An appropriate technology is a small-scale, sustainable, and decentralized application of technical innovation. Dr. Ernst Friedrich Schumaker popularized this ideology with his influential book, Small is Beautiful. Appropriate technologies are particularly suited for low-income countries because they are environmentally friendly, energy-efficient, and people-centered instead of machine-centered. Low-income countries are countries with a per-capita national income of less than $1,026, as defined by the World Bank. This term often refers to countries previously known as “developing” or “third world”, two terms no longer frequently used due to their negative insinuation and lack of basis in fact. These countries face higher rates of death and illness, frequently due to lack of clean water and sanitation. The significance of this issue is highlighted by the United Nations in Goal 6 of their Sustainable Development Goals for 2030: “Ensure availability and sustainable management of water and sanitation for all.”
Appropriate technologies came as a reaction to the US foreign aid projects of the 1950-70s, such as the Point Four Program. As The Ugly American, published in 1958 by William J. Lederer, illustrates, US foreign aid during this time was ill-informed, insensitive, elite-favoring, and often simply for show . These projects focused on introducing large and infrastructural systems, with a manifest function of providing economic and technical aid to low-income countries and latent functions of winning favor over the USSR, promoting markets for US exports, and pushing US-style economic systems over communism . Appropriate technologies were a response to such impersonal and ineffective strategies.
One particularly pertinent application for appropriate technologies is supplying plentiful, clean drinking water to low-income countries. Clean water in high-income countries is typically supplied by large-scale utility companies, whereas water in low-income countries is primarily collected by the end user.  Thus, water purification and distribution technology tends to be small and employed at the point of use. Appropriate technologies for water purification are easily maintainable, low-cost, durable, sustainable, environmentally friendly, and intuitive.
Although safe, clean, and plentiful drinking water is a necessity for a healthy life, roughly one in ten people worldwide, or about 663 million people, lack access. Every 90 seconds, a child dies from a water-related disease, such as schistosomiasis or cholera. In low and middle income countries, one third of all healthcare facilities lack a safe water source. 
The lack of clean drinking water in low-income countries is a self-compounding problem that taxes local economies significantly. Due to water-related diseases, the sick and their care-givers are unable to contribute to their community. Healthy citizens waste valuable time hauling clean water over long distances that could instead be spent working to earn income; a vicious cycle results .
While there are many viable water purification solutions, choosing a technology that is appropriate for the capabilities of a given community can be complex. Where one technology might be suitable from a technical standpoint, it might be an inappropriate fit for the social, cultural, institutional, or economic environment of a community. A study of how appropriate water distribution technologies have been deployed in communities around the world can shed some light on the complexity.
Ceramic Filters purify water by separating out microorganisms via microscopic pores. While effective at removing bacteria, protozoa, and microbial cysts, they do not remove viruses and chemical pollutants. Silver-impregnated designs kill any lingering bacteria that make it through the filter. Ceramic filters can reduce fecal coliform counts by 99.9%  and the incidence of diarrheal diseases by up to 70%. 
Potters For Peace (PFP) created a design that is cheap to manufacture and provides up to 20 liters of water per day for 3 years. However, it is not without issues; the filters require regular scrubbing to clear clogged pores and prevent bacterial growth. Replacement parts are needed for breakdowns and the entire system has a lifespan of only a few years; thus, a constant supply of filters is needed to sustain a large community. To this end, PFP established local ceramic filter factories.
After the 2004 Indian Ocean Earthquake and Tsunami, the American Red Cross and the Sri Lanka Red Cross Society provided communities in Sri Lanka with ceramic water filters. Through continued re-visits, the Red Cross staff members explained proper use and care of the filter as well as the importance of general sanitary practices. Bacteria tests confirmed successful implementation of the filters. A few years after the tsunami, local pottery manufacturers began producing replacement ceramic filters, ensuring the system’s longevity. The Red Cross’s attention to the education and training of beneficiaries was crucial to the project’s success. 
