How much water do we really use? A case study of the city state of Singapore

The observed and predicted increase in urban population in the world is creating and will further create severe stress on existing water infrastructures and available water resources. Singapore's population has increased from about 1 million people in the 1950s to almost 5 million currently. The city state has invested massively in a sustainable water supply system, and is regarded by many as a role model for future cities with respect to this topic. Solutions like water reuse, desalination and water demand management have already been implemented. However, city dwellers use much more additional water in the form of virtual water. Their actual water footprint is much higher than only domestic water. Water required for the generation of agricultural and industrial products are imported to cities, and can put a heavy burden on water resources in surrounding and even distant (rural) regions. The city state provides a unique opportunity to analyse virtual water consumption for a city, as required statistical data are available through the national Department of Statistics. For other cities such detailed data are rarely available. Mostly these data are only provided on a national level. This analysis provides a quantification of the actual water use of a future city. The paper describes whether the consumption of agricultural products (in the sense of water for food) is also sustainable in Singapore. The agricultural products that contribute largely to the total water footprint of Singapore – wheat, rice, livestock products and cotton–are analysed and discussed in detail. A sustainable city of the future should account for its impacts beyond its borders. Whether the world can provide for the water and food for an increasing population highly depends on consumption patterns within future cities.