South African town cleans polluted river for irrigation using natural filtration

The project, known as the Water Hub, uses stones, heat-treated wood biochar, and sand to purify 36,000 liters of water daily. This water, previously contaminated with sewage, chemicals, and drug traces, is now clean enough for irrigating community vegetable plots, addressing food security in the rapidly expanding informal settlement. The system, established in 2018, has successfully reduced bacteria and pathogens by approximately 99%, making the water suitable for irrigation, though not for drinking.

It operates off-grid using solar power to pump water through a network of filtration cells over five days. Kevin Winter, one of the researchers, highlights the system's potential as a model for rural communities, especially in the face of climate change challenges like prolonged droughts and water scarcity, which significantly impacted the Western Cape in 2018.