...

Bill


----------



## dipan (Dec 3, 2006)

I'm also using the Watts Zero Waste RO system. It does plumb water back into the hot water line. You have to make sure the RO unit is not too close to the hot water heater otherwise backflowing hot water will end up in the RO filter potentially damaging it. I made a post on it here somewhere a while ago with my experience. A search for "zero waste RO" should turn it up.


----------



## epicfish (Sep 11, 2006)

Zero Waste RO System.

http://www.costco.com/Browse/Product.aspx?Prodid=10034720&whse=BC&topnav=&browse=


----------



## EdTheEdge (Jan 25, 2007)

Thanks for all the input. Epic's link was very beneficial.:thumbsup: 

I was just hoping that there was a zero waste system. I'd like to make 20 or so gals once a week. Nothing too important. Just thought I'd give it a try. I might still, but would find it hard to justify all the waste


> 4 or 5 to 1 of waste to RO water


. Too bad they aren't more efficient.

A little help here..... So what happens to the rejected water when it's plumbed into the hot water side? I don't use more than 50 gals or so of hot water on any given day. To make 20 gals would require 80 gals of rejected water where would that water go?


----------



## myhui (Jan 17, 2008)

epicfish said:


> Zero Waste RO System.
> 
> http://www.costco.com/Browse/Product.aspx?Prodid=10034720&whse=BC&topnav=&browse=


Almost the same as this unit:

http://www.labwater.com/shopdisplayproducts.asp?id=825&cat=Residential_Reverse_Osmosis_Systems

All they did in the zero waste system is to plumb the waste into the hot water supply. An alternative is to capture the waste in a water storage tank and use it for watering plants outside. I would much rather use the waste water outside than to have it rain all over my skin when I take a shower.


----------



## dipan (Dec 3, 2006)

myhui said:


> All they did in the zero waste system is to plumb the waste into the hot water supply. An alternative is to capture the waste in a water storage tank and use it for watering plants outside. I would much rather use the waste water outside than to have it rain all over my skin when I take a shower.


It's kinda more than just replumbing the drain line to the hot water supply. The system has to be engineered with the proper flow restrictor to account for the increased backpressure on the drain line when plumbing to the hot water side. The flow restrictor has to be chosen with this in mind, and not just based on the RO membrane GPD capacity as we normally do. A pump is also included to mitigate inefficiency caused by the increased backpressure as well.

As far as "waste" water goes, I would not be too concerned. The TDS of this water is only slightly higher than the source water ... figure around 20-25% higher. This is not really "dirty" water, though. It just has more of the minerals that the membrane rejects. Remember VOC's, sediment, etc (the real dirt) are eliminated from the water before it even hits the membrane.

Personally, if RO water requirements are not greater than the 20-25 gallons per day that this setup can muster, I think it's a great solution.


----------



## raddogz (Sep 26, 2007)

Not zero waste, but close

http://www.spectrapure.com/low_waste_systems.htm

http://www.thefilterguys.biz/water_saver_ro_di.htm


----------



## dipan (Dec 3, 2006)

raddogz said:


> Not zero waste, but close
> 
> http://www.spectrapure.com/low_waste_systems.htm
> 
> http://www.thefilterguys.biz/water_saver_ro_di.htm


Thanks for the links. Pricey, but looks to be really good ...


----------

