Help with spanner for sink waste brass nut

The waste on the sink has started leaking underneath.  I wanted to try and tighten it up or, if that doesn’t work, take it all off, clean everything up and start again.  The problem is I don’t have a spanner big enough to fit the brass nut.  The adjustable wrench that opens wide enough is too long to manoeuvre in the restricted space and keeps slipping off the narrow nut.  The sink is ceramic so one slip could result in a breakage.  What I need is a hexagonal spanner which is about 87-88mm AF.  An immersion heater spanner would be ideal if only it was hexagonal and not octagonal.  I had thought about ‘modifying’ an immersion heater spanner, but the correct tool must be available.  Can anyone help or suggest alternatives?

I think it is a case of contacting plumbers merchants and it will be the last one you phone or check ebay.

You’d think.  I have tried a few and they confidently disappear around the back and return with an octagonal immersion heater spanner.  I’ll keep searching.


Something like this…±+&utm_source=google&utm_medium=shopping-pla&utm_keyword=ZT1005465X&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=wtqitmmxwm&istBid=tztx&gclid=Cj0KCQiA-JXiBRCpARIsAGqF8wUCQJR5pqI9LXed5YHzdH2ATUnRGbMzE3e541NkN7e8_As_RgoTnE4aAsp1EALw_wcB

Or a chain wrench that they use on oil filters.

I’ve done a few wastes in my time, it’s best to remove clean up and reinstall. I would add if it doesn’t seal by doing that then apply some silicone to the surfaces above and below and inbetween the rubber sealing rings.

Just to add, it looks like it’s been sealed previously with putty or the like and gone hard. No need on a joint like that, as said if needs be silicone seal.



You beat me to it.



This might fit


What about this.

IIRC- I bought mine from B&Q, just ask for sink waste spanner, Any builder’s merchant or Plumbing supply should stock one also. Main point is, how long has the sink been installed, before metric change of after it? We moved into this house over 40 years ago, so the changeover must have been many years ago!

Screwfix do them

Access is so tight its usually easier to remove the sink and re washer and reseal the waste fitting. Rarely tightening the nut will cure it as its usually set in Plumbers Mate and it dries out, this is how they are fitted, avoid silicon if you can. Rubber seal under chrome bit in sink then a big roll of Plumbers Mate beds it down underneath. 


Have you thought about trying Machine Mart
you can check on line.

Maybe something like a big tap-tightening tool would help?  These have the jaws set at 90 degrees to the spanner shaft, so that you can get at nuts which are in confined spaces underneath sinks & baths.

& an expensive one…  

Before you do anything drastic, have you tried Fernox “LS-X” sealant, it’s cured similar leaks for me.  Also, on a downward note, that brass retaining nut probably screws onto the threaded neck of the drainer unit in the sink, and if that is also made from brass there is a good chance that corrosion has fused them together, and no amount of leverage will free them.  There is a good chance that you could end up breaking the lugs off the nut or rotating the whole unit in the sink’s exit hole, or both.  Be careful, be very careful.

Thank you to everyone who has responded so far.  I’m quite overwhelmed by the number of replies.  Plenty for me to start working with.  Please keep the ideas coming and I will let you know how I get on.

I made enquiries and was advised because that is a shallow,  chamfered, circular nut with lugs a “C hook” spanner or plumber’s grips, both already recommended, are your best bet, but with the cautions I previously mentioned.  A sharp “tap” with a mallet on the spanner was also suggested.  Good luck!

Thank you Countryboy.  Your input is very much appreciated.


I was looking on Amazon and eBay at C-Hook spanners as suggested by a couple of posters and noticed that they often appeared in the context of motorbikes. My friend across the road has a motorbike and when I asked sure enough, he had a couple which he loaned me. I was still struggling with access as sods law meant the angle I wanted to use the spanner was blocked by other pipes or the false drawer fronts. In the end I removed everything, which helped access considerably and meant I was able to get the nut undone. It took a while to clean the silicone sealer off everything but instead of putting the solid brass waste back on I used a more modern one that secures from the top. Not as nice but the brass nut was damaged (I suspect the person who installed it struggled to tighten it) and I couldn’t face all this palaver again at some time in the future. I used Plumbers Mait to bed the new waste and fingers crossed we are now leak free.

Thanks to everyone for their help and suggestions. I’m not sure it would have gone so well without your help.

You have exactly the right thing, as a now retired gas and heating engineer i have done a few over the years and unless the basin is built into a unit with easy access you will always struggle afterwards. Even from new it’s one of those joints you sweat on so if basin is off the wall i fill with water to test before refitting because as you found it’s a pitta for access once plumbed up.

I’ve just noted your location.  Maybe next time I will invite you round and offer to polish your MX5 whilst you sort the plumbing.