Which material is commonly used for water supply lines in residential plumbing?

Copper is commonly used for water supply lines in residential plumbing due to its durability, resistance to corrosion, and ability to withstand high temperatures. It has been a traditional choice for years because it does not leach harmful substances into the water, making it safe for drinking supplies. Additionally, copper piping can be easily soldered together, allowing for secure connections that are critical for maintaining a leak-free system.

While plastic and PVC are often used for drain, waste, and vent (DWV) applications, as well as in certain pressurized systems, they are generally not preferred for potable water supply lines because of concerns regarding temperature limits and potential leaching over time. Steel is also used in some plumbing applications, particularly for gas lines or specific industrial uses, but it is more prone to corrosion unless properly treated. Therefore, copper remains the standard choice for reliable and safe water supply lines in residential settings.