£12m Derg Water Treatment Upgrades Move To Final Stage

The £12 million upgrade at Derg Water Treatment Works is approaching the final stages of construction.

Drinking Water Inspectorate (DWI) colleagues visited the NI Water site to see first hand the progress of the major project.

The purpose of the visit was to give an overview of the new plant and construction process, as well as a chance to see the new tanks before they are fully commissioned and filled up with water.

Once complete, this essential investment will not only improve the water quality within the Derg network but will also provide additional security of the water supply to our customers in the Castlederg and Strabane supply area and further afield.


The existing Derg Water Treatment Works was built in 2002 and replaced the old works a few hundred meters from the current site. This £12 million upgrade, which is now in the final stages, involved the construction of a new clarification process and an activated carbon addition, which will further enhance water treatment at the Derg plant.

The 18-month construction contract is being undertaken by Castlederg-based Lowry Building & Civil Engineering as part of the wider DLG Water Ltd, with RPS providing project management specialist support.

Once complete, the project will also improve herbicide and organics removal at the plant, improving the efficiency of the existing works and will increase the throughput of Derg WTW to over 26 million litres of water per day from the River Derg and more recently, Strule. The works serves the Strabane and Omagh areas as well as supplying water into the Fermanagh area.