Leaking where rigid copper pipe is coupled to the cistern. I tried wrapping
ptfe tape over the brass collar but still leaked. Had a second go and was able to tease the copper pipe out a bit and a perished fibre (?) O ring washer came out the threaded coupling - will replacing it alone do the trick - and what do I order? The ring material is approx 3mm width and
3mm depth.
Most likely you will need to replace olive on your pipe work. Also determine which part is leaking from and replace washers as they most likely too old. Then make sure all part are tight enough but don’t over tighten as they can break
1/2-inch fibre tap washer, be careful not to cross thread the fitting when retightening
1. Stop (close) water on insulator valve if fitted next to cistern. If not fitted close main stop cock in the property.
2. Open cold tap to release pressure from pipes. This way splash of water can be avoided.
3. Undo (unscrew) normally female 1/2 connector on copper pipe.
4. Remove the O ring (may be black or red) and buy appropriate O ring. Standard size 1/2.
5. Screw back copper Female 1/2 to cistern.
6. Oent stop cock to check
Good luck