A major island reservoir will have to be drained after a fault was found in the valving system during a routine inspection.

Manx Utilities has had to start essential refurbishment works at Clypse Reservoir in Onchan which is 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 east and south of the island.

In a statement, Manx Utilities said: ‘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 but it will take sometime for the reservoir to be refilled.

Manx Utilities said: ‘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.

‘We are working closely with the Department of Environment, Food and Agriculture 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.’