Clypse Reservoir Refurbishment Works

Published: 07 August 2025

Manx Utilities has commenced essential refurbishment works at Clypse Reservoir, one of the Isle of Man’s four operational impounding reservoirs supplying raw water to Douglas Water Treatment Works and onward to customers in the eastern and southern regions of the Island.

During a routine inspection, one of the two critical valves at the reservoir failed to operate. Further investigation revealed a fault in the submerged valving system. To ensure continued water supply and maintain reservoir safety, both valves and their actuators will be replaced.

As the valves are located underwater, the reservoir must be fully drained to allow safe access. The draining process is already underway and is being carefully managed to protect the structural integrity of the dam and minimise water waste. It is anticipated that the reservoir will be fully emptied by mid-September, with valve replacement works scheduled to follow.

The refurbishment will be carried out by Manx Utilities’ engineers in collaboration with a specialist contractor. The valve replacement is expected to take approximately two weeks. Refilling the reservoir will take several months and is dependent on seasonal weather conditions throughout autumn and winter.  Due to the timing of the drain down activity and current healthy water stock position, this work is not envisaged to have a material impact on future water supply.

Manx Utilities is working closely with the Department of Environment, Food and Agriculture (DEFA) Inland Fisheries to safeguard the welfare of the reservoir’s fish stock during the draining process. Fish stocking at Clypse has been paused, with efforts redirected to Kerrowdhoo Reservoir to allow anglers to help reduce fish numbers at Clypse.

Manx Utilities and DEFA extend their sincere thanks to the angling community for their understanding and cooperation during this vital infrastructure project.