Guernsey Water Progresses Water Main Replacement into Mansell Street

Guernsey Water has progressed its first major infrastructure project of the year from Mill Street into Mansell Street. All paving has now been re-laid and full pedestrian access through Mill Street restored. All businesses could be accessed throughout.   

The project involves the replacement of an ageing water main, originally laid in 1946. The existing pipe burst twice in 2025 and has been prioritised for replacement to reduce the risk of further unplanned failures, disruption and emergency repairs.  

Works in Mansell Street require the temporary removal of traditional granite cobbles to allow access to the main beneath. These cobbles are being carefully lifted, cleaned and stored for reinstatement once the new watermain has been replaced.  

The replacement main is a larger, more durable pipe designed to better meet future demand. Once complete, the new infrastructure will secure reliable water supplies in the area for the rest of the 21st Century.  

Approximately 90 metres of trench are currently open, with works progressing well. Recent improvements in weather conditions have supported steady progress, but owing to weather conditions and the time taken to lift and lay cobbles and paving stones, the utility is behind schedule. 

Carl Falla, Capital Delivery Manager at Guernsey Water, said:  

“The existing main in Mansell Street had reached the end of its operational life. Replacing it now as part of a planned programme allows us to reduce the likelihood of future bursts and avoid the greater disruption that emergency repairs can cause. While this is a complex site, particularly due to the cobbled surface and supporting access to businesses, the project is progressing well. We thank everyone for their patience as we undertake this vital work.”  

Access to all businesses in Mansell Street is being maintained throughout the works. However, for safety reasons, it is not possible for pedestrians to pass through the full length of the site. Clearly signed diversions are in place.  

Guernsey Water is using local contractors wherever possible to keep skills and money within our economy. Geomarine has been appointed to carry out the water main replacement, with Tarmac Services responsible for lifting, cleaning and reinstating the cobbles.  

The Mansell Street water main replacement is the first project in Guernsey Water’s 12-year, £130 million investment programme in water and wastewater networks, with £7.8 million planned for delivery in 2026.