Effective water planning requires an understanding of current water demands and supplies, as well as a recognition of the uncertainties around both in the future. For example, on the supply side, climate change can affect both the wet and dry seasons, the frequency and duration of extreme events, and the water requirements with higher temperatures. On the demand side, there can be demographic, economic and political shifts that can be quite unpredictable. The challenge is to find the best path forward with the current knowledge at hand, obtain data that are crucial to know better going forward, and take actions – both in the form of policy and infrastructure development – that ensure the highest level of water security that is equitable and sustainable.