Classification and quality of groundwater supplies in the Lower Shire Valley, Malawi – Part 2 : classification of borehole water supplies in Chikhwawa, Malawi

摘要

This paper compares data gathered from a study of the chemical and bacteriological quality of drinking-water from 28 rural borehole supplies in Chikhwawa, Malawi, with a tiered classification scheme (Class 0 being ideal through to Class III being unsuitable for drinking without prior treatment) developed by investigators from the Institute for Water Quality Studies, Department of Water Affairs and Forestry, South Africa. In general, the majority of borehole water supplies were classified as Class 0 or Class I supplies based upon the chemical analysis and bacteriological examination. However the classification of a borehole water supply was variable and depended upon the parameter, date of sampling and whether or not it was based on the mean or individual concentration. A number of boreholes were classified as II or III as they contained elevated levels of fluoride and nitrate suggesting that consumption over short or prolonged periods of time may lead to adverse or serious health effects, such as skeletal fluorosis in adults and methaemoglobinaemia in infants. Research is required to develop practicable, affordable and sustainable methods to enable villagers to treat Class II/III water supplies and improve the quality of their drinking-water to a class suitable for human consumption.