Copper and polybutylene are common materials in household piping, but they have very different characteristics. Polybutylene was used for two decades as an innovative material for plumbing, but has fallen out of favour since the 1990s.
Copper is a naturally occurring malleable metal, extracted from ore and refined for industrial use. Most homes in the U.S. have copper piping. Polybutylene is a synthetic plastic. It was used in the U.S. for water pipes from 1978 to 1995.
If the plumbing in your house is an inch or a half inch in diameter, the interior pipes in your home are grey or white and the exterior pipes are blue, black or grey, they are probably made of polybutylene. Copper has a distinctive red-brown colour and gleam. Some homes have a mixture of both, or copper parts used to feed fixtures on a polybutylene pipe.
Polybutylene is a cheaper material than copper and is easier to install; however, copper pipes last longer than polybutylene plumbing. Since polybutylene was first used in homes, weaknesses in structure over time have been found. This could be due to oxidants in the water altering the chemical structure of the plastic, causing pipes to break. This does not occur with copper, as it is an inert metal.