I'm planning to connect my ice maker to my reverse osmosis filter, which will likely involve drilling a PEX line into the basement & running over to the fridge, back up through the floor.

As a result the existing copper line to the fridge will become a dead leg, six feet long or more.

I believe I need to fix this, but I keep wondering if there's a good reversible fix. I would hate to just chop it all out permanently. Could I splice in a ball valve? Or would the small dead leg to the ball valve still be too big?

If there is no reversible fix, is a cut-and-cap advisable? A plug? Or should I go all the way and try to desolder the branch out of the T-junction?

Lastly, since this is cold water, just confirming legionella is still a concern? Our groundwater gets darn cold in the winter (Zone 5), but in the summer ambient temperature is within legionella growth range.

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    What size copper pipe goes to the fridge? If it's rigid copper, could you just connect to that from the PEX instead of drilling new holes in the floor?
    – aghast
    Commented Jan 12, 2021 at 0:26

1 Answer 1


I would advise to shorten it as much as possible, no sense in having unused pressurized lines. Do a professional job of soldering it closed or put a quality valve and cap on the line, reducing the possibility of leaks.

  • Will the water from the RO system give you the taste you want in the ice cubes?
    – Paul Logan
    Commented Dec 13, 2017 at 6:54
  • I guess I hadn't been worried about taste, maybe something to read about. It's connected at a tee right now, maybe I can successfully remove the tee and replace it with the appropriate junction. That would be the cleanest with no dead leg.
    – user76412
    Commented Dec 15, 2017 at 18:48

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