Water main pipe size

Richuu · 1 Dec 2006

I need to move the main stop cock inside the house, meaning I will have a joint, some more plastic pipe, then the stop cock and onto 15mm copper.

I measured the main incoming pipe, and it 'appears' to be 22mm black MDPE. However, 22mm MDPE doesn't appear to exist - only 20 or 25. The house was built mid-80's, but I've read elsewhere on here that before the 20 and 25mm pipes "there were previous sizes". I'm wondering if my "22mm" pipe is one of those, or, more likely (or should I say 'hopefully'), it's 20mm, but I've measured it at it's widest point where it's bulged a bit on the bend.

Any other theories?

libby lou lou · 1 Dec 2006

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I need to move the main stop cock inside the house, meaning I will have a joint,

Move the stopcock first,then have a joint

Richuu · 1 Dec 2006

Good plan....

BoxBasher · 1 Dec 2006

If it is black then it won't be MDPE.

It is more than likely black alkethene, may be PVC. Try a plumbers merchant for fittings, although you may find the measurements are actually imperial.
When you move the stopcock, install a drain valve after it, this will make things easier if you ever have a problem in the future.

TicklyT · 1 Dec 2006

Can you leave the old stopcock as is, treat it as a fancy looking compression joint with a handle on top that doesn't do anything, and run on from there in copper to a new stopcock wherever you need it?

Tom JE · 1 Dec 2006

Thats what i did when my original stop cock seized instead of trying to find one to fit the original pipe. I left it on place and just fitted my new stop cock and pipe work from there on.

BoxBasher · 1 Dec 2006

TicklyT said:
Can you leave the old stopcock as is, treat it as a fancy looking compression joint with a handle on top that doesn't do anything, and run on from there in copper to a new stopcock wherever you need it?

You can, but you're b*ggered if you box it in. Most common place for a blockage is inside a stoptap/under the jumper. Screwed if you can't get at it. Much better to cut out and piece through

keego · 2 Dec 2006

Black poly pipe is imperial so yours would be 3/4", probably class C or D.
It will be the same fitting just a different insert, buy one of each just to be sure.

doitall · 2 Dec 2006

More likely to be 1/2" class C or D.

Look for some writing on the pipe and it will tell you.

htgeng · 2 Dec 2006

Tom JE said:
Thats what i did when my original stop cock seized instead of trying to find one to fit the original pipe. I left it on place and just fitted my new stop cock and pipe work from there on.

That will work ok, but there will be a flow restriction in place from the old tap. It may not be significant, but can't you isolate at the street and do a proper job?

keego · 2 Dec 2006

Richuu said:
However, 22mm MDPE doesn't appear to exist - only 20 or 25. The house was built mid-80's, but I've read elsewhere on here that before the 20 and 25mm pipes "there were previous sizes". I'm wondering if my "22mm" pipe is one of those

I only spent 18 years working for the water board, so I might not be as knowledgeable as doitall but 22mm od black poly pipe is 3/4"

doitall · 2 Dec 2006

keego said:
Richuu said:

However, 22mm MDPE doesn't appear to exist - only 20 or 25. The house was built mid-80's, but I've read elsewhere on here that before the 20 and 25mm pipes "there were previous sizes". I'm wondering if my "22mm" pipe is one of those

Click to expand...

I only spent 18 years working for the water board, so I might not be as knowledgeable as doitall but 22mm od black poly pipe is 3/4"

You may be right keego

after 48years one does tend to forget.

Class C & D BS 1972/BS 3284

20mm 1/2" (3/8" LCD)
25mm 3/4"
32mm 1"
40mm 11/4"
50mm 11/2"
63mm 2"

The first Number being the fitting size.

Internal components colour for inserts.
BS 1972:61, IRS 134 N.G Red, IRS 135 H.G Pale Blue.
BS 1972, LD.C Light Blue, LD.D Light Green.
BS 3284, HD.C Dark Blue, HD.D Dark Green.

chrishutt · 2 Dec 2006

As DIA said, it's ½" black low density polythene pipe (BS 1972) which has an OD of 21.5mm. (same as ¾" imperial copper). This is obviously the size that the poster has.

keego · 2 Dec 2006

doitall said:
keego said:

Richuu said:

However, 22mm MDPE doesn't appear to exist - only 20 or 25. The house was built mid-80's, but I've read elsewhere on here that before the 20 and 25mm pipes "there were previous sizes". I'm wondering if my "22mm" pipe is one of those

Click to expand...

I only spent 18 years working for the water board, so I might not be as knowledgeable as doitall but 22mm od black poly pipe is 3/4"

Click to expand...

You may be right keego after 48years one does tend to forget.

Class C & D BS 1972/BS 3284

20mm 1/2" (3/8" LCD)
25mm 3/4"
32mm 1"
40mm 11/4"
50mm 11/2"
63mm 2"

The first Number being the fitting size.

Internal components colour for inserts.
BS 1972:61, IRS 134 N.G Red, IRS 135 H.G Pale Blue.
BS 1972, LD.C Light Blue, LD.D Light Green.
BS 3284, HD.C Dark Blue, HD.D Dark Green.

It's allowed m8, I've only got another 6 years to catch up with you providing I dont have another heart attack!. Each to their own, after 18 years playing around with the underground stuff before moving on to heating, I'll continue advising about what I know & you do the same.
It was no dig at you ,just trying to pass on what I know to other people.

keego · 2 Dec 2006

& it would help if the OP would state if his measurments were OD or ID!!

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Water main pipe size

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