Plumbing

Pipes leach chemicals into the water that flows through them -- some more than others. Below is a link to a study comparing different pipes and the chemicals they leach into the water. In general, it seems that CPVC piping and copper piping (with silver flux) are probably the best options, for either hot or cold applications.

Impact of Polymeric Plumbing Materials on Drinking Water Quality and Aesthetics by Timothy Heim