It is important to adopt a common international understanding and perspective in the agreement on the environmental impact of agricultural water-use in the regions of the world. This paper investigates water-use sustainability as a measure of the impact on the environment and natural resources of irrigated paddy farming in 31 countries and regions of the world. A quantification theory was used to analyze the main simplified factors in water-use sustainability. A methodology and overall indicators for the evaluation on a national scale are proposed from an international comparison on water-use sustainability. The study provides a valuable insight into the international agreements on the relationship between agriculture and water resources.