Minister for Housing, Local Government and Heritage James Browne TD has updated Cabinet as Uisce Éireann signs off on the Detailed Business Case for the Greater Dublin Drainage (GDD) scheme, valued at between €1.9 billion and €2.3 billion. Pre-qualification tender documents are to issue this week.

Uisce Éireann's approval marks a major milestone for one of the largest wastewater infrastructure projects in the State. The new treatment plant for the Greater Dublin Area is intended to provide additional treatment and network capacity to support long-term sustainable growth, unlock new housing, and ensure continued compliance with European law.

Minister Browne emphasised: "The Greater Dublin Drainage project is critical to facilitate growth in the Greater Dublin Area and to help us in achieving the aims of Delivering Homes, Building Communities, our new housing action plan.

"This project is progressing well, with Judicial Review proceedings resolved late last year and the project having now secured planning permission. Uisce Éireann's Board have now approved the Detailed Business Case for the project, a crucial milestone, and Uisce Éireann is taking all possible measures to accelerate the delivery of this project. Given the strategic importance of this infrastructure, my department will do everything necessary to support its delivery and bring it to the next stage of project delivery."

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Uisce Éireann will now move to procurement, with pre-qualification documents being released this week.

The GDD sits alongside Uisce Éireann's Water Supply Project for the Eastern and Midlands regions, reflecting significant Government investment in strategic water infrastructure to support economic development and housing delivery across Dublin, the east and the midlands.

The GDD will comprise a new 500,000 Population Equivalent wastewater treatment plant at Clonshaugh, a 14km orbital sewer linking Blanchardstown to the plant, and an 11km outfall pipeline discharging 6km off the north County Dublin coast.

Located on the southern fringes of Fingal just outside the M50, the project will serve the north-west quadrant of the existing Ringsend catchment. Diverting flows to the new plant will reduce the load on Ringsend, freeing up critical network capacity for planned growth elsewhere in that catchment and enabling future development in the GDD catchment, including Leixlip, Blanchardstown, Clonee, Dunboyne, Ashbourne and Ratoath.

As an inflight project, the GDD did not progress through Approval Gate 1 (Preliminary Business Case) under the Infrastructure Guidelines. With the Detailed Business Case now approved (AG2), the Final Business Case is scheduled to come before Government in mid–2028 to proceed at Approval Gate 3.