I've got a leaky toilet that I'm trying to fix (and in the process making worse). The leak seems to be coming from the brass nut on the right of the photo here:

Leaky bolt

This nut has a washer in it so hopefully replacing either the nut or the washer will do the trick. Can anyone recommend/help with:

  1. If I should try to replace the whole nut or just the washer inside it
  2. Where I can buy replacements for these in the UK (I don't know what to search for on B&Q...)
  3. If I'm replacing the nut, can anyone guide me on how to remove this from the pipe (it didn't seem to come off easily!)
  4. The white tube currently rotates as I try to tighten (or loosen) the nut. Any recommendations to stop this in order to get a tighter seal?
  • Is that brass bolt in its original position? Is it holding the tube coming from the right in place or was it helping hold the bolt against the toilet body (ie: is it supposed to be more to the left?) Oct 8, 2012 at 18:43

2 Answers 2


There will indeed be some type of rubber, silicone or other type of flexible materal washer thing inside the nut. The cross section picture below attempts to show how the typical compression fitting of this type works.

enter image description here

As the nut tightens it compresses the "rubber" part against the end of the threaded plastic piece and around the outside of the incoming water line. Leaks can arise as from this "rubber" part getting hard and inflexible. The chorine added to water can accelerate this this problem. Over tightening the compression nut will also lead to problems. Sometimes a corrosive build up on the water tube can also lead to leak issues. Usually it is combination of all three elements and everything is OK till there is some flexure in the joint and then it starts to leak.

To fix it is suggested to replace the compression nut and the "rubber" part. If the inlet tubing is corroded then clean it up with steel wool. If the plastic threaded part is stripped from previous over tightening then you will also have to replace the fill valve assembly in the tank too. You should be able to find replacement parts at hardware or home stores. Replacement parts are usually fairly reasonable in cost.

  • many thanks for the reply with diagram! I've had a go at fixing this but had no luck. I've stripped out the old washer from the nut and put a new washer in, but even with @UNECS's teflon tape, I still get the leaks after doing everything back up. I think I probably will need to replace the plastic part (not that I can notice any stripped thread) and perhaps the compression nut too. I'd be able to do the plastic but myself, but the nut is fixed to the metal pipe, so I think this is going to require someone with more skill / a bigger toolkit than me...
    – Jamie G
    Oct 10, 2012 at 7:44
  • @JamieG - The compression nut is probably just slid onto the metal pipe. The whole threaded plastic piece should be able to be easily removed from the side wall of the toilet tank and then you would be able to see the end of the inlet tube. Once this is achieved the compression nut should be removable simply by sliding it off the end of the inlet tube. I am not sure how you replaced the rubber part if you were not able to slide it onto the end of the inlet tube after the compression fitting was in place. Could you respond to that?
    – Michael Karas
    Oct 10, 2012 at 11:15
  • @JamieG - Or is your inlet tube one of those pre-made flexible pipe assemblies with the ends crimped on??? Maybe you can show some more picture details when the compression nut is free from the threaded plastic part. If your inlet is of this type then my picture is probably not representative of your case. Your comments?
    – Michael Karas
    Oct 10, 2012 at 11:18
  • Hi all, I'm very pleased to report that it's fixed - largely thanks to your help! The brass nut did not come off the pipe because there was a solid piece soldered/brased/attached with metal that could not be removed (which stops the bolt falling off the end). I did replace the plastic pipe going into the toilet with stop-cock mechanism (£5.50 from the shop down the road) and replaced the washer again and this did the trick. I think the problem was that end of the old plastic pipe had a sharp bit which was destroying the washer when I tightened. Now all fixed, thanks for all the help!
    – Jamie G
    Oct 10, 2012 at 15:32

When you under the nut is the washer inside,which should either be a crox or nylon olive if it is a crox formed in the copper pipe you can just Pit Teflon tape around it to reseal it, the same if it is a copper olive. If it is a nylon olive just use a sharp knife to cut the olive then slide it off and replace it don't put the olive in the same spot on the pipe though or it won't seal properly. As for holding the threaded plastic just a firm grip with adjustable pliers is fine . It looks like the nut has been over tightened tho which may have striped the plastic thread...

  • I agree with @UNECS, just try some teflon tape first. It may be called plumber tape depending on where you are
    – GdD
    Oct 9, 2012 at 7:25

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