Pipe Installation, Repair, and Maintenance
Installation, disinfection, and repair practice
Installation quality determines long-term performance. Trench width and depth, bedding, and uniform compaction of backfill protect the pipe; improper bedding causes point loading and breaks. Cover must be below frost and deep enough for traffic loads. Thrust blocks or restrained joints hold bends and tees against pressure. Tapping a live main uses a tapping sleeve and machine; wet taps require careful planning and disinfection of tools and fittings.
New and repaired mains must be disinfected and sampled before service. A common practice is to chlorinate the new main with a strong dose (often 25–50 mg/L) for 24 hours, flush to remove chlorinated water - dechlorinating before discharge where required - and then collect bacteriological samples. Repair clamps, sleeves, and joint seals restore service, but the area must be flushed and sampled after a repair, especially after a main break where soil or debris may enter.
Maintenance is proactive: valve exercising prevents seized valves, leak detection finds losses before they become breaks, and unidirectional flushing scours sediment using controlled velocity and valve sequencing. Shutdowns need a plan - valves to close, customers to notify, and a boil-water notice if pressure falls or contamination is possible.
Traps: skipping disinfection because the main is “small”; discharging highly chlorinated flush water without dechlorination; assuming a repair is complete once water flows; failing to exercise valves until an emergency.
Rule of thumb: after any repair that depressurizes a main, flush until clear and sample for coliforms before returning the area to normal service.