Close to the high-rise Ponte Towers in Johannesburg, researchers wrestle with the third piece in the drinking water treatment puzzle. If water is contaminated by microbes or inorganic materials, a municipal water treatment plant can purify the water to drinking standard. This way, bacteria, viruses and worm eggs are removed from water every day. Pollutants such as nitrates, phosphates and metals get similar short shrift.

But professors Bhekie Mamba and Rui Krause are focusing their nanotechnology research on detecting and eradicating organic pollutants, which are far more difficult to remove. Leaves, tanneries and poorly treated sewage are pollution water sources, but there are many others.