why isnt RO water good enough

[SeanK]

i have a 4 stage spectrapure RO/DI unit and i hate that the "waste water" which goes through two .5micron filters and a reverse osmosis unit gets drained.

cant i just put the product and the "waste" water in the tank?

 

my RO water is 3ppm and RODI is 0ppm. is 3ppm really going to make a difference?

its such a waste of water. 20 gallons for every 5 gallons i put into my tank.

[krug1313]

If your going to put the waste water in too you might as well use tap water. 3ppm from your ro is fine to use 0 is best but it won't hurt anything. Run your waste line in a 5 gallon jug and water your garden or throw it in your washer when doing laundry. Then there is no waste if your worried about it.

[Zepo.]

You do understand how a RO system works right? The waste water + the ro water = the original water...You can always collect the waste water and use it for something else.

[krug1313]

Test your tap water and you'll see that 3 ppm is a huge difference. If you were to use the waste water in your tank your defeating the purpose of an ro machine.

[SeanK]

You do understand how a RO system works right? The waste water + the ro water = the original water...You can always collect the waste water and use it for something else.

 

but the waste water goes through the .5 micron filter and .5 micron carbon filter and the RO membrane. doesnt that make a huge difference as opposed to water right from the tap?

[krug1313]

but the waste water goes through the .5 micron filter and .5 micron carbon filter and the RO membrane. doesnt that make a huge difference as opposed to water right from the tap?

 

Yes. The ro machine directs the waste water and clean water seperate directions. You don't want the waste water in your tank only the cleaner water from the ro. If you were to mix the waste water and ro water then that would pretty much give you tap water minus some of the particles the filters took out. Does this make sense? I suggest using a different color tube coming from the output for your good ro water. This way you don't get them confused.

[SeanK]

Yes. The ro machine directs the waste water and clean water seperate directions. You don't want the waste water in your tank only the cleaner water from the ro. If you were to mix the waste water and ro water then that would pretty much give you tap water minus some of the particles the filters took out. Does this make sense? I suggest using a different color tube coming from the output for your good ro water. This way you don't get them confused.

 

i dont mix the tubes, i only put the product water in my tank.

i was just wondering why i had to waste all the waste water.

 

what does the DI unit actually take out that makes it completely different from RO tap water?

[krug1313]

i dont mix the tubes, i only put the product water in my tank.

i was just wondering why i had to waste all the waste water.

 

what does the DI unit actually take out that makes it completely different from RO tap water?

 

The di is the last stage that will take you to 0ppm. You can use ro if yours is 3ppm it's not going to hurt anything. Your setup is fine. We all hate wasteing the water but unfortunatly that's how an ro or rodi machine works. As I stated above you can use the waste water for laundry, gardening etc. Just run the waste tube into a bucket or jug.

[alex1237]

I think the confusion is that the waste water and the product water coming from the ro are different. If your RO is reducing the water to 3ppm the waste water is not also 3ppm it is significantly less desirable (likely worse than the original tap). So the difference between the waste and product water is more than just the di stage.

[Raimond]

I ran a line through the wall under the sink (to the back yard) and use the waste water to keep the trees green.

 

I like the washing machine idea...

[cruiZe]

all the water goes through the first filters (which remove UN-desolved solids)

 

say your tap is 500tds, 1 part of that makes it through the r/o membrane to become 3tds, the other 3 parts don't make it through. The tds from the good water stays behind, meaning that the waste would be around 665 tds (500tds x 4 parts - 3tds of product x 3 parts remaining) it could be a bit lower because of the pre-filters, but the waste water will always be as bad or worse than your tap.

 

You could set something up to run the waste water through again, but whatever.

 

to clarify, waste water does NOT make it through the membrane.

 

3 tds is nice, but nitrates and phosphates are very small molecules and the 3 tds might be the worst ones.. just keep using the DI stage, if you're getting that good of ro, the di should last a while.

 

ro runs to my fridge, its fun giving a glass to guests and asking them what it tastes like, then seeing their face b/c they have never tasted 'nothing' before

[AZDesertRat]

The waste TDS is 20 to 25% higher TDS than the tap water, it has not been through the membrane, it only flows around it carrying away the concentrated waste. This is true of all RO systems.

[MEDGE]

your waste water isnt making it through the RO membrane only the first two stages.

