I successfully replaced the syphon of my toilet, but on reattaching the cistern to the base, the cistern inlet pipe started leaking where it connects to the main water source. It looks like the rubber washer inside the valve is worn away to shreds. It may be quite difficult to tell from this photo, but the red bits inside the valve are just ripped to bits:

mains to cistern pipe with shredded washer

I'd like to know how best to fix this. Of the solutions I can think of, I have questions about it:

  • get a new washer. In this case, I'm worried that a fixed 'lip' on the pipe would make it difficult to fit a washer. Also, how would I describe the kind of washer I'm looking for?
  • replace the valve with a a service valve like this. In which case, will that be compatible with the existing pipe which looks to be fixed in place?
  • replace the fixed pipe with something else entirely. In which case, might be time to call in a real plumber :)

Additional info: this is a UK house, these fittings are probably around 20 years old.

How do I fix a leak in this inlet pipe?

  • Whatever solution you eventually adopt, I would certainly try and sneak a service valve in there, if you can. Pays off the next time you fix something in the toilet and don't need to kill the water to your whole house. Jan 19 '15 at 13:32
  • I may have the terminology wrong, just below the connection pictured there is another valve which allows turning the water off. Although, it's worn down to the point that I need to use an adjustable spanner to turn the water off, as the handle doesn't catch. That could do with replacing :) Jan 19 '15 at 15:48

That looks like standard UK 15mm copper pipe with an olive and compression fitting.

enter image description here

The correct term for the "washer" is an "olive". It is made from copper. If it is damaged, you will have to

  • buy new "15mm compression olives", they often come in a pack of 5.
  • cut off the old olive (you can get olive splitters to do this job)
  • clean up the end of the pipe with wire wool (or similar) until bright and shiny.
  • make sure the end is circular and undistorted for at least 1 cm
  • make sure there is no burr or lip at the very end (use fine grit sandpaper)
  • slide a new olive over the pipe (above the compression nut)
  • ensure the parts to be connected are clean
  • screw everything together

So long as everything is clean, smooth and undistorted, you don't need any plumber's gunk, gloop or PTFE tape.

Don't overtighten, if it weeps you can tighten a 16th of a turn or so.

If necessary, you can cut the pipe further down and fit an extra joint with a short length of new pipe, you might be able to use a flexible connection hose for future convenience - some of these can incorporate an isolation valve. A professional plumber would use an end-feed soldered copper joint but you can get ring-solder joints that just need heating with a blow-torch. Compression joints are easy and compact (and my preference) but you can also use push-fit connectors (HEP2O, Speedfit, etc) so long as they say they are OK for copper as well as plastic pipe.

  • Very detailed, highlighting the correct terminology is very helpful. I should have said in the question, but the copper pipe shown doesn't connect to another copper pipe, instead it attaches to the cistern inlet pipe, which is plastic with a thread on it. Does that make a difference? Thanks again. Jan 20 '15 at 15:09
  • 2
    @Grundlefleck: Yes that does make a difference. In that case you may need to buy a new washer and not an olive. The red washers are usually (but not always) fibre washers (not rubber). I would dig out the old one and take it to a hardware store. Typically they sell packets of that sort of washer in several sizes. Jan 20 '15 at 15:16

Mine was the very same. Re connected with a rubber washer. Leaked slightly now wanting to remove it all again and replace with an isolation pipe,but I now need to cut part if the metal pipe away as isolation pipe is too long.whuch I would need to re thread and the other part would go to the plastic inlet pipe into cistern. But definitely get the fibre washers not rubber.

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