Quality of groundwater from shallow wells of selected villages in Blantyre District, Malawi

摘要

Access to adequate and safe drinking water still remains a challenge in developing countries. Some people especially in the rural areas use untreated surface and groundwater. An assessment of groundwater quality from shallow wells was carried out in nine villages in Blantyre district of Malawi. Water samples from nine randomly selected shallow wells (7 covered or protected and 2 open) were analysed for biological (total and faecal coliforms), chemical (hardness, nitrate, nitrite, sulphate, ammonia. pH, electrical conductivity and arsenic) and physical (total dissolved solids and turbidity) parameters of water using a portable water testing kit (Paqualab 50). Sampling was carried out four times during the year, i.e. twice in the dry season (August and October) and twice in the wet season (February and April) to find out if the quality of water changes with season. Results indicate that drinking water from shallow wells is heavily polluted by both total and faecal coliforms. The pollution level was higher in the wet season compared to the dry season. All the samples tested in the wet season did not meet the guideline value of 50 total coliforms (colony forming units) per 100ml of the sample water (50cfu/100ml) set by the Malawi Ministry of Water Development (MoWD) for untreated water for drinking purposes (e.g. groundwater), while 22% of the samples met the guideline during the dry season. The difference in the contamination level between the dry and wet season was not significant for total coliforms (p=0.13>0.05). All chemical (hardness, nitrate, nitrite, sulphate, ammonia, pH. electrical conductivity and arsenic) and physical (total dissolved solids and turbidity) parameters tested except for turbidity were within the guideline values set by MoWD for untreated water. About 11% of the wells tested failed to meet the turbidity guideline value for the Ministry of Water Development of 25 NTU while about 22% failed to meet the World Health Organisation (WHO) and Malawi Bureau of Standards (MBS) for treated water of 5 NTU in both the dry and wet season. There is need to carry out a further analysis of quality of water from shallow wells in Blantyre and other districts.