For obvious reasons, sewage is unappealing and drinking it, completely unfathomable. Yet, while most of the world is still debating if you should even try to treat household sewage to drinkable standards, Windhoek has been tapping water from it for decades.
In 2018, Namibians marked the 50th anniversary of the ﬁrst direct potable (drinking-quality standard) reuse plant in the world, the Goreangab Water Reclamation plant. In fact, it’s so successful, a second was kicked into action in 2002. The New Goreangab Reclamation Plant now puts improved water treatment technology into practice. In general though, there are three ways to tackle sewage treatment – all of which are becoming more common.
Different ways to tap from sewage
The first, is direct potable reuse. This is when sewage is treated to drinking-water standards and fed into the water distribution system. This is what is happening at Windhoek. The process has been taken up in other countries, including South Africa, where a water reclamation plant was constructed in Beaufort West.
The second is indirect potable reuse. Here, treated sewage is released back into natural systems like rivers to mix with water. Then, it is abstracted and treated to drinking standards. They do this in Singapore during droughts.
The last option is treated eﬄuent reuse. For this, sewage is treated, but not all the way to a quality that makes it fit for drinking. The water is then used for stuff like irrigation or industrial use. This is also happening in South Africa, both in Cape Town and in Durban.
The Durban Water Recycling Project (commissioned in 2001) treats eﬄuent and industrial wastewater to near drinking quality standards, and then sells it to industrial customers to use in manufacturing processes. The so-called sewage-to-clean-water plant can reportedly free up enough drinking water for about 300 000 people.
All three options can make a huge diﬀerence to the water security of a town, city, and country. Windhoek is a perfect example.
Why dry Windhoek looked to wastewater
Namibia, of which Windhoek is the capital, has the dubious distinction of the country with the lowest average rainfall in Southern Africa. Droughts are common, and in general, water is scarce. For decades already, all naturally available water sources in the centre of the country (where Windhoek is located) have been tapped to the max.
The city is committed to exploiting the maximum amount of water from all sources it has available. In Windhoek, every drop of water counts. Even the moisture in sewage cannot be allowed to go to waste.
A new water source is born
The reclamation plant was brought into operation in 1968, following severe water shortages before the extension of the state water supply scheme could be completed.
The plant is fed from two sources, the Gammams Sewage Treatment Plant and the Goreangab Dam. The plant can be split into two streams. One stream is to treat eﬄuent from the sewage treatment plant and the other for the treatment of Goreangab Dam water. The raw waters can also be blended and treated as a single stream.
Another serious drought in 1997 led to the construction of the second plant, to cater for the ever increasing demand for water. The new plant applies all the best practices and lessons from the first plant. This old one now treats water to irrigate parks and sports ﬁelds but, since it began in 1968, nobody in Windhoek has ever gotten sick because of the water it produced.
Still turning your nose up at sewage?
The treatment of wastewater to the point where we can drink it poses extraordinary challenges. Yet, Windhoek is living proof that it is possible and even necessary.
As more international examples of sewage reuse for diﬀerent purposes emerge, the case has already been made. With the correct technology and know how, our dirty water can be a new tap to help quench the thirst of cities of the future.
- I’ve not been to the Goreangab Water Reclamation plant, and only skipped through Windhoek on a mad road trip some years ago. Good photos of that reclamation plant turned out to be hard to come by, hence that photo of Windhoek I pulled from Wikimedia Commons, taken by mroszewski.
- This blog is part of an ongoing series tackling the problem of how we will live with less water. This is why we will have to. The first article looked at how cities developed, and what went wrong. The second, looked at how a new direction in how we develop the places we live can help solve our water problems (it’s an overview of Water Sensitive Urban Design and the concept of a ‘livable’ place). The third dug into the details of South Africa’s water crisis (it’s not a pretty picture). Then, we looked at the one thing that cities that need water MUST do.
- The whole movement of so-called water resilient cities started with stormwater. To be more precise, it started with sustainable drainage systems or SuDS.
- And, what about our dirty water? We can use that too, as this blog on Windhoek hows, but this blog will give you the details of what the potential in our dirty water really is
- None of this would have been possible without the support of the Water Research Commission (WRC) in South Africa. The mentioned blogs are excerpts from the book I wrote for them on Water Resilient Cities. If you don’t have a copy yet, get in touch, or leave a comment below. I’ll send you one (it’s free!)