In the past, plumbing pipes were often iron or lead. Each has its advantages and disadvantages - lead, for example, is easy to bend but it requires skill to join, it is expensive and lead plumbing systems have been a contributory factor towards lead poisoning in soft water areas. Nowadays, most plumbing pipes are copper, though stainless steel and rigid and flexible plastics are sometimes used. Plastic pipe is becoming more common for the cold water service pipe in new houses.
Copper pipe(pipe fitting) is generally easily available and fairly easy to work with. It comes in various sizes and is sized by its outside diameter - 15mm, 22mm and 28mm are the most common sizes. Main runs and pipes feeding bath taps and the hot water cylinder are usually 22mm pipe. Pipes to all other taps are usually 15mm in diameter. The 28mm size might be used for some boiler pipes and sometimes for feeding the hot water cylinder (instead of 22mm pipe).
Copper pipe can be cut with a fine-toothed hacksaw or with a special pipe cutting tool. Care must be taken when using a hacksaw to cut the end of the pipe exactly square, and the cut must be filed smooth both inside and out. A pipe cutter tends to leave a burr on the inside of the pipe - this should be filed off or removed with the pointed reamer on the pipe cutter.
Copper pipe can be bent fairly readily but it must be supported during the process or it will kink. Smaller diameters can be bent by hand with the aid of a bending spring. This is a stiff metal coil of nearly the same diameter as the inside of the pipe. It is pushed into the pipe around the point where the bend is to be made and supports the pipe during bending. The spring should be compressed a little - by turning it - before attempting to with¬draw it. You need one for each size of copper pipe. Pipe can also be bent using a bending machine.
For most small plumbing jobs, bending springs are probably all that you need -with these you can make bends of different radii, make bends near the end of a length of pipe (but with difficulty) and bend pipes up to and including those of 22mm diameter. They are also inexpensive to buy, but require effort to use.
For large plumbing jobs involving a lot of bending, a machine is worth having they are very expensive to buy but can be hired. A machine takes most of the effort out of bending any size of pipe but the radius of the bend is fixed, and it requires practice to get the bend in the right place.
You can get corrugated hand-bendable pipe in lengths up to 550mm. This is easy to bend and is ideal for use in awkward situations - such as making the final connections to bath taps. Some hand-bendable pipes come with a tap connector already fitted.