How groundwater is formed, what it consists of and how water levels and quality are monitored in Northern Ireland.

What is groundwater?

Groundwater can be found beneath most parts of Northern Ireland and forms an integral part of its water cycle. It is contained within geological deposits beneath the ground with the water stored in pore spaces between mineral grains and/or within fractures and cracks in the rock itself.

Groundwater is an important natural resource that supports river flows as well as ecological diversity in rivers, lakes and wetlands. It is also available for use for water supply by abstraction from boreholes, wells and springs.

Groundwater quality

The natural chemistry of groundwater is influenced by a variety of factors such as the type of rocks it flows through, or its proximity to coastal salt waters.

Generally, groundwater in its natural state is of good quality as the soils and rocks it moves through act as filters. However, groundwater quality can be affected by a wide variety of land use such as the over-application of nitrates and pesticides, leaks from hydrocarbon storage tanks, contaminated land drainage, or poorly sited, or constructed, septic tanks.

Pollutants can be either chemical or microbiological and the deterioration of groundwater quality can impact on those rivers and lakes into which the groundwater discharges.


The Groundwater Directive (2006/118/EC) (GWDD) is a ‘daughter’ Directive of the Water Framework Directive (2000/60/EC) (WFD) and its purpose is to clarify certain objectives for groundwater quality in WFD. The Directive includes criteria for the assessment of good chemical status and for identifying and reversing upward trends in pollution. It also details measures to prevent or limit pollutants.

The Groundwater Regulations (Northern Ireland) 2009 transpose the GWDD and have subsequently been amended by the Groundwater (Amendment) Regulations (Northern Ireland) 2009,  the Groundwater (Amendment) Regulations (Northern Ireland) 2011 (which contain an amendment in respect of the Carbon Capture and Storage Directive 2009/31/EC) and the Groundwater (Amendment) Regulations (Northern Ireland) 2014


Groundwater quality is routinely sampled and tested using a network of boreholes and springs across Northern Ireland. Data collected is used to assess compliance with European legislation such as the Nitrates (91/676/EEC) and Groundwater (2006/118/EC) Directives.

Guidance on groundwater management and protection:-

Hazardous Substances Standards – Interim Regulatory Position

This Interim Regulatory Position Statement clarifies how the Northern Ireland Environment Agency (NIEA) regulates the input of hazardous substances into groundwater and the standards to be achieved through extant licences/ permits.

This interim statement will remain in place until an update of this regulatory position is published in spring 2017. This update will follow a consultation exercise on the implementation of the UK Technical framework for monitoring, assessing and controlling risks to groundwater.


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