RO waste :S
- Thread starter austinpetemo
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gldnegle76
Member
Let me correct my first post in this thread. Didn't mean to say use it as drinking water (although I do use water that has been passed through the membrane (not rejected) for drinking water.
I do use the waste water in the washing machine, and on plants that I will not consume.
Just wanted to clear that up. I'm glad a lot of folks chimed in here; made me think of things I really hadn't considered before.
jeff@zina.com
New member
Keep in mind that the weekly wasted water from even a larger tank is still less than what goes down the drain in an average shower. Preservation is one thing, but the gray water use of a household is far higher than the waste rejected from a reverse osmosis membrane. And for most people, 80% or more of their water use is for irrigation.
If you're concerned, drain it into the washing machine or out a window.
Jeff
If you're concerned, drain it into the washing machine or out a window.
Jeff
d0ughb0y
Active member
since you are asking about breaking even, that implies your objective for saving the water is to save money, and I can tell you that by the time the membrane is be ready for replacement, you will still not be breaking even. water cost less than $2 per 750 gallons. You need to be saving 30 gallons waste water every single day for the next two years just to break even.
I stopped collecting waste water after I realized the cost of the water saved is less than $2. Not worth the hassle of family members getting angry at me because they could not do their laundry because they have to wait for the darn thing to fill up.
some may be saving the water for philosophical reasons, and that is fine.
Fishbulb2
New member
Just to be clear (so that people don't think I'm completely crazy). I don't believe that drinking RO waste water will instantaneously make anyone drop dead or give their families cancer or neurological diseases.
I just think for how small a cost of your total water bill RO waste water will constitute it's not worth any risk. Further more, the amount of water you consume will also be a small fraction of the RO waste you produce. So you are now really only recycling a few gallons of water a week by drinking it with the added risk of no longer knowing it's testing and quality assured by you local water facility.
If you really wanted to get "triple filtered" water for drinking from your RO unit without additional waste, you could simply disconnect the prefilter line from the RO membrane and drink that water. Now you would get sediment and carbon filter treated water without any of the RO membrane rejection and you would technically be using these filters according to their manufactures specifications. For me, that's way too much of a pain.
OK enough from me,
FB
I just think for how small a cost of your total water bill RO waste water will constitute it's not worth any risk. Further more, the amount of water you consume will also be a small fraction of the RO waste you produce. So you are now really only recycling a few gallons of water a week by drinking it with the added risk of no longer knowing it's testing and quality assured by you local water facility.
If you really wanted to get "triple filtered" water for drinking from your RO unit without additional waste, you could simply disconnect the prefilter line from the RO membrane and drink that water. Now you would get sediment and carbon filter treated water without any of the RO membrane rejection and you would technically be using these filters according to their manufactures specifications. For me, that's way too much of a pain.
OK enough from me,
FB
Fishbulb2
New member
The 2% come from the fact that most hobby grade RO membranes have a rejection rate of approximately 98%. So technically, you are not drinking that 2% TDS when you drink the waste water. That 2% would show up in the permeate water.
So again in our fictional example, if we have 100 TDS in the incoming water, we would now only distribute 98 TDS into each of the 4 waste gallons. So each gallon would go from 100 TDS to 124.5 TDS. The 2% I was referring to was to reflect the non-perfect rejection of the RO membrane and was just taken as the reported average from the DOW membrane spec sheets. That number will vary widely between membranes, manufactures, input pressure and other variables.
FB
gldnegle76
Member
I think I have "new ro/di owner syndrome". Seeing that waste line drain 3 times the water as my post di line, was just hard to swallow.:sad2:
However, based on the many things I've heard, this "illness" will pass quickly.
Not to change the subject but my tap water reads 165 ppm using a hm digital tds-3 meter. Water coming out of membrane (before di) reads 0-1 tds, based on inline tds meter on brs 5 stage plus system. That's an incredible rejection rate isn't it? Is that common for new units?
However, based on the many things I've heard, this "illness" will pass quickly.
