This data delineates areas with an indication of increased potential risk to groundwater supplies from DWWTS. This is based on interpreting mapped geological information to determine areas where there is increased likelihood of inadequate treatment of the waste water by the percolation area. It was created by combining areas from two data layers: areas with a high susceptibility of groundwater to percolation of MRP and Microbial pathogens from DWWTS and areas with a very high or high likelihood of inadequate percolation. This dataset was developed for the National Inspection Plan 2018 – 2021. The aim of the Plan is to protect water and human health from risks posed by domestic waste water treatment systems. For further information see the National Inspection Plan 2018 – 2021 report on www.epa.ie

This data layer was integrated with surface waterbody characterisation data from the Water Framework Directive (WFD) characterisation in a GIS to produce a single, harmonised layer of 10 risk zones within the Republic of Ireland.