Slow Sand Filtration
Gravity-driven slow sand filters (SSFs) pull water through sand and gravel to filter bacteria and microorganisms. SSFs typically remove 99.98% of protozoa, 90-99% of bacteria, and 80-98% of E. coli. .
[[w:Samaritan’s_Purse|Samaritan’s Purse], a Christian humanitarian organization, has installed SSFs in individual households in over 24 countries. Although seemingly beneficial, when outside NGOs provide free technologies to communities, beneficiaries lack a sense of ownership. To combat this, Samaritan’s Purse requires that those interested in receiving a filter must cover part of the initial cost, attend training sessions, and assist with the transportation and construction. Unfortunately, villagers found these requirements to be prohibitive and thus the SSF was not widely adopted. 
A research group from the University of Virginia studied a SSF system that had been installed by an outside NGO in a rural Nicaraguan community. Although the system functioned properly when first installed, it had since ceased to deliver its promised results. Through a series of interviews, the team learned that the community had never been taught how the SSF worked or how to properly maintain it. Additionally, the community did not understand the importance of a maintenance budget and making timely system repairs. Because the community lacked the organizational tools to sustain the SSF, the system fell into disrepair and they eventually opted to bypass the filter entirely. 
WASHTech has implemented many SSFs along the Volta River in Ghana, where groundwater is scarce and of poor quality. Because the communities in this region are more financially stable, they can afford the SSF’s high construction cost. WASHTech’s SSFs have been successfully sustained due to an emphasis on beneficiary training in use and maintenance. WASHTech recommends that system operators periodically receive refresher training and that regular water quality tests be carried out to ensure system functionality. 
The Roundabout PlayPump, primarily implemented in South Africa, Swaziland, Zambia, and Mozambique, promised to harness the energy of playing children to pump clean groundwater. The award-winning system freed women from labor intensive pumping, offered children a new playground, and encouraged girls who were now relieved of their water-fetching duties to attend school. Additionally, the pumps were intended to be partially self-sustaining by displaying advertisements and billboards. The parts were produced locally in South Africa and a maintenance phone number was displayed on each pump.
Unfortunately, the PlayPump failed to meet expectations. The system cost $14,000 to install, which is sufficient to buy several conventional hand pumps, and up to 75% of PlayPumps did not carry the promised advertisements to offset this cost. Furthermore, in order to provide the recommended minimum of 15 liters of water per person, it was calculated that children would have to spend 27 hours every day playing on the pump. . If the children were occupied, the village’s women would have to operate the PlayPump which was much more labor intensive than a simple hand pump. For communities outside South Africa, replacement parts would take months to arrive. Due to a diminished feeling of local ownership, community beneficiaries lost interest in the project and the company lost funding. Ultimately, PlayPumps International donated their remaining inventory to Water For People as they shifted focus to solely maintaining existing pumps. 
Solar disinfection uses the sun’s UV rays to kill microorganisms and sterilize drinking water. Six hours of sun exposure can remove up to 80% of diarrhea-causing pathogens from water in a clear bottle. Because it is a point-of-use technology, solar disinfection reduces the chance of secondary infection.
The Swiss Federal Institute of Aquatic Science and Technology (EAWAG)  provides reusable solar disinfection plastic bottles to households in low-income countries. EAWAG admits that the most challenging aspects of implementing a solar disinfection system are not technical, but social in nature; their challenges include educating community members on how solar disinfection works and the importance of general sanitation. Since solar disinfection is an active form of water purification, it requires a lifestyle change, which can discourage end users.
Chlorine in drinking water kills microorganisms, bacteria, and viruses, while protecting the water from recontamination. Chlorination, however, is ineffective against protozoa and in turbid waters. Chlorine also alters the taste of water, and excessive ingestion can lead to long term side effects.
