Sanitation and hygiene
Access to safe, affordable water and adequate, equitable sanitation and hygiene is vital for reducing the burden of disease, mortality and school drop-outs – as well as contributing to improving health, dignity, equality, and the overall welfare and productivity of populations. Adequate access to water, sanitation and (gender-sensitive) hygiene (also referred to as WaSH) is therefore essential for sustainable development and social progress.
Despite substantial improvements in access to basic water and sanitation services achieved during the past 15 years, progress has been spread unevenly – generating large disparities across countries, as well as between rural and urban areas.
Across the developed world, widespread access to WASH facilities are often taken for granted. Yet, in low- and middle-income countries, this basic right is often unfulfilled. Currently 844 million people (or, one in 10 of the earth’s population) still don’t have access to a safe, clean drinking water source – if looking at just the world’s least developed countries (LDCs) the number of people without access increases to nearly 4 in 10 people.
Worldwide, an estimated 2.3 billion people also lack access to basic sanitation facilities, of which some 892 million people are forced to practice open defecation. Availability of basic handwashing facilities with soap and water – recognised as a key means of reducing disease transmission – is also weak, with as few as 27 per cent of people having access in LDCs. Across many developing countries, menstrual hygiene management is extremely challenging for women, often leading to adverse health effects, and missed opportunities for social progress.
Collectively and individually these challenges are slowing social progress, and risking the attainment of other global development goals. Inadequate access to safe, clean drinking water, sanitation and hygiene facilities for example threatens steps being taken to improve good health and wellbeing (SDG3) worldwide. This includes over 260,000 children who die from preventable diarrheal diseases caused by dirty water and poor sanitation (a number that equates to the death of a child every two minutes).
Moreover, more than half of all neglected tropical diseases (including intestinal worms, schistosomiasis, and trachoma) are WASH-related, resulting in a range of health problems from visual impairment to impaired cognitive functioning. These diseases are also responsible for half of all cases of malnutrition – even in areas where there is access to sufficient food.
Untreated wastewater from the poor management of sanitation and hygiene facilities (in terms of ill-functioning toilet systems and leaking septic tanks) also creates significant environmental challenges, contaminating soil, and water intended for agriculture uses – leading to negative impacts on food security (SDG2), life on land (SDG15) and below water (SDG14), and ultimately on the household incomes of local communities (SDG1 and SDG8).
No less important are safety issues. Where drinking water is not available locally, people may have to travel considerable distances to access a safe, clean water source. The long trips disproportionately fall to women and children. The time used for collecting and treating water (to make it ready for drinking, cooking and personal hygiene) significantly diminishes their full prospects in life – increasing risks of sexual abuse, disease and dropping out of school, while reducing the time they have available for leisure, household tasks and economic activities (significantly diminishing progress in achieving nearly every aspect of the UN’s sustainable development agenda).
Increasing access to water, sanitation and hygiene is not only an end, but it’s also a driver for a wide range of associated sustainable development goals – from public health and food security, through education and gender equality, to environmental protection, poverty alleviation and the overall economic growth of countries.
Achieving worldwide WaSH goals through technology
Combined with financing schemes and educational campaigns, affordable technological solutions are a key driver for progressing global WaSH goals. Often very simple in design, technologies such as standpipes, pumps, water towers and tanks, alongside sinks, toilets, septic tanks and sewers, provide cost-effective access to water, hygiene and sanitation. The manufacture of these technologies is enabled by a broad variety of minerals and metals.
Piped groundwater supply
In areas where groundwater supply is abundant and population density is large enough, water can be transported through piped networks directly into buildings. Tubes and pipes come in various sizes and types, and are largely made of steel, galvanised steel and iron, as well as cast iron and copper. These materials are corrosion-free, can withstand high water pressures and are easy to install. Some of the older systems used concrete, lead and clay, while newer materials such as plasticised polyvinyl chloride (PVC) and high-density polyethylene (HDPE) are also widely used. Plumbing components (such as valves, elbows, tees, and unions) made of stainless steel, copper or brass and are essential for connecting the pipes and end-use devices together.
Standpipes and wells
Remote rural areas often rely on public taps and standpipes – composed of brass taps, support columns (usually galvanised steel encased in a PVC pipe filled with concrete), and concrete platforms. In smaller communities, simple hand-drilled tube wells and machine-drilled boreholes are used. These wells can be improved with lining and underlining made of brick, cement block, or concrete rings (to seal against contamination and allow for constructing deeper wells), well heads (comprising metal cover, concrete slab, well rim and apron seal), and brick or cement block well reducer rings.
