Project Overview

The Stillorgan Reservoir Upgrade is a priority project for Irish Water. This project is necessary to ensure a secure and sustainable supply of water to over 200,000 people in south Dublin. After almost 150 years serving the community, the Stillorgan Reservoir will be modernised to adequately meet current requirements and the needs of future generations.

Irish Water has already invested €3.4 million in a new system to improve the disinfection of drinking water stored in the Stillorgan Reservoir.  Following this investment, the Environmental Protection Agency (EPA) removed the Stillorgan Reservoir from the Remedial Action List (RAL).  The long term solution to upgrade the reservoir is now being progressed. 

Project Background

The reservoir was originally constructed as part of the Vartry Water Supply Scheme which also includes two impounding reservoirs at Roundwood, County Wicklow, a water treatment plant, a four kilometre long tunnel under Callowhill and 40 kilometres of trunk mains to deliver water to the Stillorgan Reservoir. The reservoir has also been supplied from the water treatment plant at Ballymore Eustace in County Kildare since the 1950’s.

The Vartry Scheme commenced construction in the 1860s and was an amazing feat of engineering at the time. This work was particularly important as it helped to greatly improve living conditions and public health in Dublin city. It improved sanitation and helped reduce outbreaks of cholera, typhus and other diseases associated with contaminated water.

Stillorgan Reservoir

It is a testament to the success of the project that the reservoir still provides drinking water to around 15% of the Greater Dublin Area.

Irish Water is the national water utility responsible for providing and developing water services throughout Ireland. Incorporated in July 2013, as a semi-state company under the Water Services Act 2013, Irish Water brings the water and wastewater services of 31 Local Authorities together under one national service provider. Dublin City Council continues to have responsibility for the day-to-day operation of the scheme.

What will this project involve?

The Stillorgan Reservoir Upgrade Project will include:

  • Draining the Gray Reservoir and constructing a new covered reservoir and control building.
  • Once the new covered reservoir is operational the Upper and Lower Reservoirs will be drained and decommissioned. The decommissioned areas will be reserved for future water services facilities.
  • Landscaping the decommissioned reservoir areas in accordance with a landscape masterplan.
  • Pipeline modifications within the reservoir site.

Subject to planning permission being granted, it is anticipated that construction will commence in 2018 and is expected to last approximately two years. Once the new covered storage is fully commissioned, the existing Upper and Lower Reservoirs will be decommissioned. It is expected that this will take approximately twelve months. View our Project Roadmap for further details. 

News and Updates

Irish Water submitted a planning application for the upgrade project to Dún Laoghaire-Rathdown County Council in November 2016.

The application was supported by an Environmental Impact Statement. The Council requested further information on the project proposals on 20 January 2017 and a response was submitted to the Council on 10 April 2017.

To view the planning application on the Dún Laoghaire-Rathdown County Council online planning website, please click on the following link: Planning application Details.

Irish Water conducted a non-statutory public consultation for six weeks from Wednesday, 3 August to Wednesday, 14 September 2016.  The submissions received were considered and, where appropriate, informed the development of the Environmental Impact Statement and the project design.

Irish Water prepared a report following this consultation period outlining the detail of the submissions and how public feedback was considered throughout. For more information, please visit our Consultation Report.

Planning permission for the reservoir works was granted, subject to sixteen planning conditions, by Dún Laoghaire-Rathdown County Council on the 1 June 2017.  Irish Water lodged an appeal to An Bord Pleanála seeking the removal of one of the conditions which is to provide publicly accessible open space within the site. In December 2017, An Bord Pleanála approved the planning application to ensure Irish Water will retain the entire site for this future development.

The current upgrade project is planned for completion in 2021. Planning for additional water storage at the site will commence in the early 2020s with construction of additional storage likely to follow in the late 2020s to ensure that evolving needs are met. 

The site is an active water supply site and contains high pressure pipes and valves, and the view of Irish Water is that the use of the site for publicly accessible open space is not feasible.

Irish Water also responded to feedback from local residents as part of its consultation in advance of submission of a planning application for this project. Residents expressed concerns in relation to security in the area, if the site were to be accessible by the general public, and Irish Water noted that the clear intention in its application for planning was to maintain this site solely for strategic water infrastructure.

Please visit our Public Participation page for more information.

Contact Us

For further information about the Stillorgan Reservoir Upgrade Project please contact the project team as follows:

  • Telephone: 1890 815661
  • Email:
  • Postal enquiries: FAO Stillorgan Reservoir Project, Colvill House, 24-26 Talbot Street, Dublin 1.

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