Not to change the subject but my tap water reads 165 ppm using a hm digital tds-3 meter. Water coming out of membrane (before di) reads 0-1 tds, based on inline tds meter on brs 5 stage plus system. That's an incredible rejection rate isn't it? Is that common for new units?
Fishbulb2
New member
Hi gldnegle76,
Yes sometimes the easiest thing for "new ro/di owner syndrome" is to just mount the drain line into your sink drain and never look at it. I know it's depressing but it's more psychological and anything else.
That's a fantastic rejection rate and you should be able to retain it for long time as long as you continue to maintain the unit with fresh prefilters ect. This probably has very little to due with the fact that the unit is new but rather, you just got a really good membrane and you must have decent input water pressure I'm guessing. These membranes will keep their efficiency for many many years. Mine is about 6 yrs old and has not changed much. I once got a membrane with a rejection rate in the very low 90s out of the box. Randy Holmes Farhley in the Chem forum had his for 10 yrs so congrats.
One last thing. This website shows what will be removed and what will pass right through a carbon prefilter to help us determine what you might actually be concentrating in the RO waste line. I'm not familiar with these people or if they have an ulterior motive but it's all I could find on short notice via google. I was curious about this myself.
http://www.home-water-purifiers-and-filters.com/carbon-water-filter.php
The list of metals that will pass right through your carbon filter according to them is.
antimony
arsenic
asbestos
barium
beryllium
cadmium
chromium
copper
fluoride
mercury
nickel
nitrates/nitrites
selenium
sulfate
thallium
and certain radio nuclides
So this is a rough list of what we can assume will be concentrated by about 25% (from initial concentration) in your waste water. Your local treatment facility is probably trying hard to keep these low so they aren't likely common. However I wouldn't use this stuff for my family. Not worth it. If you want to reduce them from your tap water, drink the permeate not the waste.
FB
Yes sometimes the easiest thing for "new ro/di owner syndrome" is to just mount the drain line into your sink drain and never look at it. I know it's depressing but it's more psychological and anything else.
That's a fantastic rejection rate and you should be able to retain it for long time as long as you continue to maintain the unit with fresh prefilters ect. This probably has very little to due with the fact that the unit is new but rather, you just got a really good membrane and you must have decent input water pressure I'm guessing. These membranes will keep their efficiency for many many years. Mine is about 6 yrs old and has not changed much. I once got a membrane with a rejection rate in the very low 90s out of the box. Randy Holmes Farhley in the Chem forum had his for 10 yrs so congrats.
One last thing. This website shows what will be removed and what will pass right through a carbon prefilter to help us determine what you might actually be concentrating in the RO waste line. I'm not familiar with these people or if they have an ulterior motive but it's all I could find on short notice via google. I was curious about this myself.
http://www.home-water-purifiers-and-filters.com/carbon-water-filter.php
The list of metals that will pass right through your carbon filter according to them is.
antimony
arsenic
asbestos
barium
beryllium
cadmium
chromium
copper
fluoride
mercury
nickel
nitrates/nitrites
selenium
sulfate
thallium
and certain radio nuclides
So this is a rough list of what we can assume will be concentrated by about 25% (from initial concentration) in your waste water. Your local treatment facility is probably trying hard to keep these low so they aren't likely common. However I wouldn't use this stuff for my family. Not worth it. If you want to reduce them from your tap water, drink the permeate not the waste.
FB
Last edited:
gldnegle76
Member
Fishbulb2,
Thanks for the research, I had no idea.
BTW, I'm getting that rejection rate with 60 psi.
Thanks for the research, I had no idea.
BTW, I'm getting that rejection rate with 60 psi.
Acrotrdco
New member
Now you do have you ask yourself a question, what kind of water are you drinking now?
1. Tap water (boiled or straight from the tap)
2. Regular house-hold filtered water (e.g. Brita)
3. RO/DI pre-filtered water rejected by RO membrane
4. Bottled water
5. RO/DI filtered water from your RO/DI unit
6. Bottled mineral water
For those of you answered # 1-3, you're pretty much drinking the same thing. Granted #3 you'll have slightly more TDS than #1 and #2, but do you really know what's in that TDS?
