Hole for new tap

[Vicario]

I decided to replace my old monobloc kitchen tap. My plumber removed it and then tried to fit the new (German) one. The hole in the sink top was too small! (31mm diameter out, 34mm needed). He did not have the tools necessary to enlarge the hole so re-fitted the old tap. He said that enlargement could be done by a kitchen fitter or maybe another plumber if I mentioned it when doing the booking, as some do have these tools. I can get another tap of the correct size, of course, but I've already got the new one - how would you proceed? The sink is made of that very hard white plasticky material and he pointed out that if done incorrectly there could be splitting of the unit (which cost about £400). (Why can't the required hole size be standard, as these taps are often replaced?)

 

[Rodders53]

Where did you buy the new tap from? Can you return and get a different one of the correct size (if such a beast exists nowadays, and you can determine the hole size needed from the suppliers/makers data - it's rarely mentioned).

Enlarging a hole in a granite / quartz / other hard material of any thickness is not a simple thing... and may even need access from both sides? A diamond grinding tool of some type to carefully and slowly enlarge (possibly wet / water cooled )... Search for < diamond finger milling bit > or similar.

Wait for advice from some of the professionals who know more than I...

35mm seems the most common hole size (taps being circa 34mm diameter), 28mm used to be used some time back... So your 31 is definitely an odd one out.

 

[Vicario]

Thanks for that advice - it confirms that the plumber was being correctly cautious. We measured the hole together and it's definitely just over 30mm. Your 35mm seems spot on for the new tap - I was tempted to get out my hacksaw while he was here but he advised against!! I got the new tap from B&Q. Can I just add something, which means that I shall certainly have him back for future jobs. He asked why I was replacing the original tap, as it looked very good. I told him that I had had problems with it coming loose and more recently there was quite a bad leak from the spout where it joins the body of the tap... He replaced the original, then he got under the sink... two minutes later he emerged and said that it wouldn't move again for a few years at least! He the removed the spout and went to the van to retrieve his box of O-rings (I've never seen so many in my life). He spent ages choosing several, which he fitted onto the base of the spout. Result; my original tap is as good as new. £95 and a job well done - I hope that the professionals on here read this, because that's the way to get repeat customers. I said that it wasn't his fault that I'd bought the wrong size, but of course I'd pay him the agreed amount... this was before he did everything else and left me with a perfect tap. Not the new one but it's fine. And yes, we're in SE London.