Irish Water gets go-ahead for €80m reservoir in south Dublin

An Bord Pleanála approves new covered facility amid water quality concerns

An Bord Pleanála has given Irish Water permission to construct a new €80 million covered reservoir in Stillorgan, south Co Dublin.

The current Stillorgan reservoir site has supplied drinking water to the local community for 150 years, but Irish Water argued that a covered reservoir was “essential to safeguard the quality of the drinking water for 200,000 customers”.

Planning permission was granted for the project by Dún Laoghaire-Rathdown County Council last June subject to the temporary provision of a publicly accessible open space on a landscaped area at the existing Stillorgan site.

Irish Water appealed this planning condition as it claimed the locations of the decommissioned reservoirs needed to be maintained for future water services infrastructure to secure drinking water for the community.


An Bord Pleanála ultimately accepted the utility should be allowed retain the entire site for this future development.

The development includes draining of one of the existing reservoirs and the construction of the covered reservoir. Once the new covered reservoir is operational, the other two open reservoirs will be decommissioned, and landscaping of the site will take place but without public access at this time.

Growth to 2031

The covered reservoir, due to be operational by 2020, will have the capacity to support future growth in the area to 2031, Irish Water said.

The remainder of the site will be retained for future water services infrastructure to secure the long-term supply of drinking water for much of south Dublin.

Irish Water has invested €3.4 million to improve disinfection of drinking water stored in the Stillorgan reservoir, which enabled it to be removed from the EPA’s “Remedial Action List”.

Investment in a new covered reservoir “is a significant additional measure to protect and upgrade the water quality in the reservoir”, it said in a statement.

The site will remain an active treated water storage area and, consequently, public access will not be permitted, it added. The existing Stillorgan site is one of the last remaining open service reservoirs of treated drinking water of its kind in Europe. Treated drinking water exposed to the environment presents an unacceptable contamination risk to public health as the water supply is vulnerable to being contaminated by wildlife, animal waste, airborne material and pollutants entering the supply from people accessing the water.

Project manager with Irish Water John Prendeville said: "Irish Water is pleased An Bord Pleanála has granted planning permission for the new covered reservoir . . . The locations of the decommissioned reservoirs will be maintained for future water services infrastructure to secure drinking water for the community. Irish Water needs to retain the entire site for this future development."

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times