Understanding how water recharges the West Coast Aquifer in South Africa is crucial for managing water resources. Scientists used isotopes to figure out where the water comes from and how long it stays in the aquifer. They found that different types of water have different origins, with some coming from rain and others from the sea. The age of the water suggests it was recharged during different climate conditions in the past. This information helped create a model of how water flows through the aquifer system.