Guernsey Water completes major water main upgrade in St Peter Port
- Guernsey Water has completed replacement of 80-year-old water main on Mill Street and Mansell Street
- The old cast-iron main burst twice in 2025, including flooding a local business
- 300 metres of pipe replaced with larger, more durable plastic infrastructure
- Project completed despite wettest February since 1976
- Part of £7.8m annual investment in upgrading water and wastewater systems
Guernsey Water has completed the replacement of an ageing water main beneath Mill Street and Mansell Street, marking the first major capital investment project of 2026.
The previous main, installed in 1946, had burst twice in 2025, including one incident that flooded a local business, which led to its prioritisation for renewal.
The project began on 2 January, with teams from local contractors Geomarine and Tarmac Services carrying out excavation and reinstatement work in sections. Temporary overland pipework was installed to maintain water supplies throughout the construction period.
Thousands of paving stones and deep granite cobbles were hand-lifted, cleaned and reinstated to enable safe access to the pipe below. In total, 300 metres of the old cast-iron main were removed and replaced with a larger, more durable plastic main designed to meet demand for decades to come.
The work progressed steadily despite challenging weather conditions, including the wettest February since 1976.
Capital Delivery Manager Carl Falla said: "This is the first major capital project of the year and will ensure a sufficient and resilient water supply for residents and businesses in that part of St Peter Port for the rest of the century. This year we are spending £7.8m on upgrading ageing water and wastewater systems, all part of our wider investment programme."
"I want to thank those who live and work in the area for their patience while we undertook this project. Proactive, planned works are always preferable to emergency repairs. This more durable plastic main will reduce the need for emergency interventions in the future," he added.
The new infrastructure is designed to future-proof water supplies in the area for the rest of the century, representing part of Guernsey Water's broader strategy to modernise the island's essential water infrastructure.
Guernsey Water oversees the collection, storage, treatment and distribution of drinking water to over 25,000 homes and businesses across the island, as well as the collection and safe disposal of all wastewater. The utility manages more than 100 facilities, including pumping stations, water treatment works and sea outfalls.
Q&A
Q: Why was this water main prioritised for replacement?
A: The 1946-installed main had burst twice in 2025, including one incident that flooded a local business, making its renewal a priority.
Q: How was water supply maintained during construction?
A: Temporary overland pipework was installed to maintain water supplies throughout the construction period while work was carried out in sections.
Q: What is Guernsey Water's total infrastructure investment for 2026?
A: Guernsey Water is spending £7.8 million this year on upgrading ageing water and wastewater systems as part of their wider investment programme.
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