Which sequence lists the treatment steps for a water main break?

• A. Apply liberal quantities of hypochlorite to the trench; Swab the interior of all new components with a one-percent hypochlorite solution; Flush the section after the repair
• B. Swab the interior of all new components with a one-percent hypochlorite solution; Apply liberal quantities of hypochlorite to the trench; Flush the section after the repair
• C. Apply liberal quantities of hypochlorite to the trench; Swab the interior of all new components with a one-percent hypochlorite solution; Flush the section after the repair
• D. Apply liberal quantities of hypochlorite to the trench; Flush the section after the repair; Swab the interior of all new components with a one-percent hypochlorite solution

Answer: (C)

The sequence for disinfecting a repaired water main follows a logical flow from outside to inside to ensure no contamination can enter the water as the system is reassembled. First, apply hypochlorite to the trench. This cleans and disinfects the excavation area and surrounding soil, reducing the chance that contaminants in the backfill or soil can enter the new section during installation. Next, swab the interior of all new components with a 1% hypochlorite solution. Cleaning the internal surfaces of the new components ensures that any residues from fabrication or handling do not carry bacteria into the water as service resumes. Finally, flush the section after the repair to purge the system of chlorine residuals and any loosened debris, verifying that the water leaving the repaired main meets safety standards. This order minimizes recontamination and ensures the repaired section delivers safe water.