Old polythene pipe sizes

raimiska · 29-04-2025 10:31PM #1

If a pipe measures 21 mm, is it safe to assume it's Irish 3/4 size? I've got an old polythene pipe from the mains going up to the attic cold storage in one run. Would buying inserts and 3/4 compression fittings be the right approach if I intend to tee into the pipe?

I'm intending to tee into it to supply an electric shower with mains pressure. Before, there was pipework coming from the attic storage for a pumped electric shower. The new one states mains pressure only, hence why I intend to get water flow from mains instead. Is that the correct approach? Wiring and grounding would be done by a certified electrician/plumber, so I'm not worried about that. I just want to do the plumbing for the shower and also one cold tap, since previously it was supplied straight from the attic storage that was full of pitch black muck.

dathi · 30-04-2025 07:20AM

https://www.beattys.ie/products/1-polyadaptor-complete?currency=EUR&variant=39434049519660&utm_source=google&utm_medium=cpc&utm_campaign=Google%20Shopping&stkn=379c50276a65&gad_source=1&gad_campaignid=20227715727&gbraid=0AAAAAD1mb6KWKB1iWAykxm7dH8WuFkRMJ&gclid=Cj0KCQjwlMfABhCWARIsADGXdy8j5ABLO04_jKnozVyp-nCTEJLUA4NlUoCvzoRBvzbIJvI4B5t2WKsaAr99EALw_wcB

if the pipe is black plastic then it is hydrodare pipe and you will need an insert like the above to use brass fittings you will get in any plumbing supplies the above one is for 1" pipe not 3/4" if it is tan coloured pipe then it is qualplex and just needs an insert in the pipe

raimiska · 30-04-2025 06:17PM

Yeah is black and quite flexible as well.

Replacing the pipe with qualpex was my original idea but I'm not sure if it's worth the extra work. Can't tell when it was installed and how many years it's got left.

I've attached 2 pics for reference. One where it connects under the sink to mains and one in the attic just for clearer view of the material.

Old polythene pipe sizes

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