It could be left over heavy metal that the GAC didn't absorb, or it could be minerals that's beneficial to your body.
For those of you answered # 4-5, you're drinking purified water, stripped of all heavy metals and containmates, but also minerals.
There're some research studies suggest that human body must absorb certain amount of mineral through water to sustain, so some folks would re-minerialize their purified water, but there're also some studies that say otherwise.
That's also the topic I've discusses with the folks at AquaFX during last MACNA about drinking pure RO/DI or bottled water.
For me, I've been drinking pre-filtered water for years - since the early days Brita type, which turns out to have absolutely zero effect on TDS after I tested it with a TDS meter, and I've since then switched to RO/DI pre-filtered water.
Granted, I'm not drinking a lot of water from that source since I dine outside mostly and most of my liquid intake is from bottled soft-drinks or likewise, so I know having just a cup of such water every now and then, isn't going to kill me. :rollface:
Porcupinepuffer
New member
Maybe not the water, but the SOFT DRINKS will kill you! You're just drinking piles of sugar. Quit drinking that crap. It rotts teeth, raises blood sugar that can lead to diabetes.
Acrotrdco
New member
Alright okay I'm not really drinking a LOT of that so don't worry but thanks for caring
I've been also very cautious about my health and well-being, so I know having a soft drink every now and then is okay, I've had my body check last fall and everything is in, should I say, working order, except a little high on LDL. :rollface:
merkurmaniac
New member
Another way to look at the consumption of RO/Di waste water would be to look at the total impurities consumed, rather than the concentration level. This means, your body is the filter.
So if you make a gallon of ROdi water and also produce 3 gallons of wastewater. You basically transferred all the impurities from the one gallon of super clean to the three gallons of wastewater. If you drank those 3 gallons of wastewater, your body is just getting the impurities that would have come from drinking 4 gallons of tap water. IMO, not a big deal.
I still don't drink it, as its inconvenient, but I think it would be insane to be hesitant to use the wastewater stream to water a garden producing veggies that will be consumed. A lot of that water would evaporate, leaving the salts and other impurities behind. This might be nothing more than the effect of watering a garden on a hot, arid day versus a cold, damp day, evaporation wise.
BTW, this is exactly how I use my RO waste stream. I dump it into my 230 gallon rainwater collection tank and let it sit. It has time for chlorine to leave, and I use it as top off water for my aquaponics system where I grow fish and vegetables. Its an outdoor pond that is constantly evaporating water, so its building up impurities over time, but they are also getting utilized by the plants. It hasn't rained in two months here, so I have had to use tap water to add to the tank. If I add 40 gallons and 10 evaporates over a month, its the same end result as using my RO wastestream.
So if you make a gallon of ROdi water and also produce 3 gallons of wastewater. You basically transferred all the impurities from the one gallon of super clean to the three gallons of wastewater. If you drank those 3 gallons of wastewater, your body is just getting the impurities that would have come from drinking 4 gallons of tap water. IMO, not a big deal.
I still don't drink it, as its inconvenient, but I think it would be insane to be hesitant to use the wastewater stream to water a garden producing veggies that will be consumed. A lot of that water would evaporate, leaving the salts and other impurities behind. This might be nothing more than the effect of watering a garden on a hot, arid day versus a cold, damp day, evaporation wise.
BTW, this is exactly how I use my RO waste stream. I dump it into my 230 gallon rainwater collection tank and let it sit. It has time for chlorine to leave, and I use it as top off water for my aquaponics system where I grow fish and vegetables. Its an outdoor pond that is constantly evaporating water, so its building up impurities over time, but they are also getting utilized by the plants. It hasn't rained in two months here, so I have had to use tap water to add to the tank. If I add 40 gallons and 10 evaporates over a month, its the same end result as using my RO wastestream.
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