Investigation into untreated greywater reuse practices by suburban households under the threat of intermittent water supply

Untreated greywater reuse at the household level is an accessible water source to supplement non-potable water requirements in times of emergency water curtailments but poses various risks to the consumer, the wider community, infrastructure and the environment. Little information is known about unregulated, untreated greywater reuse practices under emergency conditions in suburban communities where consumers have become accustomed to reliable potable water supplied via a pressurised, piped distribution system. There is a lack of knowledge regarding the sources of greywater used, collection methods, storage and distribution of greywater, the application points, the level of treatment (if any) and the perceived risks associated with the greywater reuse. The City of Cape Town was selected as a case study site for research into greywater reuse under the threat of ‘Day Zero’ and stringent water restrictions, implemented during the 2017/2018 summer season. A consumer survey and analysis of relevant online forums was conducted in order to obtain the necessary information. Greywater reuse practices from a sample group of 351 consumers were identified and classified. Untreated greywater reuse was found to be common, mainly for garden irrigation and toilet flushing. The results point to high-risk activities in the study group.