Tee off mains water

[Autoreclose]

I want to tee off my underground water supply to feed into my new downstairs toilet at front of house.
The water pipe feeds my house to the rear into kitchen.
The 3-bed house was built in 1969 and the existing pipe is black plastic.
I need to buy all my joints in advance so I don't leave the hole exposed too long.
I only have to lift block pavings and dig down, the question is What is the size of the black pipe?
Was there a standard size used in those days, my area is South Manchester.

 

[kirkgas]

if you know it is black plastic does that mean you can see a bit of it? eg where it joins the valve, if so can you not measure it?

 

[ivixor]

No idea about the pipe, but personally I'd much sooner lift some floorboards for an internal connection before digging out to who knows how deep, making an underground joint, digging horizontally under house foundations, not to mention having to break/drill the floor slab of the house first. Just my feeling, apologies if that's not useful/not relevant.

 

[Autoreclose]

if you know it is black plastic does that mean you can see a bit of it? eg where it joins the valve, if so can you not measure it?

I can't see the pipe now, it was visible near the stop tap in the kitchen before the units were installed 9 years ago, can't see it any more unless take corner unit out.
Having read some other emails I gather the black pipe is called alkathene.
I want a new entry to the front of house since it is only about 6 metres.
I am worried about the black pipe since I have noticed black specks about 1mm size.
If I rub the outlet of the Kitchen tap with kitchen role it collect a number of these black specks.
After a couple of rubs it clears, but after a week some more will have accumalated.
I wonder if the black pipe is slowly breaking down internally.
By taking a new supply into the front of house (downstairs toilet) I could if neccessary connect to internal water supply.
The existing black pipe could then be disconnected if it proves faulty, it happens to run under the kitchen floor which is concrete.