Potential groundwater contamination from pit latrines in Ga-Maja and Reefentse

Abstract

Pit latrines are one of the most common methods of human excreta removal in low-income countries. Groundwater is a critical water resource in many peri-urban areas where there is no municipal water supply. Groundwater resources are commonly vulnerable to pollution from on-site sanitation practises, which may degrade their quality. Because groundwater is widely used for domestic purposes, maintaining groundwater quality is a vital livelihood intervention in rural areas. This study sought to assess the impacts of pit latrines on groundwater quality in Ga-Maja, Reefentse and Ga-Mothiba which was used as the reference site. For the purpose of this study, samples were collected from boreholes and a hand-dug well in the study areas. An assessment of microbial, chemical and physical qualities of groundwater in Ga-Maja, Ga-Mothiba and Reefentse was carried out to determine whether contamination of groundwater from the use of pit latrines could lead to potential human health risks. The samples were analysed for calcium (Ca), fluoride (F), iron (Fe), magnesium (Mg), nitrate nitrogen (NO3-N), phosphate (PO₄³⁻), sodium (Na), sulphate (SO4), total organic carbon (TOC), pH, total dissolved solids (TDS) and electrical conductivity (EC). These are some important parameters for assessing the groundwater quality for drinking purposes. The South African National Standards (SANS 241) and the Department of Water Affairs and Forestry (DWAF), now known as the Department of Water and Sanitation (DWS) South African Water Quality Guidelines (SAWQG) for domestic use were used to assess groundwater’s suitability for domestic and drinking purposes. This study used the Colilert™ technique to determine indicator organisms, and the agar diffusion method to determine antibiotic resistance in isolated pathogenic bacteria. Isolates were assayed against ten antibiotics using the Kirby Bauer disc diffusion technique. Identifying the sensitivity and resistance of specific pathogens to a variety of antimicrobial agents is necessary as it influences the choice of antibiotics for empiric management of infections and effective hospital infection control.

The results showed that most of the parameters were within the permissible range of DWAF guidelines for domestic water use and SANS 241 drinking water guidelines. Samples from Ga-Maja showed EC value of (76.7 mS/m), concentration of TDS (490.88 mg/L) and Ca (45 mg/L) above DWAF domestic water use guidelines. During the wet season, all samples had high total coliforms above DWAF domestic water use guidelines and SANS 241 drinking water guidelines. The presence of nitrates at high concentrations was another health concern present in Reefentse. A number of organisms that are potential pathogens were identified from the study areas. During the wet season, all isolates were resistant to amoxicillin-clavulanic acid. There was high resistance to many antibiotics particularly ampicillin (67%), ciprofloxacin (78%), erythromycin (78%), gentamicin (78%) and tetracycline (63%). During the dry season, all isolates displayed resistance to the macrolides (clarithromycin and erythromycin), amoxicillin-clavulanic acid, ciprofloxacin, and gentamicin. There

was high resistance to many antibiotics particularly ampicillin (77%), norfloxacin (85%) and tetracycline (85%). Undesirable properties of water quality caused by the presence of antibiotic-resistant bacteria can pose a negative impact on human health. The presence of total coliforms at high concentrations from all sites is a public health concern. The nitrate levels were high in Reefentse, making the groundwater unsuitable for human consumption. Water treatment and the use of alternative sources are possible solutions for improving the quality of water used for drinking and other household purposes.