Zero Waste RO

[banditpowdercoat]

Originally Posted by mark

Just wondering within Codes to be plumbing what is basically waste water back into the potable supply?

It's not that the waste water form a RO is bad, it's exactly the same water as your tap, because thats where it comes from. It's just called waste as the RO unit doesnt use it, and it is usually wasted down the drain.

You can drink the water coming form the "waste" line of your RO and you probibally wouldn't taste the difference from out of your tap

[sphelps]

Looking at some statistics this is how the average household water usage is distributed:

It would be nice to supply toilets with RO waste water since contaminants would be of least concern. Perhaps one could again use an accumulator and a check valve to send RO waste to cold water supply but only in bathroom(s).
Laundry is another good use but perhaps in a lower concentration to prevent water stains. I'm not sure how much of an issue this is so perhaps people who have used waste RO water in laundry could share there experiences.

[mark]

just because something is sold doesn't mean meets code

and no RO waste is not the same as source, has at least a higher TDS

[banditpowdercoat]

Ya but pretty much the same. Not like it's bad for you, and if blended back with the source water..

[sphelps]

Originally Posted by mark

just because something is sold doesn't mean meets code

and no RO waste is not the same as source, has at least a higher TDS

True but more than likely it does.

Of course it's not the same but RO waste water for some people will have a lower TDS than other peoples supply. For example if someone has a supply of 100ppm and a 4-1 waste ratio the waste water should be around 125ppm which isn't that much higher and once diluted into a highly used supply it's not much of a concern but ideally the waste water should only go to supplies that don't really matter so the user isn't forced to sacrifice water quality.

[mike31154]

In the not so distant future I plan on replacing my hot water tank with a 'tankless' or 'on demand' hot water appliance. Hot water tanks themselves are not the greenest technology these days since much of the time you are storing the water and keeping it warm or hot when it's not actually being used, wasting energy in the process. I'm pretty sure the system we're talking about here won't work with tankless hot water heaters, so for me it's already a non starter. I also have concerns about sending water that has been through the prefilters, thereby dechlorinated, back into the home's plumbing. TDS might not be a problem, but by removing the chlorine you've opened yourself up to possible bacteria issues, particularly when sending this waste water into a 'warm' environment. Finally, running RO systems for short bursts (as in only when the hot water tap is opened) is pretty well known to not be the best for your system. TDS creep is an issue since it generally takes a few minutes for the numbers to get down to acceptable levels after the system is pressurized.

My current procedure is pretty unsophisticated but it works fine for me and would say it is 'effectively' zero waste. I usually run the RODI to make at least 14 gallons for my top up containers, more for water changes. I have several large plastic barrels that I collect the RODI waste water in. In the summer it goes in the garden, in the winter I haul buckets to the bathroom and use it to flush the toilets. A bit of work yes, but simple without the issues I've mentioned above. Can't really use it in the washer since I have a newer front loader and they don't use very much water. May not work for everyone due to space constraints.

[banditpowdercoat]

Won't have to worry about the chlorine aspect, because the bacteria has allready been eliminates, none in the waste water. Plus, the hot water line is chlorinated to.

[mike31154]

Originally Posted by banditpowdercoat

Won't have to worry about the chlorine aspect, because the bacteria has allready been eliminates, none in the waste water. Plus, the hot water line is chlorinated to.

Good points, make sense and I guess my concerns are unfounded in that regard. I believe there have been cases, although rare, of 'Legionaire's' disease from people keeping their hot water tanks at too low a temperature for extended periods. This would indicate that even though bacteria is eliminated at one point, there's always a possibility of it returning somehow. They can be nasty little critters.

[Binare]

My ro unit is right next to my old school washer, its a piece of crap so I drilled a hole in the top, put an airline connector in it and crazy glued my ro waste line into it. Very high tech system I got goin on. The wife don't complain about stains or anything, but there again... I don't make enough water to fill it more then halfway before a loads ready to be washed. Something else for people to consider with top loading washing machines.