I am doing some remodelling and I want to find out if a pipe is in use or if I can remove it. Behind the wall where the Red arrow is, there is a pipe running all the way to the ceiling. I would like to remove this. Green arrow - wire which doesn't seem to have any voltage in it. Purple - pipe I want to remove. Yellow - more pipe to remove.

The property is fairly old and I have found many things that weren't needed but left there. All these pipes are near a gas fireplace which doesn't work/turn on.

Just wanted to know if there are any signs that would point that this is either water/gas before I call a specialist. Is there any way to check if these are still in use?

Any advice/insight is appreciated. Thanks! enter image description here

  • Off hand my guess will be towards those pipes being used for gas. The green wire is for grounding the pipe, sparks not good near gas. Should be shut off valves somewhere near there, in basement or on outside wall.
    – crip659
    Feb 13, 2023 at 15:21
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    The only way to know is to trace the pipes through the walls. Unfortunately, neither copper nor brass are magnetic enough to be able to reliably trace them with a magnet, so you may be looking at opening up walls to see where they go. If you're not comfortable with this, you may just have to go straight to "hire a pro". The same holds true for the wiring. You say it doesn't have any voltage - how did you measure? It appears you're in the UK, are you sure you're not testing something with a blown fuse or switch turned off?
    – FreeMan
    Feb 13, 2023 at 15:22
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    Do you have active gas service? Are there any gas appliances in the house that do work? Do you pay a gas bill? As for plumbing pipes, beware of deleting vent pipes that you might misclassify as "not in use" due to no water in them.
    – Ecnerwal
    Feb 13, 2023 at 15:48
  • Stab a hole in it and see if you get wet ;) (obviously, I'm joking) Feb 14, 2023 at 14:15
  • Thanks all for the advice. I am in the UK indeed. I have used a voltage indicator to see if the wire is in use.
    – Catalina
    Feb 14, 2023 at 18:40

4 Answers 4


The wire below the green arrow is green/yellow, which indicates a ground wire. It is connected to the copper pipe below the purple wire. It is normal, and in many places required to ground the electrical system to copper water piping. However, it is not a good idea to ground to gas piping. You need to find the other end of the green/yellow wire to see if it is a current (pun intended) ground wire or not. Check your breaker/fuse panel(s), as it should end there.

  • Any metallic piping system is required to be grounded, gas included. This would ordinarily be achieved by connecting pipe to grounded equipment, but separate bonding conductors are acceptable and widely used.
    – kreemoweet
    Feb 14, 2023 at 0:31
  • @kreemoweet This may be somewhat jurisdiction dependent. In my area (and as I understand it generally in the US), the grounding wire from the main panel goes to ground rod(s) and (not always, depends on jurisdiction) to the copper water pipe. Feb 14, 2023 at 0:49
  • @kreemoweet isn't that the opposite? Grounding the pipe vs grounding equipment using the pipe as ground? I would happily ground my gas pipe, but not use it as ground. (If it hadn't had a PVC cover that is.) Feb 14, 2023 at 7:49

In the UK, gas joints are anti-threaded - turn clockwise to loosen. You can run your fingernail along the exposed thread to see which way it runs.

  • That's actually rather clever! Keeps those meddlin' kids from unscrewing gas lines.
    – FreeMan
    Feb 14, 2023 at 13:06
  • In Australia and South Africa do they flip around the gas vs. water threading? Feb 14, 2023 at 15:10
  • This is a great shout. Will give it a go as I am based in the UK
    – Catalina
    Feb 14, 2023 at 18:43

Easy way to detect a water pipe that is in use, is to run water from all your taps for a while. The pipe will get cold as cool water runs through it (and of course it will work for hot water also).

If you have another person to help you, you can ask them to lightly tap the pipe with some metal tool, and listen for the sound with your ear against the pipes in other rooms.


Traditionally galvanized steel ( grey/silver color) is used for water and bare ( black ) steel is used for gas. No guarantee. Gas lines usually use cock / plug /ball valves ( 90 degree turn for on- off).

  • 4
    Though quarter turn valves seem to be becoming more common for water, which if you aren't trying for fine gradations of flow I consider a Good Thing .
    – keshlam
    Feb 13, 2023 at 17:25
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    Are you sure that’s the trend in the UK? Feb 13, 2023 at 20:35
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    My 1958 house in North-West England had lead gas pipes. My parent's 1959 house in South-West England had copper gas pipes. Both had copper water pipes. Material is not a sure guide.
    – grahamj42
    Feb 14, 2023 at 0:08

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