Before connecting a new main to the existing system, which test must an inspector verify after flushing?

The process of connecting a new main to an existing system is critical in ensuring the safety and reliability of the water supply. After flushing the new main to remove debris and contaminants, pressure testing is essential to verify the integrity of the piping system. This test checks for leaks and ensures that the piping can withstand the pressures it will encounter during normal operation.

Pressure testing involves filling the system with water and monitoring it for any drops in pressure, which would indicate potential leaks. Successful completion of this test ensures that the new main can safely deliver water without risk of breakage or contamination from external sources.

Bacteriological testing, while important in assessing water quality, typically occurs after the initial testing to ensure the system is safe for public use post-construction. Cover testing focuses on verifying appropriate covering for trench installations, and deflection testing checks for deformation in flexible pipes under load, both of which are not directly related to the immediate task of verifying the new main's readiness for connection after flushing. Thus, pressure testing is the appropriate step to confirm the new main is safe to connect to the existing system.