State water company Uisce Éireann completed one of its biggest-ever repair projects to a key pipeline that is critical to Dublin’s supplies in not much more than 24 hours last August, according to the company.
Regulators could clear the utility to spend close to €14 billion over four years as it bids to rebuild the water supply system to cope with growing demand, including preparing it to take on new houses, and on upgrading ageing pipes around the State.
The pipe repaired in August connects the Uisce Éireann water treatment plant at Ballymore Eustace, Co Kildare, with a reservoir in Saggart, Co Dublin. It supplies one third of greater Dublin’s water, according to Mark O’Duffy, the project manager.
Uisce Éireann identified a series of structural weaknesses and large leaks that threatened “catastrophic” consequences had they not been repaired, he says.
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“If it had burst it would mean significant local damage and you would be talking about several days to fix it,” he says. That would have hit supplies to large numbers of customers across the capital.
In the event, Uisce Éireann had 28 hours to tackle the problem. But preparing for those few hours took nine months of planning. The utility identified the August bank holiday weekend as the most suitable time.
Many people are away so demand is particularly low. The company still had to limit supplies to 500 customers, which is “not bad out of 1.7 million”, O’Duffy says.
In advance of this, the company surveyed the pipes to identify leaks and other problems. Then staff had to work through every conceivable problem. “We had to go through every scenario we could think of. Everything was duplicated just in case something went wrong. Every last detail is planned down to the nth degree.”
And something always goes wrong with a project of this nature, O’Duffy says. In this case, a collision on the Naas Road delayed one of the crews, not an ideal scenario if you are already working on a tight deadline.
The first challenge was to empty the pipe itself. This required Uisce Éireann to design and build a temporary lagoon to hold about 14 million litres of water to allow them carry out the work in the first place.
The job itself consisted of two key elements: internal and external repairs to the pipeline. Specialist crews carry out the internal work. The pipe is concrete and 1.6m in diameter.
Workers physically enter it and walk along its length, finding known leaks and repairing them with metal seals. “This is very dangerous work,” O’Duffy says, adding that it has to be done in difficult and cramped conditions.
The second element involved removing sections of concrete pipe totalling 35m, about the size of a Luas tram, repairing and then replacing them. This was complex work that had to be done “against the clock” and completed before supplies to the capital began to suffer.
Any longer than 28 hours threatened wider disruption. Uisce Éireann shut down the system at 10pm on the Friday of the bank holiday weekend and restored the system 26½ hours later, early on Sunday morning.
O’Duffy says that the State company got “huge buy-in” from local landowners, whose co-operation was needed to allow it get access to the pipe. That also involved restoring their property after the task was completed.
It also had to work with agencies such as the fire service and State-owned airport operator DAA to ensure it could complete repairs with minimum impact on their operations.
In all, about 1,000 people worked on the project through the nine-month planning stage and during the critical hours in which the company completed the task.
This is unlikely to be the last such project that Uisce Éireann undertakes. In fact, Duffy says that it is already working on further repairs to the same line next year.
Work on the Ballymore-Saggart line was one of many projects that the State-owned utility completed during 2025.
Along with meeting demand for new connections, needed to supply new homes, it has to constantly monitor the existing infrastructure to find and repair leaks.
Water pipes in the Republic can be as old as 150 years or more, according to O’Duffy. Allied to this, the system has suffered years of underinvestment, even as demand for water grew rapidly, he says.
The Commission for Regulation of Utilities (CRU) is consulting on a proposal to allow Uisce Éireann spend €13.8 billion up to 2029 on new water treatment and waste plants, among other facilities.
The figure is 50 per cent more than what the company invested over the five years to 2024. If it gets the final go-ahead, the utility will spend €8.56 billion on new infrastructure and €5 billion on its operations.
The commission will end consultations on the plan on January 27th.
