Summary
- Uisce Éireann data indicates roughly 514m litres of data-centre water use from May through July.
- July consumption exceeded 200m litres during a period of national water restrictions.
- Cooling design and operating conditions can make water demand highly seasonal, complicating annual comparisons.
Irish data centres connected to the public water network consumed around 514m litres between May and July, according to figures supplied by Uisce Éireann, as hotter and drier weather increased pressure on national water supplies.
The reported total compares with roughly 276m litres during the first four months of 2026. July alone accounted for more than 200m litres, making the seasonal increase significant even before accounting for differences in the number and utilisation of facilities.
The figures cover 57 data centres connected to public water supplies and were obtained following questions from Labour TD Ciarán Ahern. They indicate daily demand moving from roughly 1m-3m litres in the opening months of the year to around 4m-6m litres during May, June, and July.
The increase coincided with unusually dry conditions and national restrictions on domestic water use. Commercial users, including data centres, were not subject to the household hosepipe ban, but the overlap has intensified scrutiny of how large industrial water loads are managed during periods of system stress.
Data-centre water consumption can vary sharply according to cooling design and weather. Facilities using evaporative systems may consume more water when outside temperatures rise because evaporation is used to reject heat more efficiently than purely mechanical cooling under suitable conditions. Sites relying predominantly on dry or closed-loop systems can have much lower direct water consumption but may require more electricity in some operating states.
That makes a single annual water figure difficult to interpret without the underlying cooling configuration, IT load, climate data, and measurement boundary. Water usage effectiveness, normally expressed as litres per kilowatt-hour of IT energy, can provide a more useful comparison than an absolute volume, but even WUE requires site and weather context.
DataCentral has previously examined how European data-centre water infrastructure is becoming a more prominent investment and regulatory issue as higher-density compute increases the amount of heat that facilities must remove. Ireland adds another constraint: a large concentration of data centres sits alongside an electricity system already managing substantial digital-infrastructure demand, while water availability can become politically sensitive during dry summers.
The latest figures do not show that every Irish data centre increased consumption by the same amount. Differences between individual facilities can be large, particularly where some use public water primarily for domestic and ancillary purposes while others depend more heavily on evaporative heat rejection.
They do, however, demonstrate why operators and policymakers increasingly need seasonal rather than annual reporting. A facility whose annual water demand appears modest may still impose its highest requirement at exactly the point when a utility is managing drought conditions and peak demand elsewhere on the network.
As Ireland develops further rules around data-centre infrastructure, the question is likely to move beyond total litres consumed towards where that water comes from, which cooling systems require it, how use changes during hot weather, and what operational flexibility facilities can offer when public supplies are constrained.
