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Discussion Starter · #1 ·
Does it make any difference if you use cold or warm water when running your RO/DI filter? And am I the only one who stood there and watched the thing for a solid hour making water (first RO/DI system)?
 

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Mines Ice cold coming out of the ground. They say that it does a number on the RO membrane but I have have never had a problem. Are you to cold or to warm. If you are to cold you can do what I did. I took a 5 gallon pail put a 300W heater in it. heated it to 72 and put all the extra line I purchased coiled up in the bucket. Them by the time it gets to the membrane after all those coils it should be warmed up. I tried this and it worked for a little while but then stopped. I think my water was cold + traveled through the hose fast which caused the water in the pail to cool faster. The heater couldn't keep up. Maybe if I would have used something that was insulated it would have worked.
 

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Discussion Starter · #3 ·
I've got city water here, but as you said I too have heard that too cold could affect the membrane. I've been trying to run the faucet at 78, figure it will cool to around 76 by the time I get it to the tank. I don't have a TDS meter yet, and didn't want to trash the membrane on a new filter. Thanks..
 

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My understanding is that cold water will not hurt the membrane, but will reduce output and maybe even affect the efficiency of the membrane (allow more to pass through than with warm water) RO membranes are rated at 70-80 psi entering water pressure and an entering water temperature of 77. Altering either the pressure or the temp is going to have a negative effect on output. It shouldn't have a negative effect on the life of the membrane though, as far as I understand it.

I think I read someplace that too warm of water will have an affect on the life of the membrane however, so don't run hot water through it.
 

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There's some "not-quite-right" info in this thread - let me get some different info in here.

RO membranes are tested by the manufacturer under a standard set of conditions. Filmtec for instance tests their membranes with 77 degree water at 50 psi. There are other standard conditions but let's focus on temperature and pressure for now.

Other manufacturers use different standard conditions - 77 degrees and 60 psi (10 psi higher than Filmtec) is the most common.

Nothing says these conditions are optimal - they are just the test conditions.

If you provide different conditions (most people do), then your membrane performance will be different than what the manufacturer specifies. We have a calculator on our homepage where you can plug in your pressure and your temperature and see how much water your membrane should produce based on those conditions.

With colder water, you'll get slower production, higher rejection, and more waste water.
Water colder than 77 degrees won't damage the membrane.
HOT water will damage the membrane. Anything over 113 degrees F voids the warraty on a Filmtec membrane.

Russ
 
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