In terms of water lifting devices, where imported piston pumps (such as brass-lined cylinder borehole pumps with metal foot and piston valves, and cast iron outer casing and end fittings) are too expensive, rope pumps, treadle pumps (made of galvanised pipes) and Canzee pumps (made of stainless steel, to avoid corrosion) are a cheaper solution. More advanced options are electric or engine pumps running on gasoline or diesel, and pumps powered by renewables, such as solar. Solar cells are manufactured using aluminium, iron, lead, nickel, silver, copper, zinc, cadmium, tellurium, indium, gallium, and selenium.
Where groundwater is scarce, desalination produces water for drinking, industrial and agricultural use by removing salts and other minerals from seawater. Reverse osmosis desalination pumps saline water under high pressure through semi-permeable membranes, while thermal desalination uses heat to evaporate and condense water. Reverse osmosis is enabled by polymeric membranes, fibreglass tubes, plus polypropylene and thermoplastic pressure vessels, while thermal desalination tubes, brine heaters, evaporator shells and water boxes are made from copper-base alloys, aluminium bronzes, stainless steel and titanium – resistant to corrosion under high chloride and temperature conditions.
Pumps, valves and pipes for water distribution are made of stainless steels and nickel-base alloys which are resistant to high fluid velocities, cavitation and corrosion fatigue. In pre-treatment, anthracite, sand and gravel are used to remove algae, organic materials and other particles from the seawater, while lime, fluoride and carbon dioxide are used during the post-treatment process to remineralise desalinated water and make it drinkable. The infrastructure required for desalination plants (from sea tunnels to sedimentation tanks) also require large amounts of concrete and stainless steel to ensure corrosion resistance, ductility and durability.
Safe water storage
Water storage mitigates against discontinuity of water supply while preventing re-contamination of already treated water. Large-scale solutions for supplying communities with safe water for domestic and livestock needs range from plastic tanks of different sizes, to underground cisterns (often made of concrete, brick or stone, set with mortar and plastered with cement on the inside) and water towers or tanks made of ferro-cement.
Water towers (essentially large, elevated tanks attached to a pump, which lifts the water from a reservoir or water treatment plant) pressurise the water supply, enabling distribution to individual buildings. They also safely store water reserves in case of pump failures. In developing countries, where unsafe water storage is one of the largest challenges, water towers are additionally used for storing water collected through rainwater harvesting, by solar water pumps, or by tank trucks. In the past, these towers were built from bricks, but this has largely been replaced by concrete and steel.
As with safe and affordable water access, toilets are often taken for granted in the developed world. In developing countries, they are less common, but remain key to sanitation, allowing safe disposal of excreta in situ or safe treatment off-site. Of the wet (or water-based) toilet technologies, cistern-flush and pour-flush toilets and urinals are largely produced from porcelain, plus stainless steel or copper in the metal tank fixtures. While convenient for users, wet toilets use large amounts of water for flushing. In response to this, dual flush or water-saving toilets have been developed, while the use of lower-grade water for flushing also helps to alleviate pressures on water scarcity. Dry toilets – such as latrines and composting toilets – operate without flush water, and are suitable for areas where water is scarce, and the groundwater table is low. They are usually built from locally available materials (and fitted with pedestals and slabs made of concrete), or porcelain and stainless steel.
The safe collection, storage, transport and treatment of sewage is key for sanitation and preventing faeces from contaminating the environment. While public sewer connections are used predominantly in urban areas, off-site systems are more common in rural settings. The main facilities are mortared pits for both wet and dry toilets, septic tanks (made of concrete, fibreglass, or plastic), as well as anaerobic filters (which use gravel, crushed rocks, bricks, cinder or pumice to filter particles and degrade organic matter). Sewage either undergoes aerobic or anaerobic filtration, dehydration, or composting within the pits, or is transported (by vacuum trucks or a sewer network) to centralised treatment facilities. A sewer network provides a safe and hygienic means of transporting wastewater in areas with sufficient urban population density and reliable water supply, and is typically made of concrete, PVC, and ductile or cast-iron pipes.
Handwashing with soap is a cost-effective public health intervention, key to reducing the leading causes of child mortality: diarrheal and respiratory infections. Alongside hygiene promotion programmes and educational campaigns, a sustained and consistent practice of washing hands is enabled by hygiene facilities, such as handwashing stations. In the developed world, sinks are usually ceramic, stainless steel or enamel, with stainless steel or brass taps. In remote or low-income areas of developing countries, handwashing facilities are more basic and use locally available materials.
For example, tippy-taps are made of large cans, bottles or pots, while tap-up hand sinks consist of buckets with brass or copper valves. Somewhat more complex are basins made of concrete and tiles, or galvanised basins riveted to a framework of steel bars or PVC pipes. When connected to cisterns and drainage, they contain, transport and regulate the flow of water for group handwashing in schools through punched plastic pipes or drilled galvanised steel pipes, plus taps and valves to regulate water distribution. Where soap is not available, ash, soil or sand is used as a replacement.