What must be done to joints in CPVC when installed below ground?

When installing CPVC (Chlorinated Polyvinyl Chloride) piping below ground, it's essential to ensure that the system can withstand pressure without leaks, particularly due to the potential for pressure changes in underground systems. Testing to a minimum pressure is a critical step because it verifies the integrity of the joints and the overall installation, ensuring there are no leaks before the system is buried. This testing process helps to avoid future issues that could arise from undetected leaks that might not be easily fixed once the pipes are underground.

While other options involve important practices related to plumbing installations, they do not address the specific requirement for underground CPVC joints. Testing for leaks, sealing with adhesive, and insulating for freezing are all relevant to pipe installation but do not specifically focus on the unique aspects of pressure testing necessary for underground installations.