Joseph Arvai and Kristianna Post studied the implementation of water boiling, solar disinfection, ceramic filters, and chlorine disinfection in two rural villages in Tanzania. The two forms of chlorine disinfection included WaterGuard, a sodium hypochlorite tablet, and PUR, a hypochlorite disinfectant that also removes sedimentation with flocculant particles. The team explained to the villagers the risks of untreated water and identified the villagers’ domestic water objectives. With the non-negotiable exception of water safety, the objectives were determined by the villagers after a demonstration of each of the point-of-use water treatment options.
In both villages, the end results matched: The preferred filtration method was WaterGuard. Boiling water was perceived as time-inefficient, and in some cases, villagers did not like the taste. Solar disinfection in both cases was eliminated because it failed to adequately purify the water and the ceramic filters did not arrive in Milola. In Naitolia, the villagers thought the ceramic filter gave the water poor taste, color, and odor. Although PUR filtered the water more effectively than WaterGuard, its ability to remove cloudiness and sedimentation was so efficacious that the villagers deemed it “supernatural” and would not use it. While WaterGuard was only semi-effective from a technical standpoint, this solution was chosen because the villagers trusted it and thus were unlikely to abandon it .
Another application for appropriate technologies is improving sanitation. As of 2019, 2 million people lacked access to basic sanitation (toilets or basic latrines) . The result is contaminated water, water-borne illness (cholera, typhoid, infectious hepatitis, polio, rotavirus, etc.), and malnutrition (due to intestinal parasites in contaminated water). Poor sanitation kills ~1.7 million people annually, including 4,000 child-deaths a day. The cholera outbreak in Haiti illustrates the kind of devastating impact poor sanitation can have. After the Haiti earthquake in 2010, many Haitians had to live in tents and drink contaminated water, leading to a huge outbreak of cholera that lasted for years . Less obviously, lack of sanitation can constitute a human rights issue, forcing women to expose themselves to the danger of sexual assault as they leave the safety of their homes at night in search of a private place to defecate. Lack of sanitation in schools can also deprive girls from a chance at education . Improving sanitation would not only save millions of lives and contribute towards women’s safety and education, but would also yield $9 for every $1 spent as a result of saved time, reductions in medicine and health costs, improved quality and amount of education for girls, and protected water resources. The World Health Organization, the United Nations, the Bill and Melinda Gates Foundation, and The Borgen Project are some of the organizations leading the way to improved sanitation.
Nanomembrane toilets dispose of liquid and solid waste by purifying liquid waste and heating solid waste, creating ash and thermal energy. The nanomembrane toilet utilizes a unique rotating mechanism for flushing that uses no external energy or water. Liquid waste is purified by a transition to a gaseous form and then filtering, separating out pathogens and volatile odorous compounds. The purified liquid can then be used for washing and irrigation. The solid waste is dried and then burned to produce thermal energy that can then be used to power the liquid filtration. Any excess energy can be used for low voltage items .
The nanomembrane toilet was invented by Cranfield University and is funded by the Bill and Melinda Gates Foundation via the Reinvent the Toilet Campaign. The Reinvent the Toilet Campaign focuses on improving the toilet in low-income countries at a low cost, without relying on a water supply or sewer systems . The toilet is still in the development stages and should have a testable prototype soon . If the nanomembrane toilet works as expected, many low-income countries will benefit, as their waste will be turned into energy and clean water.
A standard pit latrine or pit toilet consists of a slab with an opening for waste, a hole in the ground for waste collection, and a shelter for the slab and hole. These are commonly used in low-income countries due to their low production cost. The WHO recommends that pit latrines are placed 30 meters away from water sources at a minimum .
Pit latrines are used as a more sanitary alternative to open defecation. Open defecation plays a major role in unsanitary water due primarily to runoff and direct contamination of otherwise usable land and clean water sources. There are many factors that lead to open defecation, such as the lack of established defecation locations, the lack of awareness of potential health risks, and certain cultural beliefs. For example, there is a belief in Madagascar that using outhouses can cause a pregnant mother to lose her expecting child.
