The status and quantification of de facto water reuse in South Africa – a review Umhle U. Swana a , Usisipho Feleni a , Tshepo J. Malefetse b , Bhekie B. Mamba a , Peter Schmitz c and Thabo T. I. Nkambule a, * a Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering and Technology, University of South Africa, Florida Campus, Johannesburg 1709, South Africa b Mintek, Randburg 2125, South Africa c Department of Geography, University of South Africa, Florida Campus, Johannesburg 1709, South Africa *Corresponding author. E-mail: nkambtt@unisa.ac.za Abstract The practice of discharging insufficiently treated wastewater to surface water used for potable use (de facto reuse) is common globally. Although de facto reuse provides a sustainable supply of water, it also affects the environment and human health negatively because the inadequately treated effluents contain contaminants of emerging concern (CECs). Therefore, there is a need to determine the extent of de facto reuse in water bodies of South Africa (SA) and thus assess the potential environmental and health risks associated with the reuse of insufficiently treated wastewater in the country. This review summarizes the status of de facto reuse in SA and its negative impact on human health and the environment. Furthermore, the review provides back- ground information on water reuse and as well as the current treatment technologies available in the country for potable water reuse. The use of a geographic information system (GIS) model in combination with caffeine (a wastewater tracer that is abundant in SA surface water systems) for the quantification of de facto reuse is also cited. Such methods, it is envisaged, will enable water management authorities to make well informed decisions regarding water quality issues in SA. Key words: de facto reuse, geographic information system, wastewater effluents, wastewater tracers, water sustainability, South Africa INTRODUCTION Water is one of the most important resources that are essential for sustaining human and aquatic life. However, due to the high prevalence of droughts, global population growth, rapid industrialization and the concomitant urbanization, and the ever-growing water needs of the agricultural sector, pota- ble water has become a limited resource (Lautze et al. 2014). This problem is compounded by the depreciating water quality resulting from pollution by industrial effluent discharges. In fact, water scarcity resulting from the depletion of water resources and the depreciation of the water quality is regarded as the single biggest problem facing arid and semi-arid countries (Adewumi et al. 2010; Chaudhry et al. 2017; Roccaro & Verlicchi 2018). Key factors contributing to water scarcity in South Africa (SA) SA is a semi-arid country plagued by large and unpredictable rainfall variations and high evapor- ation rates (DWA 2013a). Drought, a reoccurring component of the South African climate, is © IWA Publishing 2020 Water Practice & Technology Vol 15 No 2 225 doi: 10.2166/wpt.2020.021 Downloaded from https://iwaponline.com/wpt/article-pdf/15/2/225/703586/wpt0150225.pdf by guest on 29 July 2020