Does reverse osmosis water corrode copper plumbing? The answer ..
The answer is YES.
I did a very unscientific study of this. I had installed a typical under the kitchen sink RO filter with a storage tank.
And one day I decided to test the water on a piece of copper.
So I took a small glass jar and put RO water in it. Then I took a brand new copper tubing hold down clamp and dropped it in the water. I covered the jar with plastic wrap to prevent evaporation and then waited.
Nothing much happened the first week or so. I changed out the water with fresh RO now and then. And after a month I began to notice the water had an orange tint to it. Hmmmm.
So I continued to change the water out once a week or so.
After about 3 months of sitting in RO water, the photo results are posted below.
Now, I realize, I did not use an actual piece of copper pipe. But I can make a pretty good guess, that if I did, the results would be similar.
You can see the particulate matter in the water. And you will also see that on the paper towel that I poured the water through. The corrosive effect was enough to reveal the base metal used on the copper clamp.
So anyone thinking about doing a whole house RO unit, better think twice if you have copper plumbing. Even if you have pex tubing or similar, the plumbing fixtures themselves usually have copper tubes on them.