Social perception and risk assessment of domestic uses of solar pasteurized rainwater in an informal settlement community

Abstract

Solar pasteurization systems (SOPAS) were analysed on-site in a South African informal settlement, for the treatment of rainwater. This was achieved by (1) gauging community members’ perception of rainwater harvesting (RWH) and envisioned uses, (2) monitoring the removal of opportunistic pathogens in the rainwater [qPCR assays in combination with viability pre-treatment], and (3) applying quantitative microbial risk assessment (QMRA) to assess the risk of using the untreated and SOPAS treated rainwater for domestic activities identified by community members. Overall, 61% of respondents were familiar with the concept of RWH and 67% were favorably inclined towards using rainwater for daily household needs. Respondents also indicated that access to warm water, from the SOPAS system, may decrease household reliance on fossil fuels to heat water for various activities. Viability qPCR analysis showed that the SOPAS system reduced Legionella spp., Pseudomonas spp., and Salmonella spp. cells by a mean of 94.4%, 98.6%, and 88.3%. Additionally, Pseudomonas spp. and Salmonella spp. were reduced to below the detection limit at > 73 °C and > 75 °C, respectively. Subsequently, QMRA for all three target pathogens showed that SOPAS treatment primarily reduced the health risk associated with using the treated water for washing/bathing, cleaning, and washing laundry, amongst others, to below the 1 × 10−4 annual infection benchmark limit. The study highlights the importance of community engagement, through social perception studies and community workshops, prior to the implementation of water treatment interventions, as well as the value of combining molecular-based assays with QMRA to inform safe water uses.