How a South African town cleaned up its polluted river using stones, wood and sand — SkimNews
Get the Energy newsletter
Daily energy & climate — solar, EVs, oil, the policy fights and tech bets shaping the transition. Free.
- University of Cape Town researchers built a nature-based filtration system using large stones, biochar (wood burned at 800°C), and smaller stones and sand to clean water from South Africa's Stiebeuel River, removing about 99% of toxins from 36,000 liters daily without chemicals.
- The Water Hub project in Langrug was established in 2018 but only this year reduced bacteria and pathogens to levels safe for irrigation, running off-grid on solar power from repurposed abandoned wastewater drying beds where water filters over five days.
- Langrug, an informal settlement near Stellenbosch in the Western Cape, grew from 3,000 to more than 26,000 residents without adequate sanitation infrastructure, driven largely by seasonal farm labor near wealthy Franschhoek.
- Kevin Winter, the UCT researcher leading the project, said treated water now irrigates food-producing gardens feeding the community, while most cleaned water is released back into the river to support surrounding ecosystems — about 3,000 liters daily is held back for irrigation.
- Winter framed the system as a food-security model for climate-stressed regions, citing the Western Cape's near-catastrophic 2018 drought that left reservoirs nearly dry, forced household water rationing, and cost roughly 31,000 farm workers their jobs.
- Winter said the filtration system is not designed to replace industrial-scale municipal treatment plants but can deliver clean irrigation water for rural communities lacking sewer infrastructure.
Why it matters: Langrug's population ballooned 8x without sanitation, and the Western Cape's 2018 drought cost roughly 31,000 farm jobs — so a zero-chemical, solar-powered system that scrubs 99% of toxins from 36,000 liters of sewage-laden river water daily, turning it into irrigation for community food gardens, gives climate-stressed rural settlements a replicable template for food security where municipal infrastructure has failed.
Ask SkimNews
