Sri Lanka has an annual rainfall between 750 and 6,000 millimeters (mm), with large spatial and temporal variation. The availability of clean drinking water is a national imperative, but agriculture consumes the bulk of available water resources. Economic development, population pressure and rising demands from different sectors are placing increasing pressure on available water resources. With climate change threatening, there is a danger that the demand for water will outstrip supply - particularly in the Dry Zone of Sri Lanka where most irrigation schemes are located. This In Brief from the International Water Management Institute assesses the region's vulnerability to water shortage, and suggests where future investments could be made.