Many countries are working to decrease open defecation. The Indian government, for instance, started a campaign called Clean India Mission in 2014 to decrease open defecation in rural areas. They do this by educating citizens, giving them money to obtain a pit latrine, or by withholding basic electricity until a pit latrine is purchased or built. The campaign has seen mixed results in many rural areas. Those who live in areas with pit latrines will often continue practices of open defecation, using the pit latrine to wash their clothes or bathe. Defecating in the open is seen as a better option for many as it is natural and farther away from their homes. Pit latrines are generally placed closer to the home or town to provide quick access, leading many to worry about flies, smell, and sickness . Thus, in order to promote greater use of pit latrines and lower levels of open defecation, pit latrines must be improved.
One example of a redesigned pit latrine is SanPlat. SanPlat is a plate that covers the hole of the latrine, and has been proven to be effective in reducing both the odor and the number of insects in the pit. Through restricting air flow in and out of the pit and light from the pit, the SanPlat upgrades an unimproved sanitation facility to an improved facility .
Notable advancements in drinking water coverage have been made since the end of the 20th century. Between 2000 and 2017, the WHO and UN have documented that 1.8 billion people gained access to basic drinking water services and the population drinking surface water decreased from 256 to 144 million . The Millennium Development Goal set by the UN to halve the percentage of people without access to improved drinking water by 2015 was met and exceeded by three percentage points .
Appropriate technologies in improved drinking water are typically non-piped. Non-piped improved drinking water services are particularly effective in increasing drinking water coverage in rural areas. Between 1990 and 2015, non-piped improved services were responsible for 18% of the growth in improved drinking water coverage in rural areas of low-income countries, compared to 1% increase from piped services . Over 2 million people use solar disinfection daily for their drinking water services across 28 low-income countries . Another 200,000 use one implementation of slow sand filtration, BioSand filter, for their drinking water services .
Appropriate technologies have led to significant progress in sanitation over the past two decades. The United Nations’ and World Health Organizations’ documented efforts to increase improved sanitation facility coverage has shown 2.1 billion people gaining access to improved sanitation between the years 2000 and 2017 . Nearly half the 1.3 billion practicing open defecation in 2000, 627 million people, now have access to a sanitation facility .
For low-income countries and rural communities, onsite sanitation is an effective means of increasing basic sanitation coverage. In the UN-defined Least Developed Countries, the proportion of the population using improved onsite sanitation facilities increased by 17%, compared to only 1% increase in use of sewer connections . Among onsite sanitation solutions, pit latrines and other improved facilities are used by 67% of those in rural communities. Use of onsite sanitation also varies within countries with respect to wealth. In countries like Armenia and Mongolia, sewer connections are common among the richest quintile but onsite sanitation is more common among the poorest quintile . As a result, appropriate technology improvements to onsite sanitation can have a greater impact on the economically disadvantaged communities within a country as well as low-income countries overall.
Of those using improved sanitation facilities, 1.6 billion used improved pit latrines. Appropriate technology improvements to simple pit latrines have led to an increased number of improved sanitation facilities. Between the years 2007 and 2015, usage of improved pit latrines in Sub-Saharan Africa increased by 49%, with 83% of the improved pit latrines incorporating appropriate technologies such as slabs or vertical vent pipes .
While technologies in low-income countries must be technically sound, it is even more crucial that they account for the unique needs and capabilities of the humans that they serve. Often, the best technical filtration solution can be rendered ineffective by a villages’ lack of understanding, organizational capacity, or even superstitious beliefs. When implementing a technology in low-income countries, endowing a sense of ownership and responsibility to the end user leads to greater success. While further examination is needed to extend this study of appropriate technologies beyond clean water and sanitation, the lessons learned here-in are widely applicable.