Originally popular due to its high malleabilty, its use has been abandoned because of the highly toxic products that result when even slightly acidic water reacts with it.
Most modern domestic water piping is now in copper (although plastic has become the material of choice in recent applications). Copper is a good material because it is durable, light and easy to work with. Copper pipes are usually joined with the use of compression fittings or soldered (either by hand or using Yorkshire Fittings).
The use of lead in solders has been subject to the same criticisms as lead pipes, so lead-free solders are now in use. Green residues in bathroom fixtures are indicative of acidic corrosion in copper pipes.
Copper pipes usually mate with plastic pipes (e.g. the feed into a power shower) with push fit fittings.
High strength plastic piping is sometimes used for both mains water and gas feeds, its main strengths being its resistance to the corrosive effects of being underground and its light weight.
In domestic plumbing, several types of plastic are used. These include rigid PVC for cold water and waste systems, flexible polyethylene for cold water, flexible polybutylene (PB) for hot and cold water. Domestic plastic pipes with hot water feeds of the CPVC type use a special solvent.
Rigid ABS and PP plastic are used for most of the waste system including vent stacks, and have largely replaced the much heavier cast iron pipes.
Domestic plastic pipes are generally glued, called solvent welding; however, threaded, push-fit or speed-fit fixings are sometimes used. Compression fittings are common when the plastic must connect with metallic pipes or fixtures.
Commonly used in older houses and for gas lines. Threaded steel pipes are heavy and prone to rusting and leaking, especially in hot water lines, but continue as the material of choice for domestic small diameter gas lines.
