Evaluation of groundwater quality in rural-areas of northern Malawi: Case of Zombwe Extension Planning Area in Mzimba

• We assessed water quality of 20 boreholes in Zombwe EPA, Mzimba, Malawi.
• We analysed physico-chemical parameters and compared with drinking water standards.
• Generally, results showed levels of groundwater pollution not significant.
• There is need for spatio-temporal variation assessment and microbiological analyses.

Many people in in the Sub-Saharan region rely on groundwater for drinking and other household uses. Despite this significance, information on the chemical composition of the water in the boreholes and emperical data on groundwater quality is limited in some rural areas of Malawi. This study was conducted to evaluate the physico-chemical quality of water from boreholes (n = 20) in Zombwe Extension Planning Area (EPA), Mzimba in Northern Malawi to ascertain their safety. Desktop studies and participatory approaches were employed to assess the socio–economic activities and water supply regime in the study areas. The water samples were analysed for pH, conductivity (EC), turbidity, water temperature, nitrate (NO3−), magnesium (Mg), calcium (Ca), zinc (Zn), fluoride (F−), and sulphate (SO42−). In-situ and laboratory analyses were carried out using portable meters and standard procedures. The results were compared with national (Malawi Bureau of Standards – MBS) and international standards (World Health Organization – WHO) for drinking water. The following ranges were obtained: pH (6.00–7.80), EC (437–3128 μS/cm), turbidity (0.10–5.80 NTU), water temperature (27.0–30.60 °C), NO3− (0.30–30.00 mg/L), F− (0.10–8.10 mg/L), Mg (31.00–91.00 mg/L), Ca (20.00–197.10 mg/L), SO42− (10.20–190 mg/L), Fe (0.10–3.60 mg/L) and Zn (0.00–5.10 mg/L). Generally, some parameters tested at several sites (>80%, n = 20) complied with both MBS and WHO limits. No significant differences (p > 0.05) was observed for most parameters (>65%, n = 11). Groundwater contamination was not significant in the area despite some parameters like F−, Ca and SO42− showing higher levels at other sites. Some sites registered very hard water (244.60–757.80 mg/L CaCO3) probably due to mineralization influenced by underground rock material. Further studies are needed to ascertain the groundwater quality of other parameters (like F−, and SO42−) which registered higher levels at some sites. Routine monitoring of the groundwater in the study area and entire Malawi is needed for spatio-temporal variation assessment and to ensure good public health.