Life-giving water poses a public health problem when sanitation systems fail or are simply nonexistent—an all too common problem in many communities. Poor sanitation can contribute to the spread of disease by contaminating drinking water. Untreated waste builds up and poisons river systems, lakes, and other water sources. The lack of sanitation facilities, and training in their use and maintenance, may also provide breeding opportunities in stagnant waterbodies for insects that help to spread disease.
Billions of people, some 40 percent of the world’s population, lack proper ways to dispose of their own waste. The diseases spawned by this problem, including cholera, typhoid, schistosomiasis, infectious hepatitis and polio, cause four percent of all the world’s deaths and nearly six percent of its disability and ill health. The poor, especially the young, are hardest hit.
The sanitary situation can be dire in crowded urban areas, where sewage accumulates rapidly and infectious diseases can spread quickly through the population. However, urban dwellers are more likely than their rural counterparts to have access to basic sanitation facilities.
Technologically, the solution is relatively simple—isolate water supply systems from sewage, and prevent people and insects from contacting human excreta. In practice, however, this problem can be a difficult one largely because many people simply do not realize the health issues caused by unclean drinking water.
In rural areas, simple compost latrines can dramatically improve local sanitation. In cities, particularly in slums, the infrastructure requirements are more challenging. These communities produce large quantities of waste that must be contained and treated before being discharged back into groundwater or surface water. Much of the world fails in this task.
Wastewater treatment of any kind is a rarity in Africa. In Latin America and the Caribbean, only about 14 percent of all wastewater is treated; and in Asia perhaps 35 percent is treated. Even in the developed nations of Europe and North America, large quantities of untreated wastewater released into the environment may overwhelm the natural system’s ability to treat it prior to human contact.