Assessment of the chemical quality of groundwater for drinking in Dedza District, Malawi

Abstract

A lot of emphasis has been placed on the safety of drinking water from biological contamination with little consideration on the chemical quality although there are well known health risks associated with the consumption of groundwater with high levels of chemical pollutants. An assessment of the chemical quality of groundwater was done in Kachindamoto Traditional Authority area, in Dedza district of Malawi. The area was chosen because of the reported occurrence of salty water in some places. The main purpose of the study was to determine the chemical quality of groundwater and to compare it to the Malawi Bureau of Standards (MBS) and the Ministry of Irrigation and Water Development (MoIWD) Standards and identify critical areas and possible interventions. Samples were collected from 48 groundwater points and analysed for selected water quality parameters. Field tests were carried out for pH, conductivity and temperature while TDS, carbonate, bicarbonate, chloride, sulphates, nitrate, fluoride, sodium, potassium, calcium, magnesium, iron, manganese, total hardness, total alkalinity and silica were analysed in a laboratory. It was found out that most parameters (75%) satisfied the MBS and MoIWD standards. Most communities reported that the groundwater quality was acceptable for drinking although there were more respondents who were of the view that the water was unacceptable for bathing and laundry. It was also established that the levels of most parameters increased with proximity to the lake. Indications of dental fluorosis were observed in adults in areas around 30% of the water points visited although the levels of fluoride found in the study were below the WHO guidelines, MBS and MoIWD limits. No observations or reports of other negative health implications of the other parameter studied were found. It was concluded that the water quality is generally of acceptable quality according to WHO guidelines, MBS and MoIWD standards. It is recommended that the depth of the water point, geological material and distance from the lake should be taken into consideration in future projects notwithstanding the optimum depth for minimum yield. Further studies on the long-term effect of exposure to certain parameters such as fluoride, nitrates and iron should be carried ou