No one should be without clean water and sanitation
Achieving worldwide WASH goals through tech
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.
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.
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.
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.