A country is said to be water stressed when the volume of reliable runoff falls below the amount of water withdrawn.

When the volume of reliable runoff, which is the amount of water that can be depended on to be available for use, falls below the amount of water withdrawn for different purposes like domestic, agricultural, and industrial, a country is considered water stressed. This means that there is not enough water to meet the demands of the population, leading to water scarcity and potential conflicts over limited water resources.