A 25mm to 15mm adapter needed.

  • Thread starter richard7761
  • Start date


Hi. I have a quality stop cock that I ought to use. I'm left it because the local council (the beggars) never completed what they started. Anyway, on the inlet side it takes a blue plastic pipe of 25mm dia. that has an olive on it. Tighten up the nut and you get a seal. On the outlet side the same arrangement, but it's for 15mm copper pipe.

Because my water supply pipe is 15mm copper I need some sort of adapter, so this 15mm pipe will fit onto the 25mm side of the stop cock. I was hoping I could buy a brass adapter, but I have not identified a product.

Can anyone please tell me what adapter you would use in the circumstances. Thanks. Rich.
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Well, that's what I thought the message probably was. Because there isn't such a thing as a brass adapter or coupler from 25mm to 15mm, not even a straight coupler. It's not possible to connect a stop cock that accepts a 25mm MDPE pipe to a 15mm copper pipe, as I say, not even via a straight coupler.


Just a thing about the stop cock that I have, it's got a drain off.

Maybe council thought it needed to fit that type. But, I don't think I have to. Can drain to sink about 2 foot above stop cock.

I might even have a K787DZR! Quite expensive if so. ;)


I think my best bet is to contact Pegler, and tell them what I'm trying to do.
22 Jul 2009
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United Kingdom
Do I have this correct.

You have a 15mm incoming main and 15mm internal pipework but you are trying to use a 25mm to 15mm stopcock just because you have it lying around?

If that's the case, do what has already been suggested and use a 15mm stoptap. Its the correct part for the job and not expensive. What you are trying to do is pointless and a bodge.


Yes, you have it right. I'll take the advice and get a stop cock for the job.

Put the stop cock I got on Ebay, might get something for it. It's got a drain off but don't think that means much. Rich

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