Namibia is an arid country that is regularly afflicted by droughts. Large rivers flow only along its northern and southern borders, but they are far from the population centers. They are also far from the country's mines, which are large water users. In order to confront this challenge, the country has built dams to capture the flow from ephemeral rivers, constructed pipelines to transport water over large distances, pioneered potable water reuse in its capital Windhoek located in the central part of Namibia, and built Sub-Saharan Africa's first large seawater desalination plant to supply a uranium mine and the city of Swakopmund with water. A large scheme to bring water from the Okavango River in the North to Windhoek, the Eastern National Water Carrier, was only partially completed during the 1980s.
Most urban residents have access to drinking water supply, but access lags behind in rural areas. Access to sanitation also considerably lags behind access to drinking water supply. The bulk water supply infrastructure is owned by NamWater, a public entity operating under commercial principles. It sells water to the mining companies, as well as to the municipalities which in turn sell it to urban residents and businesses.
Water resources
Namibia's climate is hot and dry with erratic rainfall during two rainy seasons in summer. Within Africa its climate is second in aridity only to the Sahara. Namibia shares several large rivers, such as the Orange River in the South, shared with South Africa, as well as the Zambezi and Okavango Rivers in the North, shared with Angola, Zambia and Botswana. But these rivers are far away from the population centers and the cost of tapping them for drinking water supply is prohibitive. Only the Cunene River, which is shared with Angola, provides drinking water for four Northern regions of Namibia. The total average "safe yield" of Namibia's water resources is estimated at 660 million m3/year, distributed as follows: groundwater 300 million m3/year, ephemeral rivers 200 million m3/year, perennial rivers 150 million m3/year and unconventional sources such as treated wastewater 10 million m3/year.
Groundwater Groundwater is distributed unevenly over the territory of Namibia, thus making the construction of pipelines necessary to tap their potential. In particular, the coastal area is nearly devoid of groundwater. Recharge in these areas is low and unreliable, groundwater lies at great depths and sometimes is of poor quality. Other areas are favorable, sitting on high-yielding, very productive aquifers that contain more water than farmers and communities presently need. Numerous small springs throughout the country sustain wildlife, man and livestock. Over the past century, more than 100 000 boreholes have been drilled in Namibia. Half of these are still in operation. In 2012 hydro-geologists discovered a huge aquifer in Northern Namibia that could supply the area, where 40% of the population of the country lives, for 400 years. The aquifer, called Ohangwena II, contains about 5 billion cubic meters of water which is up to 10,000 years old. The aquifer is about 300 meters deep and is under pressure, so that its water could be pumped up at a relatively low cost. However, a saline aquifer sits on top of the freshwater aquifer, so that drilling must be done carefully in order to avoid saline intrusion. The aquifer receives some recharge from Angola in the North. Experts recommend that, during normal climatic conditions, water abstraction should be limited to the inflow from the North in order to manage the aquifer on a sustainable basis. However, during extended droughts induced by climate change, the aquifer can be drawn down and serve as an important buffer against drought.
In some areas, groundwater is slightly saline (brackish). In the Omusati Region in Northern Namibia, four small brackish water desalination plants were installed in 2010 as part of the German-Namibian research project CuveWaters. The plants are powered by solar energy and provide between 0.5 and 3.3 m³ of safe drinking water per day, enough to satisfy the basic needs of between 10 and 66 people. At 15 Euro/m3 the cost of desalinating brackish water in these small plants is very high.
Surface water
Many of the ephemeral (seasonally flowing) rivers of the Namibian interior are dammed and, according to the FAO, provide a 95%-assured yield of 96 million m3/year, based on historical rainfall data. These dams have low safe yields in comparison to their total volume, because of uneven flows over time and high evaporation losses. Thus only about half the water from ephemeral rivers is usable. There is surplus water in some dams, e.g. in the Oanob Dam, the Hardap Dam, the Naute Dam and the Friedenau Dam. This surplus water cannot be used because of the remote location of these dams and the comparatively limited local demand.
Namibia suffers from regular droughts, the most recent one hitting the country in 2019.
The water from perennial (permanently flowing) rivers used in Namibia corresponds to the small share of Namibia in its border rivers. The actual abstractions as of 1999 (latest available data) were 23 million m3 from the Cunene River at Ruacana, 49 million m3 from the Orange River at Noordoewer, 22 million m3 from the Okavango River (that flows through Namibia in the Caprivi Strip) at Rundu, and 7 million m3 from the Zambezi River. Namibia has agreements in place with Angola and South Africa about the sharing of the Cunene and Orange Rivers respectively. The water allocation from the Cunene River is 180 million m3 and thus far larger than the amount withdrawn.
