WASH directly impacts environmental conditions. Poorly planned WASH projects, which incorrectly collect and dispose of human excreta, wastewater, solid waste and sludge, can negatively impact communities and ecosystems downstream. The poor and most vulnerable populations are the most likely to be affected by water-related climate change impacts such as more severe and frequent droughts and floods.1 Lack of water and sanitation in emergency situations, such as floods and droughts, leads to increases in diarrheal disease and other health problems.2
Untreated Human Waste
Untreated human waste has detrimental effects on both the environment and economy. The most significant sources of water pollution are lack of treatment of human wastes and inadequately managed and treated industrial and agricultural wastes.3 Ninety percent of sewage is discharged untreated into rivers in the developing world4 and the number of “dead zones” – deoxygenated zones that harm marine life and can be caused by untreated waste – in the world’s seas and oceans may now be as high as 200.5 The Global Burden of Human Disease, caused by sewage pollution of coastal waters, is estimated at 4 million lost ‘man-years’ annually, which equals an economic loss of approximately $16 billion US a year.6
Improvements in WASH can lead to sustainable solutions to environmental conservation and climate change issues around the world. Integrated Population, Health and Environment (PHE) approaches acknowledge the critical links between human health and freshwater ecosystem services, that support human societies. In Madagascar, PHE projects have helped reduce incidence of diarrheal disease in vulnerable communities by combining access to drinking water, family planning, and conservation.7
Ecological sanitation is a closed loop system that emphasizes conservation of water, protection of aquatic ecosystems in addition to health. This approach utilizes less potable water, reuses wastewater for irrigation and safely recycles human waste as fertilizer, preventing contamination of ground and surface waters.8 Ecological sanitation provides the same degree of health protection as more sophisticated and costly water borne sanitation systems (flush toilets).9 Solid waste gives off methane and other gases while decomposing. This biogas can be captured and reused to provide energy for cooking or lighting a home.
 Singh, RB, et al. The influence of climate variation and change on diarrheal disease in the Pacific Islands. Environmental Health Perspectives. 2001; 109(2):155-59. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240636/.↩