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 background 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 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.