New Stillorgan Reservoir brings big improvement to Dublin’s water supply

30 May 2022

The opening of a new state-of-the-art covered reservoir in Stillorgan means that over 200,000 Dubliners will now enjoy a much safer and more secure water supply, according to Minister for Housing, Local Government and Heritage Darragh O’Brien.

The Minister was speaking at the official opening today of the new covered reservoir, which will supply water to homes and businesses across South Dublin. The new covered reservoir, which can store over 160 million litres of treated drinking water, replaces three open reservoirs that were no longer fit for purpose as they were uncovered and presented a risk of contamination by birds, animals or human activities.

This project represents an investment of over €50 million by Irish Water, which will bring big benefits in terms of security of supply and resilience. It is the latest in a number of major upgrades of water supplies in the Greater Dublin Area designed to future-proof the supply to cater for increasing demand, population growth and the challenges that are likely to be presented by climate change.

Officially opening the new reservoir this morning, Minister O’Brien described it as a “critical element in the ongoing modernisation of the water supply for the Greater Dublin Area”. 

Water has been supplied to generations of Dubliners from this site for over 150 years. The construction of the Vartry scheme, of which the original Stillorgan reservoirs were part, was not only a major feat of engineering for its time but it also represented a visionary plan to bring clean, safe drinking water to the people of Dublin. The development of this new reservoir is a continuation of that vision and commitment to securing the water needs of the city and its people. This is critical, not only to the health and wellbeing of the population, but also to the development of the city, enabling us to meet our commitments under Housing for All, to create more businesses and attract more investment. This represents a huge leap forward in the provision of a more secure and resilient water supply for Dublin. Congratulations to Irish Water and all their partners for delivering this landmark project.

Niall Gleeson, Irish Water chief executive, added: “Providing safe, secure drinking water supplies for all our customers is a top priority for Irish Water. We are committed to building a world class public water infrastructure, carrying on the legacy of the committed Local Authorities that have developed and operated these sites for generations, while applying cutting-edge technology and expertise in the development of solutions for the future. We all recognise the need to improve our ageing water infrastructure and the completion of this project is another important step along the road to building a secure and sustainable water supply for the people of Dublin for generations to come.

We would like to thank the local community for their patience and support as we carried out this essential work, as well as our delivery partners in Dublin City Council, Nicholas O’Dwyer Ltd and Murphy’s Ireland.

Cathaoirleach of Dun Laoghaire-Rathdown County Council, Cllr. Lettie McCarthy, said: “This is great news for the people of South Dublin who are supplied with water from this site in Stillorgan. We will all benefit from the successful completion of this new reservoir and the wider investment by Irish Water in improving the water supply in the Greater Dublin Area. This is a great example of collaboration between Irish Water, Dublin City Council, their Local Authority partners, and everyone involved in the delivery of this project. I am delighted to be here on what is an historic day for Stillorgan and all of South Dublin.” 

The original Stillorgan Reservoir site comprised three open reservoirs and was one of the last remaining uncovered treated water reservoirs in Europe, where treated drinking water was left exposed to the elements, with consequent risk of contamination. The construction of the new covered reservoir will eliminate that risk and enable better management of the supply of water to customers. Construction work began on the upgrade project in 2018 with the draining down of the Gray Reservoir, which had not been fully drained since it was built in the late 1800’s. The new covered reservoir was then constructed within the footprint of the Gray Reservoir. 

The new reservoir is a key component of Dublin’s strategic water infrastructure, which links the supply from five major water treatment plants through an integrated network of trunk mains and reservoirs. It is supplied with drinking water from water treatment plants at Vartry in County Wicklow and Ballymore Eustace in County Kildare. The completion of the reservoir marks the culmination of a total investment of €150 million in the upgrade of the Vartry Water Supply Scheme, which also delivered the replacement of the old Vartry to Callowhill tunnel in 2018 and the construction of the new Vartry Water Treatment Plant which was completed in 2021. The reservoir and associated infrastructure will have the capacity to support future water demand through 2031 and beyond.