MDPE coming off existing copper pipe - help appreciated

5 Mar 2012
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United Kingdom

There are loads of discussions on here and around the web about connecting one piece of copper pipe to one piece of MDPE, but none (that I could find, anyway :oops: ) regarding the process of branching an MDPE pipe off an existing copper supply, so here is my question.

There's an outside tap which is between the mains water valve, and the house, and I want to add another outside tap a looooong way (maybe around 20m) away. The existing fittings are all copper, but nowadays I believe MDPE is the easiest and cheapest solution, so I would like to add a branch off of the mains for another tap, and potentially in the future, automatic animal drinkers, troughs etc.

Can I have suggestions as to the best way to go about this - in particular how to branch off of the existing copper pipe and connect an MDPE to it, and any other suggestions you may have.

Also, is it better to keep the joins underground to avoid freezing over cold (scottish) winters?
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Presuming your copper is 15mm and your MDPE is 20mm, fit a 15mm x 1/2" female branch tee into the copper, screw a 20mm x 1/2" male adaptor into the branch.



You could fit a self-tapping washing machine valve and a 20mm x 3/4" female adaptor. Most pros don’t like the self-tappers, though.

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