Can I do this? I have 3/4 copper, then transition to 1/4 adapter to plastic tubing. Then into the reverse osmosis system. Then, go back to copper plumbing (existing) for white refridgerator box.
IT shouldn't but many new homes here do have a copper line from the sink to the icemaker to supply RO water to it, and have not had problems. At least so far and a lot of them are many, many years old.
HJ, those people running RO water through copper tubing should seriously have a copper test done on their water. Copper and the human body do not get along well at all; the body suffers.