McCarthy et al. (2012) noted that urban storm water is one of the largest sources of contaminants for surface waters. The microbiological pollution most often found in urban storm water originates from failing or non-existent sanitation systems, as well as inappropriate waste disposal and hygiene habits, with the single most frequently encountered pollutant being raw sewage, followed by household greywater (‘sullage’). Urban storm water run-off is an important conduit of microbial pathogens and other hazardous substances, and has the potential to disseminate diseases quite widely given that the destination of much of the urban storm water is the nearest river or other watercourses such as lakes, marshes and wetlands (Neil et al. 2014). The figure shows the percentage of the global population with access to improved sanitation. Sub-Saharan Africa falls within the lowest percentage band.
From collection: Sanitation and Wastewater Atlas of Africa - Ecosystems