ro/di ?

[danfish]

i just bought my 1st ro/di unit,(never had one b4) after installing it and started to run it, i notice the drain tube was flowing about 10x(fast stream) more than the pure water tube.(fast drip) is this normal ? if it is that means
that i`ll be wasting 10 gal of water to make 1gal of pure water .

thx

 

[Tonyscoots84]

it should be 4 gallons of waste for every 1 gallon of pure water.... dont quote me on it... if that is actually happening there might be something wrong with the setup... take a pic and show us..

 

[TimberTDI]

A little more info, type of unit, used, new. etc.

Steven

 

[loismustdie]

Go to HD and get one of those johnny guest ballvalves and attach it to the waste line. Restricting the flow on the waste line will get you more pure water compared to waste... something along the lines of 4:1 as Tony has said. When that waste line is wide open, water will travel the path of least resistance. RO membranes need back pressure on them to perform best. During the colder months, you will also get a worse ration due to cold water. Best results with RODI occur when the water is 77 degrees, 40 PSI with some restriction on the waste line.
As we all know too well, there is a lot of waste when it comes to running RO. It's one of those things we try to prevent, but there is only so much we can do. Personally, I took my RO chamber off line and just run the sediment and carbon filters then through 3 DI chambers. I go through DI resin twice as fast because of this, so even though I use 100% of my water, replacing DI resin isn't exactly cost effective. My TDS from the tap goes between 28 and 32, and that is the only reason I would even try DI only. I can't give long term pros and cons since it has only been running a few months and I'm not saying you should try it.

 

[fishguttz]

ro/di wastes a lot of water!

 

[danfish]

i did a test on the ratio and i was alittle off, is more like 6:1.
another question is what loismustdie said, for best results water should be 77 degree, and my tap water is no where near 77 degree, does that mean i should run warm water instead of just cold?

 

[loismustdie]

and my tap water is no where near 77 degree, does that mean i should run warm water instead of just cold?

If you make a mistake and the water gets too warm, you'll kill your RO membrane. As for cost effectiveness, it's probably not worth feeding warm water for a possible gallon. There is an in line heating unit you can get, but I don't think that's worth it either.
Have you restricted the waste line at all? You'll probably get more out of that than you will out of warming your water.

 

[danfish]

thx for ur advice loismustdie greatly appreciate, i will get the valve 2day and try it. one more thing do u know were i can get a tds meter in the manhattan, i want to test the h2o and see how the quality is, dont want to wait for mail order if i dont have too. again thx

 

[Buckeye Field Supply]

A few claifications - Filmtec membranes are rated at 77 degrees and 50 (rather than 40)psi.

You'll want a needle valve (otherwise known as an adjustable flow restrictor) for your waste line rather than a ball valve. Be careful that you don't go lower than a 3:1 ratio of waste to permeate.

Russ @ BFS