What material should not be used for drinking water supply lines?

Polybutylene piping should not be used for drinking water supply lines due to its susceptibility to degradation and failure over time, especially when it is exposed to certain chemicals often found in public water supplies, such as chlorine. This type of plastic piping was widely used in residential plumbing systems from the 1970s to the mid-1990s but has since been linked to numerous leaks and failures, which can lead to significant water damage and contamination.

In contrast, the other materials mentioned—PVC, metal (such as steel or brass), and copper—are generally accepted for use in plumbing systems, including drinking water lines, because they do not exhibit the same failure characteristics as polybutylene. PVC is commonly used for non-potable water applications but some grades of PVC can be utilized for drinking water, depending on local codes. Metal piping, like copper and brass, is durable and resistant to many chemicals, making them a reliable option for drinking water supplies.