Sewers: inside or outside an agglomeration
The EPA licenses each public wastewater system and maps the area it serves, called an agglomeration. There are over a thousand, from cities to small villages.
- Inside one: a connection to the public sewer is at least plausible, subject to a sewer being near enough and Uisce Éireann agreeing.
- Outside every one: plan for your own wastewater treatment system (septic tank or packaged plant), with a site suitability assessment.
Treatment plant capacity
Each agglomeration's plant has a design capacity and a current load, both in population equivalent (PE), a measure of how much sewage it treats. Design capacity minus load gives a rough idea of headroom. A plant that's already over capacity, or that's failing the EU Urban Waste Water Treatment Directive, can hold up new connections and new development in that town.
Drinking water
- The EPA's Remedial Action List names public water supplies with known problems being fixed. A supply on the list near a site doesn't necessarily serve it.
- Mains, group scheme or well? Where mains water reaches isn't published. The best stand-in is the 2022 Census, which records for each Small Area (about 80 to 120 homes) how many households are on the public mains, a group water scheme, or their own well.
Septic tank inspection risk zones
For sites outside a sewer area, the EPA's National Inspection Plan targets inspections of septic tanks and treatment systems at higher-risk areas, for example near drinking water sources or sensitive rivers.
What it can't tell you
- Whether there's a water main or sewer at the site boundary, or whether Uisce Éireann will allow a connection. Ask for a pre-connection enquiry.
- Census Small Areas in the countryside can be very large, so the split is a general picture of the area.
Related
- Groundwater vulnerability and soil, for septic tank suitability
Sources
- EPA: Urban Waste Water agglomerations, treatment plants, plants failing the UWWT Directive, drinking water Remedial Action List, domestic wastewater risk zones, CC BY 4.0
- Central Statistics Office: Census 2022, households by water supply (Small Areas), CC BY 4.0
Last reviewed 2026-10-02.