Assessing risk to groundwater from on-site sanitation : scientific review and case studies

Many people in developing countries rely upon untreated groundwater supplies for their drinking water. During the United Nations Water Decade of the 1980s considerable progress was made with the provision of safe drinking water and sanitation in both rural and urban areas. Even so, in many of these countries a substantial portion of the population still do not have access to an adequate water supply whilst access to sanitation facilities continues to lag behind that of water supply (WHO and UNICEF, 2000). It is recognised that further improvements in safe water and sanitation coverage will require both increased use of groundwater and greater utilisation of on-site sanitation systems. However there are concerns, that these two solutions may conflict. Under some hydrogeological conditions on-site sanitation systems may result in severe contamination of groundwater which could negate the anticipated health benefits.