 Nuclear technology is helping scientists avoid another drought in Cape Town. Water scarcity is increasingly common in South Africa and elsewhere on the continent. In 2018, Cape Town was close to becoming the first major city in the world to run out of water. The city of four million people obtains its water supplies from dams filled by rainwater. When the dams went down to 20% and started getting lower, then the whole thing came to a critical point where we're talking about day zero scenario where people have to go stand in a queue to get water every day. South African experts are trying to better understand water resources by using nuclear science. Isotope hydrology is a really quick, easy tool that allows you to make some first order observations of how the groundwater system is behaving. By analysing water molecules, experts can determine source, movement and quality of water, even deep underground. This helps improve planning to avoid droughts. The results I hope will be useful for understanding the robustness of the groundwater system, to climate change, how sustainable is it, and therefore how viable is it to abstract large-gall groundwater to supplement the municipal network. The IAEA supports member states in managing their water resources in a more sustainable way.