RO waste :S

[austinpetemo]

so i bought a RO DI unit so i could have some nice clean water for my nano. well i got it set up and running. however my parents dont like that the waste it puts out is several times the good output water. what can i do to use that water? we are on well water and they dont like wasting so much of it.

[gldnegle76]

Collect it as drinking water or put it in washing machine for next wash. Many people collect it and water their plants with it.
Also, you can buy membrane upgrade kits that could possibly get you good/waste ratio to 1:1.
Keep in mind, even the waste water from the ro is cleaner than tap water.

[oscar.millan]

Waste water simply has a high mineral content, but will have been through sediment and carbon, which as the previous post suggest is better than tap water.

Plenty of other uses, but I find the application of such uses to be a hassle. I ended up running my line to my garden and it's a done deal.

[ludiNano]

What membrane kits can get 1:1 never seen them but I want one

[Korrine]

a big long topic about this in Responsible Reefkeeping


http://www.reefcentral.com/forums/showthread.php?t=1931583

[Fishbulb2]

Send it down the drain. Yes it's been through a sediment and carbon filter but it is also more concentrated in everything it was originally designed to reject. So it's pretty much 4X concentrated in sodium, calcium, chloride, copper, lead, arsenic, cadmium and other charged molecules. Have you read about Chromium hexavalent in the news recently? This would be also be concentrated in the RO waste water.

RO waste water may have some contaminants removed from it compared to tap water but you should never state that it's purer, or safer than tap water. Anything rejected by the membrane is automatically concentrated in the waste and no longer monitored by any regulatory agencies or industrial standard.

Just dump the water. Don't drink it, don't use it for anything that will eventually end up in your body (like watering a garden).

FB

[Acrotrdco]

Waste water simply has a high mineral content, but will have been through sediment and carbon, which as the previous post suggest is better than tap water.

Plenty of other uses, but I find the application of such uses to be a hassle. I ended up running my line to my garden and it's a done deal.

Agreed - it's not exactly "waste water", the term is used incorrectly really, I'd rather call it the "pre-filtered water".

It's ran through pre-filters and trust me, the pre-filters in RO/DI units are 10x better than those "household water filter" you buy from home depot for under $100.

I collect those and use it in my automatic water boiler, good for coffee or tea in the morning.

[USC-fan]

What membrane kits can get 1:1 never seen them but I want one

Looking at getting one myself. But its $60. Thats a lot of water. Not sure you would never break even.

http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/ro-di-accessories/150-gpd-water-saving-upgrade-kit.html

[Fishbulb2]

Agreed - it's not exactly "waste water", the term is used incorrectly really, I'd rather call it the "pre-filtered water".

It's ran through pre-filters and trust me, the pre-filters in RO/DI units are 10x better than those "household water filter" you buy from home depot for under $100.

I collect those and use it in my automatic water boiler, good for coffee or tea in the morning.




This needs to be thought out. It is really really bad advice.

Yes the sediment filter will remove some sediment. So what? It's probably not harmful to begin with. Yes the carbon filter will remove chlorine and potentially some uncharged organic compounds (like pesticides). That's good. But everything else the membrane rejects, including all heavy metals, are now 400% more concentrated in your coffee, tea, drinking water, ect. It doesn't magically disappear.

FB

[Acrotrdco]

This needs to be thought out. It is really really bad advice.

Yes the sediment filter will remove some sediment. So what? It's probably not harmful to begin with. Yes the carbon filter will remove chlorine and potentially some uncharged organic compounds (like pesticides). That's good. But everything else the membrane rejects, including all heavy metals, are now 400% more concentrated in your coffee, tea, drinking water, ect. It doesn't magically disappear.

FB

GAC is known to absorb some heavy metal, so pre-filtered water before going through RO membrane contains less heavy metal concentration than tap water.

Most people I know just use tap water to make coffee/tea - or just use a regular household water filter like Brita, which is nothing more than pre-filters (sediment + GAC).

My measured TDS from tap water is around 62, and my pre-filtered water from RO exhaust is around 70-ish, yes it's slightly higher concentration but it's not 400% higher.

