Connecting water supply to a 15mm plastic thread on cistern.

[I_aint_no_plumber]

I am about to connect my new close-coupled cistern to the water supply.
The cistern appears to have a plastic 15mm thread protruding vertically.

What connection do I need to use to join my incoming 15mm copper pipe to this 15mm plastic thread and do I need some plastic pipe in between?

 

[ChrisR]

It's not at all unreasonable to think it might be a "15mm" thread, but it's probably either 1/2 inch or 3/8 inch. If it's the same size and thread you get on a 15mm compression fitting then it's 1/2" (about 20mm outside diameter). That's the same as a basin tap, so you use a tap connector fitting, which would be one of these for a cistern -"Service valve" nb it has an isoloating valve in it

Or if things don't line up so well, one of these would be fine. You can get them in various lengths. Some have iso valves, some push-fit onto the copper (or plastic) pipe, some have a compression pipe fitting. They just screw onto the end of your cistern fitting.

If you have a 3/8" thread, better visit a merchant and get an adaptor to 1/2" perhaps.

 

[I_aint_no_plumber]

Thanks for that. I assume that screwing a metal female connector onto a plastic male thread isn't a problem?


PS I wish I knew more about what I was doing - I've run out of towels

 

[Nige F]

Don`t assume that Use extreme care and the parts Chris has suggested will be fine.....and don`t smother the Male thread with ptfe..........makes it worse.......leave it clean and "feel" the threads together.....easy to cross