Qualitative risk assessment of self-supply hand-dug wells in Abeokuta, Nigeria: a water safety plan approach

01.01.2013
The development of water safety plans for self-supply systems should be based on a thorough understanding of contamination events, identified risk factors, and source management practices. This paper presents an experience from a self-supply hand-dug wells assessment in Abeokuta, Nigeria, which illustrates the water safety plans process. A total of 99 hand-dug wells were assessed. Particular reference was made to the use of qualitative risk assessments of identified hazardous events for water safety plans for these types of systems in developing countries. Sixteen hazardous events are identified with 21 causes found to be responsible for the events. Proximity of hand-dug wells to sources of contaminations, coupled with the problems of construction, operation, and hygiene are highlighted as four major water safety threats. Five major risk factors are further associated with self-supply wells in the location. The paper noted the urgent interventions needed for the safety of source, water, and public health and discusses the need to provide multiple safe barriers against source water contamination. It concludes that qualitative risk assessment based on well-defined sanitary survey and risk characterization processes can provide a basic tool for water safety interventions; that is, interventions to household-level systems where sophisticated hazard and risk analytical approaches may not be feasible.