But then again, I don't know your tap water TDS, it might be lethal to drink pre-filtered water in your region perhaps :lmao:

[Fishbulb2]

In your case it's fine because clearly your RO membrane isn't working properly and it's not actually filtering out anything (since the waste basically equals the permeate water TDS).

For anyone with a functional unit or who has a unit that doesn't destroy matter, your RO waste water concentration pretty much equals your waste water to permeate ratio (minus the 2 or percent that goes through the membrane). Don't be fooled by smiley faces.


FB

[Acrotrdco]

In your case it's fine because clearly your RO membrane isn't working properly and it's not actually filtering out anything (since the waste basically equals the permeate water TDS).

For anyone with a functional unit or who has a unit that doesn't destroy matter, your RO waste water concentration pretty much equals your waste water to permeate ratio (minus the 2 or percent that goes through the membrane). Don't be fooled by smiley faces.

FB

My RO membrane is 3 weeks old. My RO water is 0 TDS and I run it through a DI unit anyway, also 0 TDS.

My RO/DI unit has a pump but it's not the highest quality one producing 1:1 ratio, so it's about 1:4 (1 part RO water 4 part waste), which means about 20% of my input pre-filtered water gets through the RO membrane.

I remembered I talked to the folks at AquaFX during the last MACNA show, and they were producing RO/DI units with 1:1 ratio, one of the guys there were a PhD candidate researching on water purification, I enjoyed the discussion and shared lots of interesting ideas.

Of the remaining 80% pre-filtered water that didn't pass the RO membrane, most of them are water molecules bind with other substance such as heavy metal, it's just that there aren't enough pressure to push them through the RO membrane.

So again after extracting the 20% pure H2O molecule from the pre-filtered water doesn't make your RO exhaust 400% higher concentration in impurities.

I don't know where you get the 2% from, I don't mind having an educated debate but you've gotta get your facts right.

[James77]

But everything else the membrane rejects, including all heavy metals, are now 400% more concentrated in your coffee, tea, drinking water, ect. It doesn't magically disappear.
FB

If your RO sysytem is like the typical one that "wastes" 4 gallons for every pure gallon, it is more like 20% higher in the metals and minerals the membrane rejects. The minerals from the gallon that was filtered- one fifth of the water that went in to make that gallon- would now be in the remaining 4 gallons.

[bobbychullo]

I would tend to listen to Fishbulb2. for one, he seems to know what he is talking about. two, Cambridge MA is well known as an intellectual center, that alone makes me think he STUDIES this stuff in SCHOOL since 3 out of 5 people in that area are college students and the rest are professors...

My RO membrane is 3 weeks old. My RO water is 0 TDS and I run it through a DI unit anyway, also 0 TDS.

My RO/DI unit has a pump but it's not the highest quality one producing 1:1 ratio, so it's about 1:4 (1 part RO water 4 part waste), which means about 20% of my input pre-filtered water gets through the RO membrane.

I remembered I talked to the folks at AquaFX during the last MACNA show, and they were producing RO/DI units with 1:1 ratio, one of the guys there were a PhD candidate researching on water purification, I enjoyed the discussion and shared lots of interesting ideas.

Of the remaining 80% pre-filtered water that didn't pass the RO membrane, most of them are water molecules bind with other substance such as heavy metal, it's just that there aren't enough pressure to push them through the RO membrane.

So again after extracting the 20% pure H2O molecule from the pre-filtered water doesn't make your RO exhaust 400% higher concentration in impurities.

I don't know where you get the 2% from, I don't mind having an educated debate but you've gotta get your facts right.

[Acrotrdco]

If your RO sysytem is like the typical one that "wastes" 4 gallons for every pure gallon, it is more like 20% higher in the metals and minerals the membrane rejects. The minerals from the gallon that was filtered- one fifth of the water that went in to make that gallon- would now be in the remaining 4 gallons.

Exactly. That doesn't increase the concentration by 400% now does it? :lol:

I would tend to listen to Fishbulb2. for one, he seems to know what he is talking about. two, Cambridge MA is well known as an intellectual center, that alone makes me think he STUDIES this stuff in SCHOOL since 3 out of 5 people in that area are college students and the rest are professors...

