Figure 9.9: Global physical and economic water scarcity
Physical and economic water scarcity Not estimated
Little or no water scarcity Physical water scarcity
Approaching physical water scarcity Economic water scarcity
Source: WWAP (2012, p. 125). 9
in 2000. About half of United States waters do not meet standards protective of aquatic life, with more than 40 per cent not meeting recreational-use standards (UNEP 2016a). The water quality of many lakes and reservoirs is particularly endangered worldwide because of their long water residence times and tendency to accumulate pollutants (International Lake Environment Committee Foundation [ILEC] and UNEP 2016).
Groundwater pollution sources include non-point agricultural and urban run-off, on-site wastewater treatment, oil and gas extraction and fracking activities, mining, and industrial sources (Foster et al. 2016). Natural contamination occurs in some cases (e.g. sodium-chloride salinity, arsenic, fluoride,
radioactivity in fossil groundwater aquifers). Human health impacts from untreated groundwater are of particular concern (Morris et al. 2003; UNEP 2016e).
9.5.1 Pathogens
Water-borne diseases remain major challenges in many African, Asian, Pacific and Latin American cities and rural communities (Annex 9-1). Although collection and treatment of human excrement has largely curtailed the problem in developed countries, sewage outfalls still generate large pathogen loads. However, parasites can survive waterbody conditions for many weeks, while viruses may survive drinking water treatment.
