Panama has 0.1% of the fresh surface water in the world and an extensive hydrological network made up of 52 watersheds and 500 rivers. On the Atlantic slope, which occupies about 30% of the national territory, there are 18 watersheds with 150 rivers; the other 34 watersheds and 350 rivers are located on the Pacific slope. The greatest water demand is concentrated on the Pacific slope where 83% of the population lives and where more than 70% of economic activities are concentrated. Water availability is estimated at 119.5 km3/year, which corresponds to 31,521 m3/person/year for 2018. About 95% of the potable water in Panama comes from surface sources (rivers and lakes), while the remaining 5% comes from groundwater.