Are basin tap holes supposed to be this wide?

10 Jan 2013
Reaction score
United Kingdom
I have a basin here with tap holes that measure over 30mm in diameter. The tails on my taps are "15mm" or whatever, so about 20mm OD in practice. So there's loads of lateral play no matter how they're tightened up.

Also, the washers I've got have an OD only just larger than the holes in the basin! So they're hard to get sat centrally and tend to collapse into the hole when the tap is tightened down.

I dug the old basin out from the pile of rubble on my drive and it turns out the holes on that are the same. And, the washers on the old taps are the same as the washers on my new ones. I didn't pay much attention when removing them, weeks ago now, so can't remember how secure they were.

But anyway, the upshot is that when tightened down (tap-rubber washer-basin-rubber washer-plastic back nut) the tape rotates very freely indeed.

What's the best solution? Wider washers? Fill everything with silicone?

If I silicone it should I remove the top washer altogether so the flat base of the tap body contacts the basin surface?

EDIT: "fix-a-tap", some bits and pieces to correct this issue. Recommended?
Sponsored Links
You can buy washers that centre the taps from underneath specifically made for the job from any good Plumbers merchants
You can buy washers that centre the taps from underneath specifically made for the job from any good Plumbers merchants
I was trying to find these so I could post a link, cant find them, I have seen them.
Links in this post may contain affiliate links for which DIYnot may be compensated.
Sponsored Links
"Top Hat" Tap washers, Plumbers do not seem to use them very much these days.

Get rid of the rubber from between the basin and backnut.

Then you will be able to tighten it properly and it won't move.

The top hat washer are a good idea but I very rarely use them
A big thank you to Slapper for taking the time to help?

Wickes didn't stock either the centralising washer or brass back nuts :)roll:) but Toolstation (my first visit since 2009, how time flies) provided me with both. Together they seem to do the trick!


All looks good and the taps are now secure, but I haven't put water through it yet. I'm waiting for the bucket load of silicone to cure in my slotted waste :/
Ref Top hat washers.

This 'Registered Plumber' uses them on Basin, Bath and Kit Sink (pillar type, not mono bloc) taps, saves a whole load of aggro, keeps the brass back nuts (use them as well, placcy ones are carp) under compression, so always held tight on the threads.

I did not know the top hats had been phased out!

In fact I thought they were virtually essential when fitting taps.

Top hat`s original purpose was for s/steel sink tops - when the pillar taps threads (tho` longer than now) didn`t go up far enough to use a thin plastic ( or lead) washer under the sink . A strip of wood with 2 holes made wi` brace and bit was much better anyway ;) And basins had square holes .

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links