Water supply pipe diameter and reducer

2 Aug 2019
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United Kingdom
The communication pipe to our pavement stopcock is being upgraded to 25mm MDPE from 15mm. That's a run of about 6m

I plan to have a 15m run in 32mm MDPE to the house stopcock, done by moling. My plumber recommends 32mm over 25mm to future proof the supply pipe and minimize dynamic pressure drops. Calculations confirm there is a material improvement in using 32mm over 25mm.

I presume Thames water will terminate in with a stopcock expecting a 25mm pipe.

Assuming it would be best to prepare for that, what kind of reducer would I need to have to fit to a TW 25mm stopcock?

Can you have a stopcock with 32mm one side, 25mm?

I just want to be able to deal with issues in case the TW fitters are difficult or in difficulty ("Don't have the parts" etc)
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All the ones I see are 25mm on the house side connected to the supply by which ever fitting is required.

They should have a 25-32 for connecting to your new pipe.

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