What it means
Main installation or repair can introduce soil, debris, or microorganisms. Disinfection procedures generally involve cleaning, chlorination, contact time, flushing, residual checks, and bacteriological sampling based on local requirements.
What operators watch
- Keep contamination out during the repair whenever possible.
- Follow utility procedures for chlorine strength, contact time, flushing, and sampling.
- Do not return a main to service until required checks are complete.
Common exam traps
- Skipping flushing before or after chlorination.
- Confusing routine distribution residual with main-disinfection concentration.
- Ignoring bacteriological sampling requirements.
Field example
After a main break, crews isolate the area, repair the pipe, flush, disinfect as required, and collect samples before normal service is restored.
