Identification of fecal contamination sources of groundwater in rural areas of Vhembe District Municipality, Limpopo Province, South Africa

Effluents from septic systems and impact on groundwater contamination: a systematic review

Globally, 2.2 billion people rely on groundwater for their water supply, and 2.8 billion use onsite sanitation systems for their sanitation needs. Groundwater contamination from septic systems is a critical public health concern, linked with diseases related to water sanitation and hygiene. Despite the severe impacts of septic systems on groundwater quality, comprehensive global studies remain limited. This study conducted a systematic review of articles published between 2012 and 2023 on topics related to septic systems and groundwater contamination, and 82 peer-reviewed articles met the inclusion criteria. The review identified key contaminants, including E.coli, nitrate, Enterococcus spp., total coliform, ammonium, phosphate, chlorides, and pharmaceuticals. Research on microbial indicators is more prevalent in Africa, while research on nutrients is common in North America. Research on organic contaminants including polyfluoroalkyl substances (PFAS), pharmaceuticals, and personal care products (PCPPs) is limited, particularly in low-and middle-income countries. Critical factors contributing to groundwater contamination include soil, hydrogeological conditions, climate, septic system maintenance and functioning, and septic density. The goal of this study was to comprehensively assess the extent of groundwater contamination resulting from septic system effluents by identifying the major contaminants typically found in affected groundwater sources and exploring the factors contributing to contamination. Identifying the major contaminants and factors related to groundwater contamination from septic systems is crucial for developing effective management strategies to protect groundwater sources.

Tracking enteric pathogen contamination from on-site sanitation facilities to groundwater in selected rural areas of Vhembe District Municipality, Limpopo Province, South Africa

Groundwater is valued as a source of potable water, although it is vulnerable to environmental pollution. The aim of this study was to track enteric pathogen contamination from on-site sanitation (OSS) facilities to 70 household boreholes used by four villages of the Vhembe District Municipality. Two objectives were pursued: to measure the lateral distance between the borehole and the sanitation facilities in household yards, and to track the enteric pathogens. The borehole abstraction point and OSS system distance were determined using a steel measuring tape. Real-time PCR was used to track Shigella flexneri, Salmonella typhimurium, Campylobacter jejuni, and enterotoxigenic Escherichia coli (ETEC) from Wastewater (WW) from domestic septic tank and sludge from pit latrines to boreholes. Escherichia coli was used as an indicator of faecal contamination. Results showed that 25% of households kept a distance of ≥50 m between the OSS facilities and the boreholes. In total, 87.5% of household boreholes in the rainy season and 72.5% in the dry season were contaminated with E. coli and pathogenic bacteria: Shigella flexneri, Salmonella typhimurium, and ETEC. The concentrations of the pathogens ranged from 2.03 to 2.12 LogEGC/100 mL. A very weak (r = -0.093) to moderate (r = -0.541) association was found between pathogens in groundwater and on-site sanitation systems (WW from septic tank and sludge from pit latrine). This suggests that the pathogens were not present in the sanitation compartment when they were found in the groundwater and vice versa. Moreover, a very weak (r = 0.007) to moderate (r = 0.525) association was found between the detected contaminants in groundwater and the lateral distance between the OSS facilities and the boreholes. The pathogens detected in all samples showed consistent concentrations, suggesting potential contamination from OSS systems' waste, possibly in groundwater, indicating potential contamination. The siting of OSS facilities at the yards in this study appeared to have a slight influence on the contaminants detected in groundwater. This study calls for an education program to be implemented by the Water and Sanitation Services Authorities to prevent contamination of groundwater and the risk of waterborne diseases.