Waste Water from RO/DI

[Cellenzweig]

Back to my first question, how are the people running the waste water to their lawn? black hose pipe with holes?? etc.... OR Just Teeing off the tube and branching out??? Please be specific

I was thinking about setting up some kind of drip system for my garden, just using standard drip nozzles from HD.

[Acroholic]

Originally posted by 481824
Back to my first question, how are the people running the waste water to their lawn? black hose pipe with holes?? etc.... OR Just Teeing off the tube and branching out??? Please be specific

At first I was using a drip hose ( a 50' garden hose with thousands of minute holes in it) from Home Depot when it was just RO/DI waste water.
Now I have a sink basin with hot/cold water, and the RO/DI waste water runs out through the sink drain via 2" pvc through my block wall, 90 degree elbow down to a PVC 4" French drain pipe ( a pvc pipe with hundreds of small holes in it) that is buried about 18" deep along the outside of my home.
This works perfect.
I also dump most of my used saltwater down this drain also, with no ill effects to any of the plants or grass along the drain. On the contrary, like Crash519 says, my grass is greener and fuller closest to the drain.
I'm not sure why everyone is having a problem with this, it just might be that the are speculating and actually have not tried it. I'm sure if you ask the people who actually do this, that you will be hard pressed to find someone who says that it is killing their grass.....Good luck....
you can check out my thread and see this from the inside of my equipment room......My tank thread

[Scuba_Dave]

I use Toro 1/4" drip hose - built in Emitters regulates how much water goes out ech drip point
100' winds its way thru my garden
Now that I have RO at the sinbk my garden will be watered more
I also plan on storing 55g drumps of water in the new garage for washer in the winter

[jdieck]

Originally posted by Mark426
No the waste water from an RO unit is not toxic, its just not very good at all for you or your plants. what’s left has ALL the metals/salts/etc. that was in the original water in a HIGHLY concentrated form. I am not sure what the actual efficiency of our home RO units are, but I for sure don’t want to use the waste water. Would be interesting to have the waste water tested…I bet we would be shocked

I think the impurity of the RO/DI waste water is overly overstated.

First of all it is water that has been already filtered from sediment, chlorine and organics as the waste watr has already passed trough the sediment and carbon filters.

Now some math:
Assuming your tap water has 200 ppm TDS of impurities and that the normal ration of Waste to product water is 4 to 1, that is for every 5 gallons you put in you get 1 of product water and 4 of waste.
A very efficient membrane cleans 99% of the impurities so you are removing 99% of the 200 ppm TDS in one gallon, say 198 ppm TDS, those get diluted to each of the 4 gallons of waste water or the waste water contains 198/4 = 49.5 ~ 50 ppm so the waste water contains 200 + 50 = 250 ppm of TDS. mostly carbonates.
Now it is not unusual to see tap water supply with over 400 TDS and still fit to drink so I think the term Waste in this case is used because most of us we just "waste" it but I consider it fully fit for plants, laundry, showering, dishwashing and really any other thing but drinking.

Now if you are really concern about reducing the waste, then just install a second membrane cartridge of the same capacity and type after the first membrane cartridge and your waste to product ratio will be reduced by half.
Connect the waste of the first cartridge to the inlet of the second and move the restrictor to the waste of the second membrane. Your production will double with the same amount of waste and it's TDS will increase by about 13 to 15% (say from 2 to 2.25 in our example above) so perfectly maneagable by the DI cartridge.
Note that depending on the cost of your tap water and the cost of the additional membrane you may not pay it back with the water saved in three years but you will be saving half of the waste volume.

[clkwrk]

our tap out here ranges from 500-800 tds in the desert

[jdieck]

Originally posted by clkwrk
our tap out here ranges from 500-800 tds in the desert

Sure, lots of minerals and salts