What can be said about testing the DWV system with respect to water height?

The correct response highlights the requirement for at least a 10-foot head of water when testing a Drain-Waste-Vent (DWV) system. This standard ensures that the pressure created by the water height is sufficient to identify any potential leaks or weaknesses in the system effectively.

Testing with this specified water height simulates the conditions the system will encounter during normal operation. It allows for a thorough assessment of the DWV system's integrity under realistic pressure conditions. A sufficient head of water ensures that any existing defects can be detected, thereby confirming the system's reliability and safety prior to use.

Other options do not fully meet the testing standards. Minimal water may not generate enough pressure to reveal flaws, while claiming it is not necessary overlooks the importance of thorough system checks. Additionally, cutting off the water supply might not allow for a proper test since it would eliminate the necessary pressure to carry out a comprehensive evaluation, ultimately leading to undetected issues.