Guidelines for assessing the risk to groundwater from on-site sanitation

This manual provides guidance on how to assess the risk of contamination of groundwater from on-site sanitation systems when planning low-cost water supply and sanitation schemes. The first part of the manual discusses the role of water and sanitation in reducing infectious diseases caused by pathogenic micro-organisms, including the role of indicator bacteria. The advantages and of different sanitation systems are also presented. This is followed by a discussion on aquifer contamination pathways and aquifer vulnerability, microbiological (fecal) contaminant attenuation and risk categories. The second part of the manual provides the actual guidelines. It starts with three first-step risk assessments: microbiological contamination via aquifer pathways, nitrate contamination, and microbiological contamination via well constructions. The last set of guidelines are on water quality monitoring and answer the questions: why, how, when and where to monitor, and how to analyse and interpret data. Annexes include worked examples and sanitary inspection forms.