Copper is a common choice when it comes to looking for materials for plumbing jobs. 15mm Copper Pipe that you can find from Watkins & Powis for example can be used in a variety of plumbing needs. Not only is it able to be cut and shaped incredibly easily but it is also a great conductor of heat so it can be used in elements of heating systems. Copper is also unaffected by the oxidisation that can occur when metal is in contact with water. This is why you often see a green patina on the outside of plumbing pipes.
Copper can be more expensive than PVC but it requires much less upkeep and has lots of long term benefits. It is non-toxic which is why it is used for channeling water into our taps both for use to bathe and wash in as well as providing us with drinking water.
As well as being non-toxic the surface of copper pipes is not one that a number of bacteria and organisms like. This means it is harder for these bacteria to thrive in these environments. In contrast PVC can leak chemicals into the water and it can also be a great place for bacteria to build up. This is why PVC pipes are mostly used to remove waste water from our homes.