Struggling to find an sink trap adapter.. Any ideas?

[FuerteStu]

Got an 1.5" basin sink waste into 1.75" trap. 

Was thinking such a simple adapter would be easy to find, but alas I'm only finding the wrong sizes, or reverse threads (female to male instead of male to female etc) 

 

I've already got 1.75"pipe and AAV coming up under the sink.. Would it just be better to get another trap and reduce it there? Or can anyone find something like the macalpine T16 that's actually the right size?

[Marvin]

Possibly:

 

https://getplumb.co.uk/products/mcalpine-1-50-x-1-75-bsp-coupling?

 

 

 

[FuerteStu]

Very possible! 

 

Just concerned about the amount of thread on the 1.75" side.. 

[Marvin]

7 minutes ago, FuerteStu said:

Very possible! 

 

Just concerned about the amount of thread on the 1.75" side.. 

Silicone it in using Dow 785 white - (allow 24 hours to dry whilst not fitted to sink and in the dry and warm)

[FuerteStu]

On 27/12/2025 at 12:25, Marvin said:

Possibly:

 

https://getplumb.co.uk/products/mcalpine-1-50-x-1-75-bsp-coupling?

 

 

 

Update.. Ordered from these guys, after a week I got a call saying they don't have it and they would refund. 

 

Ordered instead from 'plumbing supplies delivered' and after 2 weeks it's arrived and they've sent the T12 instead of T12F so the threads are the wrong way round and it's useless. (I paid for a delivery upgrade to get it fast too) 

 

I've come to the conclusion that all plumbing suppliers are utterly useless and it looks like I'm throwing away the 40mm pipework and AAV already fitted under the sink and doing it in 32mm.

 

After a month of messing around 🤣🤣😭😭