What do you do with your RODI waste water?

[Idoc]

Right now. I just run the line outside into my lawn.

 

[Reefnman2]

I use mine as lawn water and also for the bird baths.

 

[KStatefan]

Mine down the drain to the river

 

[redfishbluefish]

I have a RODI system,3-stage, and I'm not understanding what the waste water is. Sorry if a dumb question, I just want things to go well for me.

A Reverse Osmosis membrane is like a very fine filter screen that allows pure water to pass through where the impurities are removed in the waste water. It is constantly flowing under pressure to get it to pass through the membrane. Typical RO systems have a ratio of 1:3 to 1:4 of pure water to waste water, so, as one example, for every one gallon of pure water you make, 3 gallons go down the drain. If you can capture this "waste" water, it can be used for other things, as mentioned in the number of posts in this thread.

Your RO unit has a line coming in with the raw water that first passes through a sediment filter, then to carbon block(s) and finally to the membrane. Included will be an auto shut off valve and a flow restrictor of some sort, and maybe a flush valve but coming out will now be two lines.....one that has the purified water, and the other the waste water. The purified water goes onto the DI resin where it removes that last little bit of impurities.

Hope this helps.

 

[User]

I’m using a 180gpd spectrapure double RO system with a single DI canister. Prefilter and carbon also, of course. I’m at a 2.4:1 waste : product ratio.

My incoming TDS is 36ppm. Suburbs Atlanta.

Do you think I could lose the RO and invest in a few more DI canisters to omit the waste completely? That would be pretty awesome.

 

[Adventures In Reefing]

That is exactly what I do. My waste water goes to my pool. I have never had an issue doing this and it replaces the evaporated water. I am running a salt water pool.

 

[JoshH]

I’m using a 180gpd spectrapure double RO system with a single DI canister. Prefilter and carbon also, of course. I’m at a 2.4:1 waste : product ratio.

My incoming TDS is 36ppm. Suburbs Atlanta.

Do you think I could lose the RO and invest in a few more DI canisters to omit the waste completely? That would be pretty awesome.

With 36 TDS I wouldn't skip the RO stage but what I would do is purchase new Capillary restrictors and adjust your Ratio to 1:2 or even 1:1.

 

[User]

With 36 TDS I wouldn't skip the RO stage but what I would do is purchase new Capillary restrictors and adjust your Ratio to 1:2 or even 1:1.

Is that 1product to 2 waste?

When I bought 18 months ago, the spectrapure rep told me this would be about as good as I could get with the best flow restrictor they had at the time, my tds and the pressure.

I’ll maybe call them next week and see if a new capillary restrictive can improve the ratio.

Thanks for the tip !

 

[DurbelMcDillett]

Lol... exactly... I'll hand everyone a shovel when they get here, and when we're done, they'll be a pool! ;Happy

I'm in! Send me the invitation!

 

[Chukthunder]

This makes me want to thread a wasteline through the dryer vent and water our roses.

 

[Cherie cook]

We water the side of the mountain....we’re dry here in Colorado! ;Smuggrin

 

[Paullawr]

I currently make my RODI water in my master bath. I accidentally closed the plug while making water. It wasn't closed for long. But I was shocked by how much waste water was in the tub. I hate that I'm wasting so much water. I know that I can get a more efficient RODI machine. I'm looking at putting in a pool next fall. I'm considering sending the waster water from the RODI machine to it. So that leads me to my question.

Has anyone found a use for the RODI waster water and if so, what is it?

Goes on the plants or in the water butt.

 

[amazongb]

I've wondered if this is possible. Picture two containers, one for source water, and the other for the filtered RODI water. Fill the source container with unfiltered water. Using a pump in the source water container, pump into the RODI unit, and let the waste water line return to the source container. This way, there's no loss. Water is moved from one container to to the other. I tried explaining this concept to my LFS, and he was not understanding what I was talking about.. I'm in Southern California, and we aren't under drought restrictions this year, but last year we were. For now, I let the waste run into my pool.

 

[redfishbluefish]

I've wondered if this is possible. Picture two containers, one for source water, and the other for the filtered RODI water. Fill the source container with unfiltered water. Using a pump in the source water container, pump into the RODI unit, and let the waste water line return to the source container. This way, there's no loss. Water is moved from one container to to the other. I tried explaining this concept to my LFS, and he was not understanding what I was talking about.. I'm in Southern California, and we aren't under drought restrictions this year, but last year we were. For now, I let the waste run into my pool.

That's more or less what dual membrane units do.....the waste water from the first membrane is sent to the second membrane. It appromately cuts your waste to good water in half. Note that the second membrane will have a shorter life. Some RO water experts suggest not using a second membrane unless your raw water TDS is very low.

 

[amazongb]

That's more or less what dual membrane units do.....the waste water from the first membrane is sent to the second membrane. It appromately cuts your waste to good water in half. Note that the second membrane will have a shorter life. Some RO water experts suggest not using a second membrane unless your raw water TDS is very low.

I have a dual membrane, and you're right, it reduces waste. What I'm suggesting is a zero waste solution as the waste water is sent back through the RODI unit. What I'm wondering is why this hasn't been tried, or it's just impossible due to how RODI filtering works..

 

[redfishbluefish]

First off, for most of us, water is cheap, or we aren't making extremely large volumes of water.. The second consideration is that each time through your RO unit, you continue to concentrate the TDS....for a 1:3 unit, that's 33 percent increase each time through. Now, a good membrane has a 98% rejection rate. So as the TDS climbs, the amount of TDS getting through will increase....burning out your DI prematurely. At some point the TDS will be extremely high.....

A more reasonable way would be to first distill the water (virtually zero waste, but you're consuming energy to heat) and then run that through DI.....virtually zero waste.

 

[JoshH]

Is that 1product to 2 waste?

When I bought 18 months ago, the spectrapure rep told me this would be about as good as I could get with the best flow restrictor they had at the time, my tds and the pressure.

I’ll maybe call them next week and see if a new capillary restrictive can improve the ratio.

Thanks for the tip !

Exactly or you could even step it up to a 1:1 product to waste ratio if you wish. If you did want to step into the realm of no RO membranes I would suggest a rather extensive DI setup with multiple single bed resins at first and once you figure out which type of resin depletes faster, focus more stages on that particular type. You can buy resin in bulk and save money there but it still might be a little pricey to run depending on how much water you make.

I have a dual membrane, and you're right, it reduces waste. What I'm suggesting is a zero waste solution as the waste water is sent back through the RODI unit. What I'm wondering is why this hasn't been tried, or it's just impossible due to how RODI filtering works..

EDIT: As mentioned above..

Recycling water over and over again would gradually increase the TDS of the water in the storage container which would eventually increase what gets through the membranes and into your DI stages which would decrease your DI life expectancy over time. Now this would greatly depend on your incoming TDS to being with. Your idea might actually work REALLY well for @neilp2006 who has what I would say would be borderline between even running a Membrane atall.

 

[James77]

I've always run it outside to any of my gardens. Water is not short of supply where I am, but it can't hurt to make some use of it.

 

[tdlawdo]

So true... the ground is incredibly hard here... Pretty sure it's going to require some heavy equipment.

now it just sounds like challenge that i have to accept...me against a back hoe...its on!!

 

[CincyRed]

I give it back to the fishes! I think our city recycles the water like 4x....so, it's not going to waste