Plastic pipe leak at compression joint on isolating vavle

[Gooman]

I have a slow leak (about one drop every 20s) from a plastic pipe that connects to a screwdriver isolating valve that feeds our outside tap. It was fitted by a professional plumber around 6 months ago and has only just started leaking. 

 

I've read up and discovered that a common mistake is to not put a liner inside the plastic pipe at the joint. Is this likely to be the problem?

 

There's no extra play in the plastic pipe, so if I cut it shorter I'll have to add something else. What's the best solution here? A short section of copper pipe with a push-fit joiner to the plastic pipe?

 

I'm a novice at plumbing ... changed a few taps but that's about it. Not keen to call a plumber out for just a slow leak if I can avoid it!

 

Thanks

[joe90]

Might be worth tightening the nut a little, hold the body tight with pliers before you do, just a “nip” might be enough, if not, water off, remove nut and use a paste/sealer on the olive and retighten.

[jamieled]

37 minutes ago, Gooman said:

 

I've read up and discovered that a common mistake is to not put a liner inside the plastic pipe at the joint. Is this likely to be the problem?

 

They certainly can leak a bit with no liner. The liner stops the pipe from being compressed in the joint so if you can take it apart and slide a liner in that might work.

[Temp]

Is it possible water in the pipe froze increasing the pressure?  When you turn off the valve to isolate the tap in winter perhaps open the outside tap.

[Kilt]

1 hour ago, joe90 said:

Might be worth tightening the nut a little, hold the body tight with pliers before you do, just a “nip” might be enough, if not, water off, remove nut and use a paste/sealer on the olive and retighten.

+1 for This. If does t fix, you need to take it off and check there’s a liner in there. 
 

you can use PTFE on the olive as well. 

[Gooman]

1 hour ago, Temp said:

Is it possible water in the pipe froze increasing the pressure?  When you turn off the valve to isolate the tap in winter perhaps open the outside tap.

 

Good suggestion, but I knew enough to do that ... and the leak is on the mains side of the valve, not the tap side.

 

I've - carefully - tightened the nut, and it seems to be much improved. Thanks for the tips!

[Timedout]

If there isn’t a liner it will leak. Even with a liner the typical 15mm and 22mm plastic plumbing is prone to leak if used compression joints. We learned the hard way in this with a plumber on a large barn conversion a long time back. He left us with a legacy of leaking compression joints on the Hepworth plastic pipe. I don’t know why he used so many but he assured us it was ok. It was not! We continued to use plastic on other projects but never used it in compression fittings again except for stem fittings which are ok. It’s more reliable to put in a connector and shove in a short piece of copper to bridge to the compression or use a push fit if that is available. Push fit isolators exist.

 

. 

[Nickfromwales]

32 minutes ago, Timedout said:

If there isn’t a liner it will leak. Even with a liner the typical 15mm and 22mm plastic plumbing is prone to leak if used compression joints. We learned the hard way in this with a plumber on a large barn conversion a long time back. He left us with a legacy of leaking compression joints on the Hepworth plastic pipe. I don’t know why he used so many but he assured us it was ok. It was not! We continued to use plastic on other projects but never used it in compression fittings again except for stem fittings which are ok. It’s more reliable to put in a connector and shove in a short piece of copper to bridge to the compression or use a push fit if that is available. Push fit isolators exist.

 

. 

+1. I've been saying this to people for years. Still get stubborn assholes who say "it's OK".......it's not. Copper into compression and a hep fitting onto the copper each and every time = bombproof.