WATER RESOURCE QUALITY: DEVELOPING A FRAMEWORK FOR THE MITIGATION OF GEOGENIC CONTAMINATION OF DRINKING WATER

The second half of the 20th century has seen a rapid growth in groundwater use due to the introduction of mechanised pumping and it is estimated that over half the world’s population relies on groundwater as a drinking water source. Although groundwater can supply safe drinking water largely free of the pathogens that contaminate surface waters, its quality can be affected by natural or geogenic contaminants leached from the aquifer’s rocks and sediments. Arsenic and fluoride pose the most serious health threat to an estimated 200 million people, or roughly 5% of those who use groundwater for drinking, worldwide.

At Eawag, the Water Resource Quality (WRQ) project consists of a group of 18 scientists working together to develop a conceptual framework for mitigation of geogenic contaminants in drinking water. The framework and associated practical tools are designed to support government agencies and NGOs in making regional assessments as well as providing practical guidelines on integration of technical, institutional and sociological aspects so that sustainable mitigation of contaminated drinking water tailored to local conditions can be achieved.

The first step in mitigating geogenic contamination in drinking water is the assessment of the extent of the problem and of potential alternative water sources. Here we present on-line tools for regional assessment, including open-source software applications which allow the user to visualise spatial data and dynamically model risk. Outputs can be visualised in Google Earth or exported to ArcGIS layers, spreadsheets or other formats.

Once it is established that drinking water contains unacceptable levels of geogenic contaminants, different mitigation options must be considered in terms of their technical viability, psycho-social acceptability, and harmonisation with existing institutional settings. We illustrate the integration of these three components through case studies of fluoride mitigation in Ethiopia and arsenic mitigation in Bangladesh. Outputs from both case studies are integrated in an interactive manual which can be used by development partners in countries facing geogenic contamination.