Copper piping has been around for a long time because it has some very favorable qualities when installed correctly. It used to be relatively inexpensive, easy to install and durable. Copper piping is not perfect though, and is prone to weakening and failure due to high acid (low pH) content of water. Another source of failure is improper installation and sweating of the pipe joints. Green corrosion on a pipe is caused by the oxidation of the copper itself. It can be caused by a water leak, or not cleaning the pipe properly after using an acid flux to sweat the joint. White build up at a joint can be a sign of calcification of the joint left behind by a very slow leak or external condensation, the use of a poor quality solder, or zincification (corrosion of a brass fitting). In general, copper pipe joints should not exhibit either green or white corrosion like the picture on the left, but should be neat and clean like the picture on the right. If you have copper piping that doesn't look healthy, you may want us to inspect them to be safe.
