To lay pipe underground outside, you will need some MDPE (blue) pipe in 20 or 25mm size. Adaptors to join to 15mm copper at the appliance end, and in the house. Approprate joints to route pipe through wall and to where you need it. Appliance connection valve at WM end, isolating valve (15mm) to control supply before it leaves house. Probably a compression or speedfit "T" fitting in 15 mm size to join to house supply.
Bury external pipe at least 18" to protect from frost.
Other things needed; some 15mm copper pipe (sold in 3m lengths), pipe clips to secure, adjustable spanners (2), ptfe tape, pipe cutter for copper.
Try local plumbers merchants. Treat yourself to a DIY plumbing book.
Roy, December 2008
