Which type of plumbing pipe is most commonly used for residential cold water supply?

Copper is commonly used for residential cold water supply due to its durability, reliability, and long-lasting properties. It is resistant to corrosion, which is essential for maintaining water quality and preventing leaks. Copper piping can also handle high pressure and varying temperatures, making it suitable for various plumbing applications within a home.

While PVC is often used for drainage and waste systems, it is not typically suitable for hot water applications, and its use in potable water systems may be limited based on local building codes. Cast iron is primarily utilized for drainage and venting due to its strength and sound-deadening qualities, but it is generally not used for cold water supply in residential settings. PEX is gaining popularity for plumbing applications, including cold water supply, owing to its flexibility and resistance to scale and chlorine, but traditional copper piping remains a standard choice for many professionals due to familiarity and proven performance in residential plumbing systems.