Groundwater quality and human health-risk assessment in health-care facilities around Vhembe District, Limpopo, South Africa

Abstract

Water quality has been associated with health outcomes globally. This research assessed the physicochemical and microbial quality of groundwater in health care facilities around Vhembe District, Limpopo Province, South Africa. For this study, nineteen sampling locations were chosen from among the many local municipalities in the Vhembe District, and sampling was conducted throughout both the rainy and dry seasons. During the various seasons, physicochemical characteristics like turbidity, salinity, pH, EC, and TDS varied as follows: (35.46-1780 μS/cm (dry), 126.38-1468 μS/cm (wet), 25.5-1267 mg/L (dry), 67.5-1195 mg/L (wet), 7-8.5 (dry), 7-9 (wet), 0-4.5 NTU (dry), 0-6 NTU (wet), and 42.31-899 ppm (dry), 37.28-706.5 ppm (wet) respectively with some samples exceeding the recommended limit standard as per SANS guideline. Total coliform levels ranged between 2-90 cfu/100 mL in the dry season and 1-128 cfu/100 mL in the wet season. E. coli varied between 0-13 cfu/100 mL) in the dry and 0-39 cfu/100mL in the wet, respectively. Major anions such as SO4, NO2, PO4, recorded levels within the recommended limit of the South African National Standards (SANS), however, anions such as F, Cl, and NO3 in some of the samples did not comply. Major cations (Na, Mg, K, and Ca) did not comply for some samples except for K which complied in all samples. The following metals - Al, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Hg, Pb, and U - were within the recommended limit except for Fe which was above the recommended limit as per SANS 241. According to the water quality index (WQI), during the wet season, 16.66% of the water was extremely poor, 38.88% was poor and 44.44% was good. 16.66% was poor, 72.22% was decent, and 11.11% were excellent during the dry season. The Piper Diagram revealed three hydro-chemical facies for both seasons. Calcium chloride water type (72.22 % in wet, and 83.33 % in dry season), mixed water type (5.5 %) and sodium chloride water type (22.22 % in wet and 11.11% in dry season). The Durov Plot revealed that most samples were in the ion exchange zone and very few were in the mixing zone or dissolution. The study area's groundwater Gibbs diagram, for both seasons demonstrated that evaporation mostly regulated the hydrogeochemical processes. The average dosage of E. coli ranged from 0 – 3.16 and 0 - 0.24 for wet and dry respectively, therefore, chances of getting infection daily, was in the range of 0 – 7.6 % for wet and 0 – 6.7 % in the dry season. The probability of getting infection annually ranged as from 0 – 100%. Water from health-care facilities around Vhembe District should be treated before consumption.