Interesting statistics!

So if I live in Massachusetts that makes me a MIT graduate, right? Cool, I need to pack my bags.

[liquidplumber]

By adding an additional membrane you can cut down on your RO Waste, BRS has an add on kit for sale and they have a nice instructional video as well.

http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/ro-di-accessories/150-gpd-water-saving-upgrade-kit.html

[c0mp|ex]

Sorry but Acrotrdco is right about this one. How is waste water 400% more concentrated? A 1:1 ratio of RO water to waste water would only be 50% more concentrated with minerals. A 1:4 ratio of RO to waste water would produce waste water much less concentrated than 1:1 ratio would.

[lilmonster]

I ran a line out my window and use it to water my lawn, works great, and the animals like it too.

[Fishbulb2]

Sorry, should be 25% more concentrated. If you have 100 TDS in one gallon of water, it will raise each of four waste gallons by 25 TDS. And yes, I would not recommend drinking the waste water of a 1:1 ratio RO unit either as that should technically be double the concentration.

If you have no idea exactly what is passing through the prefilters and concentrating in the waste, you should not be drinking that water. Water municipalities generally test and regulate what can be in your water and we have no idea how close some of these things are to allowed limits. No one should be recommending people to drink their waste water unless you are really looking at the water reports and are sure a 25% boost in anything is even acceptable. Use your RO water to get better drinking water for yourself, not worse.

Another point
People seem to just throw out TDS numbers now as if they are some measure of waters purity for drinking purposes. This is absurd as you have no idea what makes up that number. You can have one local that is supplied from a source high in harmless salts like Na, Ca, or Mg. This will have a high TDS and will pass drinking water standards. Other areas might be fed from a very low TDS region and have industrial seepage giving low TDS and high concentrations of questionable heavy metals (like chromium hexavalent that was in the news this past December). You simply can't through out a TDS number as some magic number to your water's drinking quality. It means nothing. TDS meters are best used to gave a membranes rejection rate and will loosely correlate how much DI resin you will run through before exhausting it (but still completely ignoring any contribution from CO2).

To original poster. Just look for ways to reduce waste if you can. The add-on membrane kit posted above can be a good start. If you use a pressurized storage tank for drinking water, then a permeate pump can save a tremendous amount of water. Lastly just use if for thing that won't end up in your body, like the washing machine. Good luck!

Thanks for the kind words bobbychullo. I'm actually a post doctoral research fellow at Harvard Medical School (in Boston).


FB


FB

[Porcupinepuffer]

Finally, I'm glad members with some basic math skills have came forward with correcting how much higher the concentration really is. Good lord! It would be about 15-30% more, depending on proper flow restrictor size, water temperature, etc... I would think it's safe to drink... But really, you shouldn't have told your parents about the rejection rates. I'm on a well, and I just let her reject all she wants. I don't pay for the water, but I do pay for the water pump to turn back on and off.

[Harry_Y]

What if it was just pumped Back to the well?

[gldnegle76]

Collect it as drinking water or put it in washing machine for next wash. Many people collect it and water their plants with it.
Also, you can buy membrane upgrade kits that could possibly get you good/waste ratio to 1:1.
Keep in mind, even the waste water from the ro is cleaner than tap water.

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]

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

[d0ughb0y]

Looking at getting one myself. But its $60. Thats a lot of water. Not sure you would never break even.

http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/ro-di-accessories/150-gpd-water-saving-upgrade-kit.html

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]

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

[Fishbulb2]

I don't know where you get the 2% from, I don't mind having an educated debate but you've gotta get your facts right.

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]

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?

[Fishbulb2]

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

[gldnegle76]

Fishbulb2,

Thanks for the research, I had no idea.
BTW, I'm getting that rejection rate with 60 psi.

[Acrotrdco]

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

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]

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:

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.

[njlpowell]

I fill my washing machine with it. Easy to do, and saves money for more corals :)

[Acrotrdco]

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.

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:

[alexwbush]

I just started running a mighty mite. Here's what I found:

Tap: 125ppm
Waste: 320ppm
Final product: 3ppm

I don't know what I would drink the waste...

[merkurmaniac]

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.