This pipe comes out of the floor of my kitchen and I am wondering if it is gas or water.

It isn't close to the other water lines by the sink and there is a gas stove on the opposite side already. I am hoping it is a water line as I want to install a freezer in this spot where the previous owners had theirs.

The pipe seems to have green corrosion and I can't tell if the pipe has always been black or just corroded.

How would I find out for sure?


  • Can you trace the pipe from below or on the other side of the wall, etc? Are there other pipes nearby? Are there drain pipes nearby? I'm thinking copper isn't usually used for gas lines, but it seems odd to see a single water pipe and not a partner for hot and cold supply. It could be leftover from forced water heating, a drain pipe, or something else entirely.
    – gnicko
    Sep 13, 2021 at 18:51
  • @GregNickoloff There are no other pipes on that entire wall, I can't trace it because it just goes straight down with no access underneath. I'm only assuming the pipe is copper because as far as I know you don't often see green corrosion on steel but I may be wrong.
    – James
    Sep 13, 2021 at 19:46
  • What part of the world is this? That is an unusual cap... Sep 13, 2021 at 23:16
  • Did the house formerly have radiant heating? Sep 14, 2021 at 0:32

1 Answer 1


Based on the color of the pipe (green corrosion) and the fitting being use to cap the pipe off, I'm going to say it's a water pipe. Gas is normally run in steel threaded pipe, and it might be done in different areas, but I've never seen a gas line run through the foundation. It normally runs through the walls/attic.

  • For what it's worth, I almost blew myself up by drilling into a gas line that was barely buried in a slab on grade house. Sep 14, 2021 at 0:26
  • Ouch. I agree that if in doubt it's better to err on the side of safety... One could bring in a gasfitter to open it up and find out, but that's emphatically a job for a pro.
    – keshlam
    Feb 5, 2023 at 20:25

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