Sanitation
Sanitation begins with a single, unglamorous goal: keeping human waste away from human mouths. The route it tries to block even has a name in the field, the fecal-oral route, and the diseases it carries read like a roll call of human misery. Diarrhea, a main cause of malnutrition and stunted growth in children. Cholera, hepatitis, polio. Worm infections like ascariasis, plus schistosomiasis and trachoma. All of them spread more easily where sanitation is poor. The defenses against them can be as simple as washing hands with soap or as vast as a city's sewers. Yet in 2017, by one estimate, 4.5 billion people had no safely managed sanitation at all. How did something so basic become a measure scored on ladders, written into human rights law, and counted among the world's development goals? And why does a problem with such an obvious fix remain unsolved for billions?
The World Health Organization defines sanitation as the provision of facilities and services for the safe disposal of human urine and faeces, plus the upkeep of hygienic conditions through services like garbage collection and wastewater disposal. That sounds tidy, but the term refuses to sit still. Different countries and organizations draw its borders in different places. In its fullest sense, sanitation spans four systems: excreta management, wastewater management including treatment plants, solid waste management, and drainage of rainwater, also called stormwater drainage. Many in the WASH sector, however, narrow the word to excreta management alone. The Water Supply and Sanitation Collaborative Council casts a wider net, defining sanitation as the collection, transport, treatment and disposal or reuse of human excreta, domestic wastewater and solid waste, along with associated hygiene promotion. A 1998 DFID guidance manual chose a tighter meaning, taking the word alone to mean the safe management of human excreta. That same manual draws a useful line. It reserves the phrase environmental sanitation for the wider job of controlling all the physical-environment factors that may harm human health and well-being, which in developing countries normally folds in drainage, solid waste management, and vector control. Sanitation also reaches into the home and the street. Personal sanitation can mean handling menstrual waste, cleaning household toilets, and managing household garbage. The people who do the public versions of this work, cleaning drains, sewers, and public toilets or operating sewage treatment plants, are called sanitation workers.
The F-diagram is sanitation's clearest picture of the enemy. It maps the major routes of fecal-oral disease transmission, and every one starts with the letter F: feces, fingers, flies, fields, fluids, food. Effective sanitation systems place barriers along those routes, separating excreta from people so the disease cycle breaks. Providing those barriers means treating sanitation as an entire system rather than a single object. The sanitation chain runs from the user's experience through the collection of excreta and wastewater, then transport and treatment, and finally reuse or disposal. Skip any link and the chain fails. The capture, storage, transportation, treatment and disposal or reuse of human excreta and wastewater all belong inside one sanitation system. Reuse can target the nutrients, water, energy or organic matter held in excreta and wastewater, an idea named the sanitation value chain, or the sanitation economy. The technologies that carry this out range widely. At one end sit centralized civil engineering works: sewer systems, sewage treatment, surface runoff treatment and solid waste landfills. At the other end sit simple onsite systems, sometimes nothing more than a pit latrine or another non-flush toilet for the excreta part. Infrastructure has to bend to its setting, fitting both consumers' expectations and the local resources at hand.
The sanitation ladder, defined by the Joint Monitoring Programme in 2016, turns a basic human need into a measurable scale. It begins at open defecation and climbs through rungs labeled unimproved, limited, and basic, with safely managed at the top. The framework is especially relevant to developing countries. In 2017, JMP gave its rungs sharper edges. A basic sanitation service became the use of improved sanitation facilities not shared with other households, while a limited sanitation service meant improved facilities shared between two or more households. Safely managed sanitation, the highest rung envisioned by Sustainable Development Goal Number 6, carries the strictest test. It is an improved facility, unshared, where the excreta is either treated and disposed in situ, or stored, emptied and carried to offsite treatment, or piped through a sewer with wastewater and treated offsite. It is measured under Indicator 6.2.1, which also asks whether a household has a hand-washing facility with soap and water. The numbers behind the ladder are stark. A 2024 United Nations estimate found 3.4 billion people lacked safely managed sanitation. As of 2015, an estimated 2.4 billion still lacked improved sanitation facilities, and 660 million lacked access to safe drinking water. The result of going without is usually open defecation, a practice that as of 2015 was still followed by just under one billion people, 946 million worldwide.
For every US$1 spent on sanitation, by a rough estimate, the return to society is US$5.50. That ratio frames why inadequate sanitation registers not just as a health failure but as an economic wound. A World Bank study put the losses to the Indian economy from inadequate sanitation at the equivalent of 6.4% of its GDP. Those losses came from premature mortality, time lost in accessing facilities, lost productivity, and added healthcare costs, with forgone tourism revenue piled on top. The same study found the burden falls hardest on the poor, on women, and on children. A toilet at home pushes in the other direction for women, linked to higher literacy and greater participation in the labor force. Building toilets need not be ruinously expensive. A 2018 study comparing full sanitation-chain systems in developing cities of Africa and Asia found conventional sewer systems were usually the costliest, followed in order by septic tanks, ventilated improved pit latrines, urine diversion dry toilets, and pour-flush pit latrines. Community efforts can drive the figures lower still. A study of Mumbai informal settlements found that US$1.58 per adult would cover construction of a community-managed toilet block, and less than US$1 per household per month would cover maintenance.
