I had to remove the compression valve for the toilet during my bathroom floor install. When I started out I did not know how compression valves worked and ended up putting a lot of power into tightening the nut when I was intending to loosen it :-P Once I finally got the valve off the correct way, I found that my misguided efforts had resulted in a noticeable impression/dent in the copper pipe where the collar (ferrule?) of the valve had sat. The dent is small, I'd say about on the level of the creases at the joints on your fingers when you hold them straight (I didn't get a picture with the valve off, but including one before I finally got the collar off to give a sense of how I kind of banged it up).

I decided to have a go at simply re-installing a new valve to see if it would work - that was 3 weeks ago and there is just a verrrrrry small amount of moisture below the valve now to suggest that there is just a verrrrry small leak.

Now I'm trying to decide if:

  1. I should remove the valve I installed and cut the pipe so that I have a PERFECTLY smooth surface for the new valve to seal against the pipe. I've got a pipe cutting tool but am somewhat concerned that I won't have much pipe left protruding once its cut. I can pull the pipe up a bit with very little force so this doesn't seem like a HUGE issue.

  2. If I do cut the pipe, do I need to cut it all the way down to where that dent is, about an inch, or just enough so that the spot where the collar of the new valve will go will be clean pipe? that i think would require cutting at most 1/2 of the pipe

  3. Can I re-use this "new" collar that I installed 3 weeks ago over the somewhat dented pipe, or should I start afresh with a new one? I guess I might as well just go new since they're not expensive and that's just a bit of extra insurance for a successful seal.

Any advice is much appreciated, thanks!!

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  • 1
    When you cut the old ferrule off, will you have at least 1 1/4" to 1 1/2" of pipe extending from the wall? This is after you cut it directly behind the ferrule, removing the old nut and escutcheon. More the better. But the answer to your question is sorta, yes it has to be smooth were the ferrule goes, there is a little forgiveness using a compression fitting, a fresh one.
    – Jack
    May 22, 2021 at 15:19
  • @Jack when if I cut the pipe where the old ferrule rested (so that it's all clean pipe), I'd have at least 1.5" extending from the floor as it naturally sits, 2" if I lift it a bit. Another reason I hesitate to cut is that a bit of water still occasionally comes out of the pipe even with the main valve shut off (and all other fixtures open), so it'll be stressful to deal with that while cutting the pipe!
    – aknodt
    May 22, 2021 at 16:21

1 Answer 1


I have done four things with this second-hand olive issue:

  1. wrap with 4 or 5 layers of ptfe then tighten normally. Usually is fine.

  2. use a sealer such as plumbers mate or equivalent and that has also worked.

  3. replace the olive but as you have compressed the pipe so much you may have to cut the pipe back. To do that you may have to get more pipe and pulling it may not be sufficient so you will have to get behind.

  4. use a solder joint to put a fresh bit of pipe and push it back into the cavity but does depend on the cavity...

  • Thanks @SolarMike! Re #2 using the sealer - do you mean that's something I could just add to the pipe around the valve I've already installed (that would be amazing), or something that I would need to put around the ferrule during a fresh installation (i'm guessing this is more likely).
    – aknodt
    May 22, 2021 at 16:48
  • 1
    You put it around the olive before assembly so it fills the spaces.
    – Solar Mike
    May 22, 2021 at 16:52

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