There are two main water piping materials found in homes that were built over the last 60 years: copper and PEX.Copper was used from the 1950s/1960s up until about 15 years ago when it started to be widely replaced by PEX – a type of plastic. Copper makes a fantastic water line, but it has limitations. Copper pipe is very susceptible to kinking and damage during installation as well as corrosion and erosion over time depending on how it was installed. Almost without exception, copper was installed under the slab in straight lengths of pipe. The straight sections do not have any fittings or connection points below the slab. These pipes come up above the slab to feed the plumbing fixtures and to branch off into other pipes at connection points called manifolds. PEX water lines completely replaced copper water lines in the mid-2000s. PEX is cheaper, quicker to install, and does not corrode like copper does. While it does have drawbacks of its own, PEX has been in use long enough to be widely considered far superior to copper for water lines. Unlike copper, PEX is mostly installed in the walls, in the attics, and between floors. For this reason, finding a slab leak on a PEX is exceptionally rare.