After replacing a section of water main, what is the first procedure that must be carried out?

The first procedure that must be carried out after replacing a section of water main is pressure testing the system. This step is critical for ensuring that the repaired or newly installed section of the water main can withstand the necessary operational pressures without any leaks. Pressure testing involves filling the pipeline with water, applying a specific pressure, and monitoring for any drops in pressure over a predetermined period. If there are no significant pressure drops, it indicates that the joints and fittings are secure, and the system is watertight.

Establishing the integrity of the system through pressure testing is essential prior to moving on to other procedures like disinfecting, flushing, or collecting water samples. It ensures that the system is safe to operate and helps prevent potential contamination that could occur if the system were to fail under pressure. Conducting the pressure testing first lays a solid foundation for the subsequent steps in the commissioning of the water main section.