UTL/Water/TBT-UTL-011

Water Main Repair Under Pressure

Utilities & Network Infrastructure › Water › Water Main Repair Under Pressure

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Water main repairs under pressure are carried out when it is not possible to isolate the supply to customers.
The pipe remains live with water pressure during the repair, creating burst and flooding risks.
Repair methods include clamp-on fittings, live tapping, pipe inserts, and epoxy wrap systems.
Water under mains pressure can erupt suddenly when fittings are loosened, flooding the excavation.
Working in a flooded excavation while handling tools creates drowning and electrical hazard risks.
Operatives must be specifically trained and competent in live water main repair techniques.
The water company or network operator must authorise all live repair work before it begins.
Contamination risk to the water supply during repair requires strict hygiene and disinfection controls.
DWI (Drinking Water Inspectorate) regulations require that repairs do not compromise water quality.
The Water Supply (Water Fittings) Regulations 1999 govern all connections and repairs to water mains.

Flooding risk	Pressurised water erupting from a failed repair floods the excavation in seconds, trapping and drowning workers.
Public health	Contamination entering the water supply during repair causes illness outbreaks affecting thousands of customers.
Legal compliance	DWI and water company standards require trained, competent operatives using approved methods and materials.

Don't

Obtain water company authorisation before starting any live main repair work.
Use only trained and competent operatives for live water main repair tasks.
Have pumps ready to manage water inflow if the repair fails during the work.
Follow strict hygiene procedures to prevent contamination entering the supply.
Use only approved repair fittings and materials that meet water supply standards.
Ensure the excavation has adequate egress routes in case of sudden flooding.
Disinfect all tools and fittings that will contact the water supply during repair.
Monitor water pressure and flow throughout the repair operation continuously.
Brief the team on the emergency procedure if the live repair fails.
Flush and test the repaired section before returning it to normal supply.

DON'T attempt live main repair without water company authorisation and training.
DON'T use non-approved fittings or materials that could contaminate the supply.
DON'T enter a flooded excavation to continue a repair; pump it out first.
DON'T touch food, drink, or your face with hands that have contacted mains water.
DON'T loosen fittings on a pressurised main without being prepared for water release.
DON'T bypass the disinfection procedure for tools contacting the water supply.
DON'T leave a partially completed repair unattended on a live water main.
DON'T reconnect the supply until flushing and bacteriological testing confirm quality.
DON'T work in an excavation without a means of rapid egress if water surges.
DON'T assume pressure has equalised; check before removing any temporary fittings.

See also: Water Main Installation Safety | Water Service Connections

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