The difference between physical and economic water scarcity

Source

What is interesting about this map, is that it divides water scarcity in physical and economic scarcity. In areas of physical water scarcity there really is just not enough water available. 

But with economic water scarcity the situation is different: "Economic scarcity is where there is enough in-country water, but heavy investment needs to be made to ensure there will be no eventual physical water scarcity" (WWF Global), This applies for most countries in Central Africa.