Catchment News

Significant Pressures: Domestic Waste Water

Domestic wastewater treatment systems (DWWTSs) are used to treat sewage, in the case where a house or premises is not connected to the main sewer. There are nearly half a million DWWTSs within Ireland, and the majority of these are septic tanks which serve single residential houses. They also include a smaller number of treatment systems that are designed for up to 500 people, generally found in businesses, leisure centres and hotels. Developer Provided Infrastructure (DPI) in housing estates which have not been taken in charge by the public authorities and do not have their water services connected to the public network managed by Uisce Éireann, are also included in this category.

These facilities can cause pollution issues due to their discharges where systems are sub-standard and/or are poorly maintained. Discharges from DWWTSs have been identified as the sixth most prevalent significant pressure in Ireland, impacting approximately 9% of all waterbodies ‘At risk’ of not achieving their environmental objective under the Water Framework Directive. This is based on the most recent characterisation assessment using data up to 2021.

In total, there are 148 water bodies that have a significant impact from domestic wastewater discharge. These are broken down as follows:

  • 78% from single house discharges;
  • 20% from communal discharges and;
  • Approximately 2% from unauthorised discharges that should be covered under Section 4 licences.

Of the 148 waterbodies with DWWTS discharge as a significant pressure, based on available data, discharges from DPI has been identified as causing impacts in approximately 18 waterbodies.

Impacts of discharges from DWWTS on Water Quality

Who is involved?

Quite simply, everyone in Ireland has a role to play. This can be from something as simple as making sure you don’t pollute your local stream, or a local community working together to establish a Rivers Trust to enhance the rivers and lakes in their area, to a Government Department or Agency helping a Minister implement a new policy to help protect and enhance all our water bodies.

This website has been developed and is maintained by the Environmental Protection Agency, and is a collaboration between the Department of Housing, Planning and Local Government, the Environmental Protection Agency, and the Local Authority Waters Programme.


Local Authority Waters Programme

The Local Authority Waters Programme coordinates the efforts of local authorities and other public bodies in the implementation of the River Basin Management Plan, and supports local community and stakeholder involvement in managing our natural waters, for everyone’s benefit.


Environmental Protection Agency

The EPA is responsible for coordinating the monitoring, assessment and reporting on the status of our 4,842 water bodies, looking at trends and changes, determining which waterbodies are at risk and what could be causing this, and drafting environmental objectives for each.


Department of Housing, Local Government and Heritage

The Department is responsible for making sure that the right policies, regulations and resources are in place to implement the Water Framework Directive, and developing a River Basin Management Plan and Programme of Measures to protect and restore our waters.