Groundwater quality assessment guidelines published

On Monday June 3, 2024, Friends of Groundwater, a group working within the World Water Quality Alliance announced the publication of new guidelines for groundwater water quality assessment.

A first version had been published in 2022, subsequently supplemented and improved, incorporating practical experience in Uganda, Chile, Sweden and South Korea. These different countries enabled the testing of the guidelines in a variety of different situations, the variables being available data and groundwater quality, which can vary enormously from one country to another depending on local hydrogeology and anthropogenic factors.

Friends of Groundwater is an international group of groundwater experts involved in the activities of the World Water Quality Alliance (WWQA), an initiative of the United Nations Environment Programme. The work in preparation for the publication was carried out in collaboration with the International Groundwater Resources Assessment Centre (IGRAC), a research center based in the Netherlands since 2003.

The primary objective of the guidelines is to support the process of global groundwater quality assessment, which falls within the broader goals of the WWQA. The guidelines provide a structured methodology such that countries can make the most effective use of available groundwater quality data in the poursuit of national and international water quality goals.

The guidelines are an important contribution to SDG 6 water quality indicator 6.3.2, on which  states report on the proportion of water bodies (groundwater, rivers, and lakes) within their territories which have ‘good’ ambient water quality.  To support this process, indicator 6.3.2  needed to be supplemented by introducing additional water quality parameters and attempting to make up for delays in groundwater data collection.

The World Water Quality Alliance reported in its June 2024 newsletter that in the previous global reporting cycles on SDG 6 in 2017 and 2020, groundwater was the least reported water body type. This highlighted the need to focus more on monitoring and reporting of this vital resource and to redouble efforts in this regard. This work is described as complex, due to "the hidden nature of groundwater, its tridimenssional distribution and long residence time" (...), as well as "the absence of standard guidelines for groundwater quality assessment", with several tools and approaches coexisting.

The latest version of the guidelines aims to encourage and promote the monitoring and assessment of groundwater quality and support the production of information that is important for decision making, based on existing monitoring data. In addiiton, the guindleines have incorporated the target values of the World Health Organisation’s drinking water guidelines.

In principle, the assessment if based on the calculation of a groundwater quality index, followed by a classification of the quality of the resource on the basis of its potential risk to human health, which can also be transposed, by adapting certain parameters and target values, to ecosystem health.

The guidelines comprise 4 stages, i,e, the assessment of existing groundwater monitoring networks in terms of their representativeness, followed by data collection and processing, the selection of parameters to be used for assessment, and finally the calculation of the groundwater quality index and classification of groundwater quality.