In 2010, the United Nations General Assembly recognized the human right to water and sanitation, a right derived from the human right to an adequate standard of living and grounded in human rights treaties, declarations and other standards. Recognition on paper, though, has not closed the gap on the ground, and the slow pace has a long paper trail. At the Millennium Summit in New York in 2000 and the 2002 World Summit on Sustainable Development in Johannesburg, the United Nations set the Millennium Development Goals. The sanitation target for 2015 was to halve the number of people without access to potable water and sanitation, measured against a 1990 baseline. Progress lagged so badly that in December 2006 the General Assembly declared 2008 The International Year of Sanitation. One major reason for the gap is plain: sanitation rarely gets the political attention given to other issues, and water supply projects tend to be emphasised instead. There was movement nonetheless. Between 1990 and 2015, global open defecation rates fell from 38% to 25%. By 2015-82% of the global urban population and 51% of the rural population used improved sanitation facilities. In 2016 the Sustainable Development Goals replaced the Millennium Development Goals, and sanitation landed in Sustainable Development Goal 6, with a target of clean water and sanitation for all by 2030. The COVID-19 pandemic in 2020 sharpened the stakes, since handwashing is one of the most common ways to prevent coronavirus, yet two out of five people have no hand-washing station.
In 2011, the Bill & Melinda Gates Foundation launched the Reinvent the Toilet Challenge, an effort to find safer, more effective ways to treat human waste and bridge the global sanitation gap. Among its targets were technologies like the Omni Processor and tools for fecal sludge management. In 2015, the foundation published a strategy update titled Building demand for sanitation. The newest innovations being tested include locally produced alcohol-based hand rub, novel latrine improvement, and container-based sanitation, three initiatives recognized by the Centers for Disease Control and Prevention. Hardware alone, though, does not deliver health. Studies suggest hygiene practices matter as much to sanitation-related disease as the facilities themselves, which is why hygiene promotion sits at the core of the work. Its three key elements are the mutual sharing of information and knowledge, the mobilization of affected communities, and the provision of essential material and facilities. Building the people and institutions to run all this is its own challenge. In India, the Sanitation Capacity Building platform was funded by the Bill & Melinda Gates Foundation from 2015 to 2022 to help towns and cities plan and implement decentralized sanitation solutions. Its lesson was that capacity development happens best on the job, inside a learning organization culture.
Major human settlements could first take root only where fresh surface water ran plentiful, beside rivers or natural springs. From there, people built systems to bring water in and to carry wastewater out, and the early logic of sewage treatment was simply to convey raw sewage to a river or ocean where it would be diluted and dissipated. The Indus Valley Civilization offers an early case of public water supply and sanitation, reaching back into the Bronze Age between 3300 and 1300 BCE. Ancient Rome built on a grand scale, with stone and wooden drains collecting and removing wastewater from populated areas. Its first sewers were built between 800 and 735 BCE, and one of them, the Cloaca Maxima, emptied into the River Tiber. The modern descendant of these works carries an unexpected cost. Global methane emissions from non-sewered sanitation systems in 2020 were estimated at 377 Mt CO2e per year, about 4.7% of global anthropogenic methane emissions, comparable to the emissions from wastewater treatment plants themselves.
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Common questions
What is sanitation and what does it include?
Sanitation refers to public health conditions related to clean drinking water and the treatment and disposal of human excreta and sewage. In its fullest sense it spans excreta management, wastewater management, solid waste management, and drainage of rainwater, though many in the WASH sector narrow it to excreta management alone.
How does sanitation prevent disease?
Sanitation systems place barriers between excreta and people to break the fecal-oral route of disease transmission. The F-diagram maps these routes through feces, fingers, flies, fields, fluids and food, and adequate sanitation can reduce diseases such as diarrhea, cholera, hepatitis, polio, ascariasis, schistosomiasis and trachoma.
How many people lack safely managed sanitation?
A 2024 United Nations estimate found that 3.4 billion people lacked safely managed sanitation. A 2017 JMP estimate had put the figure at 4.5 billion without safely managed sanitation, and as of 2015 an estimated 2.4 billion people still lacked improved sanitation facilities.
When did the United Nations recognize the human right to water and sanitation?
The United Nations General Assembly recognized the human right to water and sanitation in 2010. The right is derived from the human right to an adequate standard of living and is grounded in human rights treaties, declarations and other standards.
What is the economic return on investment in sanitation?
By a rough estimate, for every US$1 spent on sanitation the return to society is US$5.50. A World Bank study found that economic losses to the Indian economy from inadequate sanitation were equivalent to 6.4% of its GDP.
What is the sanitation ladder?
The sanitation ladder, defined by the Joint Monitoring Programme in 2016, is a scale that begins at open defecation and climbs through unimproved, limited and basic, with safely managed at the top. It is used to compare sanitation service levels within and across countries and is particularly applicable to developing countries.
How old are the world's earliest sanitation systems?
The Indus Valley Civilization shows public water supply and sanitation during the Bronze Age, between 3300 and 1300 BCE. The first sewers of ancient Rome were built between 800 and 735 BCE, including the Cloaca Maxima that emptied into the River Tiber.