Reusing rodi waste water?

Reef kid · Feb 20, 2016

After I got my RO system set up I was horrified by the waste. Would it be possible to just have this stuff go right back into the unit to filter again? What would be the problem with this because I can't imagine others haven't thought of this

ermartin · Feb 20, 2016

Your better off running it to a rain barrel or into your plants. I personally have a water feature that it automatically tops off whenever i make water... There are a few threads out there discussing this with lots of great idea's

AZDesertRat · Feb 21, 2016

No you can't run it back through without boosting the pressure back up to 60-65 psi. Even then it would only work for a short time and plug up as the solids become more and more concentrated.
Send the brine down the drain to be recycled and used over and over, it is not wasted.

Reefrookie220 · Feb 21, 2016

I know a rather large breeder that uses his waste water for his cichlid breeding tanks. They love it.

saltyfilmfolks · Feb 21, 2016

AZDesertRat said:
No you can't run it back through without boosting the pressure back up to 60-65 psi. Even then it would only work for a short time and plug up as the solids become more and more concentrated.
Send the brine down the drain to be recycled and used over and over, it is not wasted.

is there a concern for lawns and plants AZ?

AZDesertRat · Feb 21, 2016

The brine TDS will be 20-25% or more higher than your original tap TDS. If you have landscape or lawn that doesn't mind that then it would be OK.
If you run the waste to a barrel, container or directly to a lawn make sure you have an air gap in the line to prevent any back siphonage so it meets health and plumbing codes.

For us in Phoenix or the southwest with high tds and salts in the tap water it's probably not the best idea and I sure wouldn't put it in my swimming pool.

MPSchenck · Feb 24, 2016

I've been researching getting a RO/DI unit and recently saw a vid on YouTube where the guy had the waste water going into his washing machine and he said he washed his towels in the waste water.
I'm thinking of plumbing mine into my laundry room for this very reason.

redfishbluefish · Feb 24, 2016

I have a 55 gallon drum that I use to collect waste water and use it for the washing machine and watering plants. The slight increase in TDS has no impact on washing or watering plants. They probably like it!

AZDesertRat · Feb 24, 2016

Two issues with filling your washing machine are it does not work with modern front loader machines and with top loaders they only hold a few gallons before they overflow and flood the laundry room. Make one gallon of RO/DI and you have 3-4 gallons of brine so you really need to pay attention to divert it somewhere else once the washer is full.

redfishbluefish · Feb 24, 2016

I have a toploader that I do need to "fool" to fill it with water. If I simply put water in first, it detects this water and pumps it out. It's a new machine, and my old machine didn't have this feature. So I have to actually start the washing machine, and as soon as it starts to fill, I open the lid (which stops the filling), and now fill it up with waste water.

Now I do a second fill when it's ready to rinse. With my machine, at 26 minutes, it starts its rinse cycle. I once again fill it up with waste water, and I've now pretty much emptied that 55 gallon drum.

The slight increase in TDS is still way below some of the nightmare levels I've heard from some folks. Again, no impact on the machine or watering. For the sake of putting down theorical numbers (I've never measured it, because it's insignificant), an incoming TDS of 150, with a 4:1 ratio of water making, would result in waste water at 188. No big deal when you've heard of folks at normal TDS of 500 or more!

AZDesertRat · Feb 24, 2016

I am one of those folks. Phoenix area TDS varies between 500 and over 1600.

hybridazn · Feb 24, 2016

I have my waste water fill my 150 gallon turtle tank. For water changes and top off. I coordinate water changes with filling the rodi container

redfishbluefish · Feb 24, 2016

Ouch! I use to consult for environmental stuff, and back in the day, and if my pea-brain remembers, they didn't have a water quality standard for TDS.....they just had a "recommended" level....and I want to say it was in the 600-700 range....but it's been too long, so I'm not sure. At that level of TDS, dead people in Arizona are halfway there to being petrified! I've got a kid in Scottsdale....I need to tell her not to drink the water!

Reflective · Feb 24, 2016

Definitely tell her not to drink the water! My sister-in-law and their family had all sorts of health problems when she lived in AZ, then after moving to UT they have all seemed to disappear. Blamed it on the water.

AZDesertRat · Feb 24, 2016

There still is no MCL for TDS since it is not a measurement of anything specific. Could be anything.
I am an environmental consultant, spent 30 years in municipal water and the last 10 as a consultant.

AZDesertRat · Feb 24, 2016

I would put our water up against about anywhere. The only thing I don't like is the hardness which fouls plumbing fixtures, hot water heaters and evaporative coolers pretty fast.
Now you know where all the minerals from the Grand Canyon went!