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Discuss identify back nut size please? (bathroom sink waste) in the Bathrooms, Showers and Wetrooms area at

  1. ColdEagle

    ColdEagle New Member

    my basin pedestal sink has been leaking finally managed to edge the stand forward and have identified that the black back nut is split into two. this holds the 'top' of the waste pipework to the bottom of the sink?
    across the middle its roughly 2 3/4 inch and from outside edge of nut (the straight sides bit) its 2 inch.

    I am struggling to locate this anywhere, my local merchants don't stock them nor do the 'sheds' or screwfix, so am looking online (amazon preferred as next day delivery) but cant seem to find any this size, ebay have some but I don't know how they measure if its middle or outside nut edge?
    can anyone direct me please? maybe I'm looking for the wrong thing? or measuring incorrectly? It doesn't look like an old sink?
    Last edited: May 2, 2018
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Best was is to replace the whole waste piece Don't think you will be able to just buy the nut on its own

    If you buy the whole waste you should be able to remove the nut and use it on yours
    • Agree Agree x 4
  3. Dkdc71

    Dkdc71 Member

    A standard waste grating
  4. jtsplumbing

    jtsplumbing Plumber GSR

    Isn't Plastic wonderful Just get a complete new Basin waste ask if they have one with a Brass back nut
    • Agree Agree x 1
  5. S.P.S.

    S.P.S. GSR

    It’s a standard 1 1/4” BSP back nut.

    Most decent local merchants will have one. Some of the bigger chains are useless

    But I agree with above, change the waste.

    Brass Flanged Backnut
  6. Gasinspect

    Gasinspect Member

    And use the screwfix waste fitting kit, which is saves a lot of messing around with ptfe and sealant, even our new plumbers on site get it right first time, bargain for £1.99.
    • Like Like x 1
  7. Stigster

    Stigster Plumber

    A plus 1 for the waste fitting kits. I used to use Plumber's Mait and an Ablex washer until I found these things. Very reliable seal.
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  1. basin waste nut size

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  1. basin waste nut size