Flood and rainwater harvesting In Northern Namibia rain is relatively abundant, but it falls only during the rainy season, creating temporary natural ponds called Oshanas. At the height of the rainy season the water in these ponds is clear and of good quality. In a pilot project as part of the CuveWaters research program, in the remote village Lipopo in the Southern Oshana region water from an Oshana has been pumped to a storage tank to be used for the irrigation of vegetables during the dry season using a drip irrigation system. In addition, rainwater is being collected from the rooftop of a greenhouse and from the roofs covering the storage ponds. In another village, Epyeshona near Oshakati, only rainwater is collected, both on an individual basis from the rooftops of houses, and on a communal basis from a concrete area on the ground constructed especially for rainwater harvesting. In both cases the water is used for the irrigation of vegetables during the dry season, either in an open field or in a communal greenhouse.
Seawater desalination The first large desalination plant in Sub-Saharan Africa was inaugurated by Areva on the 16 April 2010. The Erongo plant is located near Wlotzkasbaken, 30 km north of Swakopmund. Its maximum capacity is 20 million m3 per year but it will initially supply 13 million m3. Its primary purpose was to supply the uranium mine at Trekkopje, located inland. The Trekkopje mine however never opened due to persistent low uranium prices, hence the plant has a contract to sell water to state-owned service provider Namwater and provides some of the water requirements for the town of Swakopmund. During the 2016 drought Areva offered to sell its plant to the Namibian government for US$200 million.
Water reuse Reuse of treated wastewater is practiced in Namibia in many urban areas such as Swakopmund, Walvis Bay, Tsumeb, Otjiwarongo, Okahandja, Mariental, Oranjemund and Windhoek. In most localities, water is reused for irrigation. In Windhoek, reclaimed water is also used for potable uses. Windhoek has been using recovered water for fifty years. Approximately 30% of the city's 400 000 residents' present drinking water supply is made up of reclaimed water. A representative example of direct potable reuse is the case of Windhoek (Namibia, New Goreangab Water Reclamation Plant (NGWRP)), where treated wastewater has been blended with drinking water for more than 45 years. It is based on the multiple treatment barriers concept (i.e. pre-ozonation, enhanced coagulation/dissolved air flotation/rapid sand filtration, and subsequent ozone, biological activated carbon/granular activated carbon, ultrafiltration (UF), chlorination) to reduce associated risks and improve the water quality. Since the year 1968 the capital of Namibia, Windhoek, has used reclaimed wastewater as one of their drinking water sources, which nowadays represent about 14% of the city's drinking water production. In 2001, the New Goreangab Reclamation Plant (NGWRP) was built by the City of Windhoek and it started to deliver drinking water in 2002 (about 21,000 m3 of water per day).
There is also a pilot project for small-scale reuse of treated wastewater in rural areas in Outapi in Northern Namibia as part of the CuveWaters research project. The wastewater of 1,500 people is collected in vacuum sewers and treated in such a way that pathogens are removed, but nutrients remain to a large extent in the water. The technology is relatively sophisticated for a rural area in a developing country, using upflow anaerobic sludge blanket digestion followed by aerobic treatment using a rotating biological contactor, a microsieve and ultraviolet disinfection. The water is then used to irrigate vegetables for the local market. Community members have been trained in how to operate the facilities and a tariff and billing system has been introduced to recover the operating costs of the plant from users.
Water use and access
Total water use in Namibia was estimated at 300 million m3 in 2000. The municipal sector including tourism and industry used 73 million m3 (24 percent), while the bulk of water use is for agriculture and livestock. Only 13 million m3 (4 percent) was used in mining at the time, although this amount has increased due to the development of mining – in particular uranium mining – after 2000. Mining in Namibia makes extensive use of water, which is used for a broad range of activities including in particular mineral processing, but also dust control, slurry transport and the water use of employees. Uranium mining uses large quantities of water for processing using alkali heap leaching. For example, the Trekkopje mine in the Namib desert uses 14 million m3/year of high-quality water that must be free of any salt. Saline water extracted through local wells is used for dust suppression, thus reducing the need for freshwater. Furthermore, some of the wastewater is treated and reused, thus further reducing water demand. Freshwater demand is met from the Erongo Desalination Plant that also supplies neighboring communities. Since the lifetime of the plant (30 years) is longer than the expected lifetime of the mine (12 years), already when the plant was planned it was expected that it would be taken over by NamWater at the closure of the mine.
The UN evaluated in 2011 that Namibia has improved its water access network significantly since independence in 1990. Furthermore, in rural areas access is sometimes limited by the long distance between residences and water points. As a result, many Namibians prefer the traditional wells over the available water points far away.
Water supply and water use in Windhoek