[Dani3d]

that's a really really wierd question. the waste is what you don,t want that the unit as taken out so why the heck would you want to put that in your tank???? big big question mark here..

 

if you hate the water waste, sell that unit and by the zero waste type of unit. They exist, they cost a little more but there is no waste.

 

3ppm is not goint to make a big difference no. My RO/DI is now producing 2ppm and I am not going to change the membrane until it reach at least 5ppm.

 

yes it's such a waste of water, get the zero waste unit.

 

here you go:

 

http://www.costco.com/Browse/Product.aspx?...topnav=&s=1

 

 

 

i have a 4 stage spectrapure RO/DI unit and i hate that the "waste water" which goes through two .5micron filters and a reverse osmosis unit gets drained.

cant i just put the product and the "waste" water in the tank?

 

my RO water is 3ppm and RODI is 0ppm. is 3ppm really going to make a difference?

its such a waste of water. 20 gallons for every 5 gallons i put into my tank.

[AZDesertRat]

You replace the DI resin when the TDS goes up, not necessarily the RO membrane unless it shows it is not performing at 96-98% rejection using your TDS meter.

 

The Watts Premier zero waste unit is not really zero waste at all. What it does is use a booster pump to inject the waste back into your hot water heater. This is counterproductive since many of use use a water softener to filter the water, whey would we ant to concentrate what is left and dump it into our homes plumbing?

 

You can buy Ultra Low waste RO/DI systems but as you mention they are not inexpensive since they are microprocerssor controlled. The one I use is the MaxCap UHE from Spectrapure and it is the only long term proven system on the market that truly works as advertised. Others have attempted low waste but they have inherent problems since they use high TDS tap water to flush the membrane unlike the UHE which uses DI water.

[cruiZe]

wouldn't zero waste be impossible? I mean the bad particles have to go SOMEWHERE, they can't just vaporize. I guess using the waste water for another purpose isn't really wasting it, but they lead you to believe that its all going through by saying its 100% efficient.

[AZDesertRat]

Exactly, its not possible. The Watts still wastes 4:1 it just dumps the waste into the hot water heater. Thye have other limitation and problems too such as a practical limit of 35 to 50 GPD since there is not sufficient room in the hot water system with out expansion valves or blowoffs.

[Zepo.]

Just food for thought. I had 6-7 PPM before i changed my filter and had crazy cyano problems, it was like a carpet covering everything. I changed the filters and replaced the resin with color changing kind and all cyano is gone and macros are dying off because of the low nitrates and phosphates. Even at 3 there will be a difference going to 0.

[AZDesertRat]

To be clear, prefilters and carbons have very little to absolutely nothing to do with final TDS, they are there to protect the membrane from chlorine and TSS or suspended solids, big stuff like sediment and particulates not TDS or microscopic dissolved solids.

The RO membrane and the DI resin remove the TDS. I wouldn't depend on most color changing resins for much, they normally turn colors too late or in streaks so you have no idea the condition, always rely on the TDS meter not a color change. By the time the color changes you are releasing weakly ionized contaminants.

[amnestia]

3ppm is fine, read it out three-parts-per-million. That's VERY little, all salt mixes you can buy at a LFS will have more heavy metals/waste in it than that.

 

Enjoy

[AZDesertRat]

3 PPM is not fine unless you know exactly what that 3 PPM is comprised of. With TDS you are measuring everything electrically conductive so you have no idea what it is made up of so to be safe you change the DI resin.

[wyattroa]

I am still learning about the who water thing.. Do any people ever wonder how people were able to get by with their tanks before all this came out. Almost like all the crazy baby stuff that is out now.

 

If i read the original post correctly if I were to buy a unit and want to fill by 24 gallon tank i would actually go through roughly 110 gallons... wow.. thats a ton of water.. How long does it take some of you to fill these big tanks?

[AZDesertRat]

Its actually about 120 gallons but you flush more than that down the toilet every day and don't think a thing about it. The brine or waste can be used for other purposes like landscape watering or laundy too, it does not have to go down the drain.

 

The average RO/DI is a 75 GPD meaning it will make 75 gallons of treated water in a full 24 hour period with an incoming water pressure of 5-060 psi and a water temperature around 77 degrees F. Higher temperatures and/or pressure make water faster while lower temps and pressures slow the unit down. Colder water does treat better though, the membrane works better and DI resin lasts longer so it has its advantages.