What materials are most commonly used for cold water piping in houses?

The most commonly used materials for cold water piping in houses are CPVC and PVC. These materials are favored due to their excellent resistance to corrosion, lightweight nature, and ease of installation. CPVC (Chlorinated Polyvinyl Chloride) can handle higher temperatures than standard PVC, making it versatile for various plumbing applications beyond just cold water. Additionally, both CPVC and PVC are cost-effective, making them accessible choices for residential plumbing systems.

In contrast, while other materials like iron and copper are also used in plumbing, they are less common for cold water systems due to their susceptibility to corrosion (in the case of iron) or higher cost and installation complexity (as with copper). Steel and aluminum are less frequently used for residential cold water lines as they are not as suitable for plumbing applications compared to CPVC and PVC. Lastly, wood and plastic are not typical choices for piping systems due to structural limitations and potential degradation over time.