Arizona Plumbing Practice Exam 2025 – Complete Preparation Guide

The preference for PEX or PVC piping for underground water lines stems from their durability, resistance to corrosion, and flexibility. PEX (cross-linked polyethylene) is particularly advantageous because it can expand and contract without breaking, making it highly durable against freezing temperatures and ground movement. This flexibility allows for easier installation in various underground applications.

PVC (polyvinyl chloride) is also a strong choice for underground water lines due to its resistance to chemicals, rust, and corrosion, allowing it to last significantly longer than many traditional materials. Both PEX and PVC boast lower weights compared to metal options, making them easier to handle and install without compromising on strength.

In contrast, other options, such as CPVC, while also durable, are typically used for hot water lines rather than cold water or general underground applications. Galvanized steel and cast iron, while once popular for water lines, are susceptible to corrosion and rust over time, which can lead to leaks and water quality issues. Their weight and rigidity can also complicate installation processes compared to PEX and PVC. Thus, PEX or PVC stands out as the most effective choice for underground water lines, highlighting their practical advantages in durability and installation ease.