How do you plumb to reuse RO/DI waste water??

piscivorous

piscivorous

New member
I have seen that a few of you guys use the "waste" water that is filtered through your RO/DI units for washing clothes, and doing dishes etc. I am curious how you have plumbed things to be able to do this? Do you have a holding tank of some kind of the waste water?? I've got a large enough water bill at the moment as it is...I don't want to be adding a ton of wasted water to this bill. If I could figure out a way to take advantage of the RO/DI waste water for things like the clothes washer etc. that would be great.
 
I wired in a selonid on the washing machine to run my RO/DI unit so when the wasing machine fills up the Ro run's then i just routed the waste water into the washer tank. Ill get some pic's for you.
 
That sounds like a great idea. I've heard of people somehow collecting it and using it for watering their garden.
 
Anyone else have any suggestions on how to utilize all of the wasted RO/DI water for your washing machine or for taking showers etc.????
 
The Permeate Pump sounds great, but I don't understand how it works. Is it just reducing back pressure from a tank? If it really reduces waste by 80%, you "could" get 1 gal pure water with 0.8 gal waste instead of 1 gal pure with 4 gal waste

I found another link

link

"3. A slight increase in TDS (total dissolved solids) reading under normal household operation. "
 
I like that zero waste system....I wish I could get a better picture of it...or see one in person. I like to know the principle behind it...I'm sure you could build one for less than $215. THAT would be a nice setup though.
 
I found this as well....I am not familiar with the "brine" water..is this really not something you would want to wash your dishes/clothes/hands with???

Reducing Reverse Osmosis Water Waste:
Compare "Zero Waste" vs. the Permeate Pump

Overview
Wastewater is a by-product of the reverse osmosis water purification process. Even the best residential reverse osmosis systems will make almost 4 gallons of water brine for every one-gallon purified, while lower grade systems can waste as much as 8 gallons of water per gallon purified. Recently some companies have introduced "zero waste" reverse osmosis systems, which do not waste any water. These systems still produce brine water as a by-product of the reverse osmosis process, but can labeled as "zero waste" systems because the brine water is recycled; not flushed down the drain as wastewater.


The "Zero Waste" Reverse Osmosis System Process
"Zero Waste" reverse osmosis systems come in two basic types. The more advanced types of "zero waste" systems eliminate water waste by pumping the brine water into the hot water plumbing instead of down the drain. The drawback to this design is that the brine water injected into the hot water line can be discharged from your kitchen sink faucet on your hands, cooking, dishes, etc, and into your dishwasher. The less advanced types of "zero waste" systems will pump the brine water back into the cold water line that feeding the reverse osmosis unit. The downside to this design is that the additional concentrated brine water in the feed water will force the reverse osmosis system to work harder and wear down the system components faster resulting in more frequent filter changes and overall shorter system life than a comparably equipped standard reverse osmosis system. Both systems are effective at eliminating water waste but their downsides are significant.


The Permeate Pump: Alternative to Zero Waste?
While a permeate pump equipped reverse osmosis system will still waste water, it can reduce the amount of wastewater by up to 80%. Furthermore the permeate pump equipped reverse osmosis system disposes of the brine water rather than injecting it back into the system where it can end up on your dishes, cooking, or back in the filtration system reducing system life. The permeate pump brings additional benefits beyond reduced water waste such as faster water production and prolonged system life when compared with a similarly equipped "zero waste" system, because of the permeate pump's efficiency improvements. (more information on permeate pumps)


"Zero Waste" Pros & Cons

Upside No water waste
Downside Brine water discharge on hands, cooking or dishes, orShortened system life and more frequent filter changes

Permeate Pump Pros & Cons

Upside Improved system life and efficiency
Upside Improved system recovery speed
Upside Improved reserve tank holding capacity
Downside Some waste water
 
I'd like to know what typical waste water savings you would get with the permeate pump. When I make water for water changes, I turn the tank off normally anyway so backpressure isn't a problem.
 
I just run my Ro wate water into a predrilled African Cichlid tank. That's their only filtration is a constant water change. They love it!
 
<a href=showthread.php?s=&postid=6656684#post6656684 target=_blank>Originally posted</a> by frank10
The Permeate Pump sounds great, but I don't understand how it works. Is it just reducing back pressure from a tank? If it really reduces waste by 80%, you "could" get 1 gal pure water with 0.8 gal waste instead of 1 gal pure with 4 gal waste

I found another link

link

"3. A slight increase in TDS (total dissolved solids) reading under normal household operation. "
Click to expand...

the permeate pump works like a water hammer. a water hammer is caused when the water is quickly shut off. this results in a sudden and brief increase of water pressure. this results in a bang, hence the term "water hammer". that increase in pressure can be bad for your pipes possibly causeing them to burst. that is why one may install a device to prevent water hammers.

the same principle is used with the permeate pump. as well as numerous pumps used throughout history. these pumps are also called ram pumps. here is an example of one and how it works. http://en.wikipedia.org/wiki/Ram_pump

the equation force=mass*excelleration can be used. when the water moves faster its force (pressure) increases but the force is only excerted when it comes in contact with something (the valve being shut off). there are some flaws in this description but is gives you the jist of how it works.
 
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On further investigation, it appears that the permeate pumps only make a big difference if your RO is filling one of those pressurized holding tanks, like goes under your sink.

The idea is to keep the pressure differential the same across the membrane as the pressure tank fills. But if you just dumping your RO into a trash can (or similar container) like me, then there is no back pressure on the output line like there would be with a pressure tank. So I don't think these will help.

But the zero waste system still has merit. It is true that you would be pumping the waste back into your household water, but it is into the hot side of the system. Plus the water you are putting back in is leftover water from what came out of the system to begin with.

True it has a bit higher concentration of solids but I don't think it would be anything to worry about. Like I said it is going into the hot side and it is diluted with the other water in your plumbing. Since my setup is close the my water heater, most of it would go back into there. I just wish they were a little less expensive.
 
also a permeate pump is good when house hold water pressure is low. it increases pressure on the membrane. allowing more water through per water wasted.
 
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what about the claims of reducing up to 80% of the waste (brine) water? is the RO system more efficient (less wast) at higher pressures?
 
also a permeate pump is good when house hold water pressure is low. it increases pressure on the membrane. allowing more water through per water wasted.
 
>> what about the claims of reducing up to 80% of the waste

I think this is because the waste increases significantly as the pressure in the holding tank increases. That is because of the loss of pressure differential across the membrane. The RO unit is trying to output against more and more back pressure from the holding vessel. When the pressure tank is empty, the RO unit has almost no back pressure so the RO unit is fairly efficient. The pressure in the tank increases as it fills and the RO rapidly gets less efficient and produces less product water and more waste water. This is when the permeate pump will make a difference by maintaining the original pressure differential as the tank fills.

But if you are not outputting into a pressurized holding tank, then there is no decrease in pressure differential as the container fills. There is no back pressure. The pressure differential across the membrane would remain constant. So your RO unit should maintain the same efficiency the whole time it is running.

I suppose it could help with low household pressure. They also make pressure boosting pump specifically for that.
 
are these ratios of 1:4 (pure:waste) water based on no back pressure? Am I actually dumping more than 4 gallons down the drain per gallon of good water?
 
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