A closer look at Windhoek’s water
“Water is the driving force of all of nature,” Leonardo da Vinci said. No truer word has been spoken.
Water is essential for every human being, be it for cleaning, cooking and - importantly - drinking.
But how does water get to residents of Windhoek? And where does it come from?
A water requirement of 24.4 million cubic meters (m³) is currently needed for the capital. In addition, Windhoek groundwater is to be artificially recharged by 2.8 million m³. This equals a total of 27.2 million m³ (1 cubic meter = 1 000 litres) for the city in 2021/2022.
Windhoek’s water is secured via three supply sources: The bulk – a total of 77% last year – is supplied by NamWater; then the Windhoek Goreangab Operating Company (WINGOC) recovers and supplies drinking water from treated wastewater, which accounted for around 21% of the water supply in 2021; and the third water source is the Windhoek aquifer – production wells that help supplement water for the city during emergencies such as a particularly severe drought.
The aquifer contributed 2% to Windhoek's water supply last year.
Why is access to groundwater so important, given that it is a finite resource?
But first a little background: The first drilling to access the aquifer began as early as the 1900s. At the time, Windhoek was growing rapidly and the demand had to be met somehow. The first state water supply system was inaugurated in 1911.
The Windhoek aquifer is an underground, natural structure that contains groundwater. The aquifer naturally fills with approximately 1.73 million m³ of rainwater a year.
When NamWater’s water supply is limited, the aquifer is used extensively to support the city’s water supply. This is especially in times of drought when there is little or no water in dams. However, since the city already outgrew the capacity of the other water supplies in 2012, more and more groundwater needs to be accessed.
To get to the water, deep holes are drilled, reaching up to 500m below the surface. These boreholes are equipped with pumps and pipelines up to 250m below the earth’s surface. When the aquifer is accessed, water consumption exceeds the natural replenishment from rainwater; if no action is taken, the Windhoek aquifer would quickly dry up and could no longer be used.
In a bid to extend the life and use of Windhoek’s groundwater, a process called “Managed Aquifer Recharge” (MAR) was introduced. Through this process, water is pumped (back) into the aquifer and in a controlled manner, which is then stored underground for future use. This also extends the possibilities of using the aquifer and increases its potential. The water is then pumped to the groundwater when the dams or surface water sources have particularly high water levels.
In addition to the aquifer, other emergency solutions have been and are still being developed by NamWater in the central north of the country, which can be used in times of limited water availability. However, this supply option relies on the natural replenishment of groundwater through precipitation.
What are the alternatives?
Both the aquifer and these emergency sources can only be used for a limited time. According to the City of Windhoek's Department of Infrastructure, Water and Technical Services, government is currently looking at a permanent solution for a reliable water source for the central areas of Namibia. These include sources in the far north, perennial rivers, as well as water from the coast or even from the far south, for example from the Neckertal dam.
However, these are all long-term projects that would probably take 8 to 10 years from approval to implementation. In addition, it is also extremely costly.
Until better and, above all, long-term solutions are put in place, Windhoek will have to continue relying on the three sources mentioned above. This is another reason why Windhoek’s groundwater levels must be kept as high as possible and to keep recharging aquifers.
Between March 2020 and March 2022, the groundwater level rose by an average of 50 meters. This is thanks to both the rain and the MAR method. In addition to the natural replenishment of 1.73 million m³, from 10 May 2021 to 11 April 2022, 2,269,659 million m³ of water was artificially added to the Windhoek aquifer through boreholes. The annual target for aquifer injection by artificial recharge is currently 2.8 million m³.
Given the above, it is obvious that water should not be wasted in Windhoek, no matter what the season. In a bid to save as much water as possible, the municipality has various tips on how you can and should save water in everyday life:
• Check your water levels regularly and see if there are leaks somewhere. You can test this by reading the water level and then not using water for about six hours. If the level changes in the six hours, there must be a leak somewhere. Try to isolate it immediately!
• Keep your lawn as small as possible. If you own a real lawn, a proper sprinkler system will increase the efficiency of garden irrigation and save water. If you have plants in the garden, they should be robust and indigenous. Try to water them only once a week or twice a month. Swimming pools should be covered and only filled when absolutely necessary.
• In the bathroom, water-saving toilets are helpful. Also, rather take a short shower instead of soaking in the bathtub.
Finally, Namibia had reasonably good water levels this year. Nevertheless, we cannot rest on our laurels, because it is difficult to predict when the next severe drought will hit us.