Need help with my mains inlet water supply

[dextrous]

Some of these older stoptaps had 3/8 or even 1/4" taps fitted as drain cocks.

Principle is still the same - the op will just have to go to a plumber's merchants.

 

[doitall]

of the 2 options Dex gave you I would suggest the 611 as it is a straight fitting it is easier to use (with an elbow) to line up exactly where you want it, if you use the bent version it can sometimes be tricky to line up exactly where you want it AND not leak

Since the thread is still going.

Neither option is advisable because both fitting have a tapper thread.

The Coxex 302 has a parallel thread, which any fitting into brass, DRZ, bronze should be.

 

[dextrous]

of the 2 options Dex gave you I would suggest the 611 as it is a straight fitting it is easier to use (with an elbow) to line up exactly where you want it, if you use the bent version it can sometimes be tricky to line up exactly where you want it AND not leak

Since the thread is still going.

Neither option is advisable because both fitting have a tapper thread.

The Coxex 302 has a parallel thread, which any fitting into brass, DRZ, bronze should be.

I told the op to run away while the going was good Thanks for the info - I was unaware of that

 

[cmother1]

Aqua09 - I'm with TerryWoofkit on this. Before you go lashing out on fittings, try this simple test: remove the blanking plug you've already loosened and see if you can fit a 5p piece in the threaded hole edge-on. If you can, and there's about 1.5mm of play, it's odds-on to be 1/2" BSP. If the 5p won't go you've got one of the smaller sizes.

 

[doitall]

It's to take a 1/2" drain cock.