Improved sanitation, including proper human waste treatment and disposal, is one of the most effective measures for improving public health globally (Sedlak 2014). It remains a challenge, however, in many parts of the world (Figure 9.19). Growing megacities, especially in Africa and Asia, do not have adequate sanitation services to accommodate population growth, contributing to open defecation and poor or non-existent wastewater treatment and disposal (UNEP 2016b; UNEP 2016d). Even in areas with improved sanitation, large-scale septic tank and leachfield use in many expanding urban centres affects downstream water supplies as well as groundwater quality.
Approximately 1.4 million people still die annually from treatable diseases associated with pathogen-polluted drinking water and inadequate sanitation, with many millions of others becoming ill (Lozano et al. 2013). An estimated 2.3 billion people still lacked access to improved sanitation in 2015. While almost all developed countries had achieved ‘universal sanitation coverage’ by 2015, only four of the nine developing regions met the sanitation target (Caucasus and Central Asia, East Asia, North Africa, West Asia). The population proportion served by improved sanitation was particularly low in parts of Oceania, sub-Saharan Africa and South Asia (WHO and UNICEF 2015).
There are significant inequalities in access to improved sanitation between rural and urban areas. About 82 per cent of the global urban population has access to improved sanitation, compared with only 51 per cent of the rural global population (WHO and UNICEF 2015). Public sanitary facilities tend to be regulated at local level in most countries. Where facilities are inadequate, they are often especially so for women and girls, including those located in markets, public transport stations and public event venues. Inadequate sanitation in schools has a deleterious effect on education, especially for girls. The problem is compounded for people living in slums and informal settlements lacking access to adequate drinking water and sanitation facilities, or to durable housing, sufficient living area and security of tenure.