 Irrigation is the practice of applying water to crops, additional to rainfall. Irrigated agriculture has helped provide food supplies in areas which would otherwise not carry sufficient yields or cater to specific plants. Water in irrigation is commonly sourced from freshwater sources, which are groundwater aquifers and surface water bodies, such as rivers, lakes, springs and reservoirs. About 1.2 billion people already live in areas where water is physically scarce. When over-abstraction of water occurs, the rapid decrease in the amount of water affects the physical and chemical characteristics of water bodies and has severe effects on animals and human beings. Unfortunately, irrigation is often needed in areas of hot climate where water resources are scarce. There are three main approaches to increase the water use efficiency of irrigation. The first is to reduce water losses through managerial and technological responses, as almost 50% of abstracted water for irrigation is wasted from evaporation, leakage or spillage. A managerial response is irrigation scheduling, which reduces water losses by maximising irrigation efficiency and optimising water usage. An example would be night irrigation to avoid evaporation. A technological response is to improve the irrigation system. The commonly used irrigation methods today are surface irrigation like flood irrigation, sprinkler irrigation, drip irrigation and subsurface irrigation. Flood irrigation, the traditional method, was found to produce excessive evaporation and cause soil salinisation. Salinisation is a form of land degradation due to the accumulation of salt left in soil by the evaporated water. Policies recommended shifting to drip irrigation or subsurface irrigation, the most water efficient methods as they directly apply water to the areas needed by the crop. Another response would be to improve the water holding capacity of soils by increasing the amount of organic matter by adding animal or plant material to the soil. With healthier soils, the water holding capacity will improve and can support more plant growth and reduce the amount of irrigated water. Finally, crop selection plays an important role in water saving. Certain crops have the ability to take up water from deeper soil layers, like sorghum and sunflower. In Asia, some rice farmers now follow the method of SRI or System of Rice Intensification by using a different type of rice crop, which is more water efficient than the traditionally used one. Cosson, a water-intensive crop, is commonly grown in water-scarce areas but should be grown in more suitable regions. Certain crops used for biofuel, such as sugarcane, are also wasteful of water and should be avoided in water-scarce areas. The second approach is to use other water sources. Rainwater harvesting is the practice of collecting and storing water from rainfall to be used later on. This reduces the usage of water from freshwater sources. Similarly, water reuse is practiced to irrigate green areas in the city where wastewater is abundant. This is not recommended for food crop irrigation, as there are numerous health and safety hazards when using wastewater. Socio-economic responses, such as water monitoring and pricing, is the third approach. It seeks to improve water efficiency by raising awareness and giving incentives to farmers and water users. It is critical to know how much water is available and is used. As they say, you cannot manage what you don't measure.