UK Copper Pipe Sizes — Table X & Y

Table X (previously Table X in BS 2871) is the thinner-walled standard pipe used for most domestic plumbing. Table Y has thicker walls for higher-pressure applications or where the pipe will be bent extensively. For typical domestic hot and cold water, central heating and gas installations, Table X is standard. Table Y is used where higher pressure ratings or additional protection against corrosion is needed.

Standard domestic sizes: 15 mm for individual hot and cold taps, basins and radiator feeds; 22 mm for main cold water distribution, hot water cylinder connections and main heating flow/return; 28 mm for main cold water supply from the mains, boiler connections and larger heating circuits; 8 mm and 10 mm for micro-bore heating systems and individual radiator connections.

Yes, using push-fit fittings (e.g. JG Speedfit, Hep2O) that accept both copper and plastic pipe, or with purpose-made copper-to-plastic adaptors. When connecting to push-fit on copper pipe, ensure the pipe end is clean, round and free of burrs. Some push-fit systems require a pipe insert (liner) in the plastic pipe but not in the copper pipe.

Plastic pipe (push-fit, barrier pipe, PEX) is increasingly used for domestic plumbing due to speed of installation and lower cost. However, copper remains preferred for exposed pipework, boiler connections, gas installations (where copper is mandatory), and situations requiring UV resistance or higher temperature ratings. Many plumbers use a combination of both.