Water footprint is a new index for water resources, which can discover the water resources utilization more accurately. The calculation of water footprint in a regional level is helpful for a better understanding of water quality and water quantity. In this chapter, the concept of water footprint and its calculation method as well as application are introduced. The water footprint of Shanghai is discussed, including the water consumption, sewerage, industrial water utilization and discharge. It is suggested that water footprint should be adopted as a tool for water resources management in Shanghai. Water utilization efficiency and water risk management are also highlighted. Pollution monitoring and control for typical industrial sectors are vital for the improvement of water quality in Shanghai. Chongming Island is used as a sample for the calculation of virtual water and water footprint. The water footprint of agriculture in Chongming Island is calculated. Based on the investigation and analysis, it is found that the water quality of city level is better than that of county level, while the water quality in the town and village level is worse than that of the county level. The water resources in Chongming Island are abundant. The water footprint of Chongming Island is characterized by the fact that agricultural water footprint is the main part. The proportion of agricultural water footprint in Chongming Island is greater than that of Yangtze River. The structure of agriculture and agricultural products export are important for the water footprint of Chongming Island. <<