It’s only a new water reuse technology in North America. Folks in Namibia, in southwestern Africa, have been using it to generate drinking water for half a century without any difficulties or problems. Not to mention the astronauts in space.
Windhoek, the capital of Namibia, is one of the world’s driest cities. Average rainfall is 250 mm per year but the heat evaporates so much of it that only 1% of rainwater infiltrates into the ground. The city’s water supply depends mainly on boreholes and three dams located 70, 90 and 160 km away.
Every drop of water counts is the motto of WINGOC, which manages a pioneering facility that has been producing drinking water from wastewater since 1968. People from other parts of the world – including drought-stricken parts of the US – have been coming here for years to learn from its progress in developing unconventional water sources.
Potable reuse safely turns wastewater into drinking water. Direct potable reuse (DPR), as in WIndhoek, introduces treated wastewater directly back into the existing water supply. It is safe, cheaper, quicker, and more efficient than many other options to sustain and expand water supply, and it has been gaining momentum as a legitimate, worthwhile, and potentially imperative solution to water supply problems in places other than Namibia. Another variant, indirect potable reuse (IPR), adds a step by introducing purified water into a groundwater aquifer, reservoir, or lake before introducing the blended water back into a water supply system.
The plant mimics nature to transform wastewater from Windhoek’s 350,000 residents into drinking water. “Everything is done biologically. The bacteria help digest the human waste and pull it out of the water, essentially mimicking what happens in nature but a whole lot faster,” says process engineer Justina Haihambo.
“The Goreangab plant has become an international benchmark, an innovative and sustainable water management model and an example of a successful public-private partnership that attracts experts from Australia, Singapore and the United States,” Pierre van Rensburg, head of Windhoek’s water department, said in 2018. “And if in the future the climate becomes even drier, recycling water will be even more important.”
The New Goreangab Water Reclamation Plant (NGWRP), the bigger DPR facility built in 2002 to meet the demands of an expanding capital city after Namibian independence in 1990, now produces up to 5.5m gallons of drinking water each day – up to 35% of the city’s consumption. The facility has never been linked to an outbreak of waterborne disease.
As water shortages grip the planet, Windhoek’s insights and experience are more important than ever. In recent years, delegations from the US, France, Germany, India, Australia, Singapore, and the United Arab Emirates have visited Windhoek seeking solutions to water shortages in their own countries.
Troy Walker, a water reuse practice leader at Hazen and Sawyer, which is helping Arizona to develop its DPR regulations, visited Windhoek last year. “[Windhoek] has helped drive a lot of discussion in industry,” he says. “[Innovation] doesn’t all have to come out of California or Texas.”
The First US DPR Facility
Back in 2002, when John Grant and his team in Big Spring, Texas, decided to build the first-ever direct potable reuse (DPR) facility in the US, they were just trying to provide safe, clean water for consumers in Odessa, Big Spring, Snyder and Midland during the region’s worst drought in decades. DPR was their only option.
By May 2013, the CRMWD opened a DPR plant that can treat up to 2 million gallons of wastewater effluent per day to drinking water standards. By June 2014, Wichita Falls opened the second US DPR plant, which can treat up to 10 million gallons per day. “Since we brought this treatment plant online, the feedback has been that the water tastes better than the lake water we were working with before,” said Daniel Nix, utilities operations manager for Wichita Falls.
The Clean Water Act, passed more than four decades ago, assisted indirectly in making a DPR facility possible, said Nix. “The Clean Water Act made changes to the way wastewater must be treated and turned into a very high quality water source. We sampled our wastewater effluent and compared it to 97 drinking water standards. With the exception of three components it was already up to drinking water standards before it was even treated.”
Despite the half century of use in Windhoek, however, DPR is legal in only three US states – Texas, Arizona (on a case by case basis) and Colorado, as explained in a long and detailed recent analysis in Resilience that is worthwhile reading if you want to know more. But it is catching on. (There are now IPR facilities in Arizona, Texas, and California, the article notes, and a dozen states have developed regulations for the process.)
Maynilad’s New Water Treatment Plant
In 2023, a first-of-its-kind project in the Philippines was touted as the “Water Reuse Project of the Year” at the Global Water Awards in Berlin, besting internationally known companies from the US, Australia and SIngapore. Maynilad Water Services’ Parañaque New Water Treatment Plant receives treated used water from a sewage treatment plant and converts it into drinkable water supply that meets the 2017 Philippine National Standards for Drinking Water.
In the US, El Paso Water is building a DPR facility that will turn up to 10m gallons of wastewater per day into purified drinking water – twice as much as Windhoek, according to a recent Positive News article. “This facility is the game changer in the nation’s efforts to secure safe and reliable water supply for ratepayers throughout the West and nationwide,” says Pat Sinicropi, executive director of the WateRuse Association. But WIndhoek will always have been the first.
Is Wastewater an Answer for Adapting to Climate Change? Resilience, Aug. 30, 2023
Why everybody wants to drink like Namibians. Positive News, Aug. 30, 2023
Texas leads the way with first direct potable reuse facilities in U.S. Water Online, Sep. 16, 2014
Cover image: New Goreangab Water Reclamation Plant, Windhoek, Namibia