When should a new water main be disinfected?

The disinfection of a new water main is critical to ensure that it is free from harmful bacteria and pathogens before it is put into service. The correct timing for this disinfection is when the pipe is installed and initially filled with water. This approach allows the disinfection processes, such as chlorination, to effectively contact the internal surfaces of the new pipe while it is filled with water.

Disinfecting at this stage is essential because it mitigates the risks of any contaminants that may have entered during installation, ensuring that the water flowing through the main meets health and safety standards. The surfaces are still clean from construction, making this the optimal time for disinfection before the system experiences any prolonged use.

Once the new main is operational or after routine inspections, it would already be in use, making it impractical for a thorough disinfection to occur without causing service interruptions or affecting water quality. While disinfection before installation might seem logical, it would not be effective since the pipe itself is not yet in a state that can be properly disinfected without first being installed and filled.