Water main installation involves laying and jointing ductile iron, HDPE, or PVC pipes in trenches, followed by pressure testing, chlorination, and flushing before connection to the live network. The work combines excavation hazards, heavy pipe handling, pressure testing risks, and chemical exposure during chlorination. Connections to the live network involve working under pressure and coordination with the water company. Only operatives with the relevant water company authorisation may work on potable water supply infrastructure.
Key Hazards
Trench collapse during pipe laying in narrow utility excavations
Pressurised pipe failure during hydrostatic testing causing violent jet release
Chemical exposure during chlorination using concentrated sodium hypochlorite
Heavy pipe handling injuries from ductile iron and large-diameter HDPE sections
Control Measures
Support all trenches with shoring or trench boxes before entering for pipe installation.
Use mechanical lifting equipment for handling heavy ductile iron pipes and fittings.
Carry out pressure testing with clear exclusion zones and trained test personnel only.
Wear chemical-resistant PPE including goggles and gloves when handling chlorination chemicals.
Flush and disinfect all new mains in accordance with the water company procedure before connection.
Ensure all operatives hold the relevant EUSR or water company authorisation for the work being done.
Protect all pipe joints and fittings from contamination during installation to maintain hygiene standards.
Record all test results, chlorination data, and bacteriological sample results for the commissioning file.
Coordinate live connections with the water company and follow their specific safe working procedures.
Emergency / Rescue
If a pressurised main fails during testing, evacuate the exclusion zone immediately. If chlorination chemicals contact skin or eyes, flush with clean water for at least 20 minutes. Call 999 for any injuries.
Remember
Water main trenches require proper support before anyone enters for pipe installation.
Pressure testing exclusion zones must be strictly maintained to protect against violent pipe failure.
Chlorination chemicals are corrosive and cause severe burns to skin and eyes on contact.
Only EUSR-qualified or water company authorised operatives may work on potable water mains.
New mains must pass bacteriological testing before being connected to the live supply network.
All test results and commissioning records must be completed accurately for the handover file.