Sustainable water supply means to find reliable and resilient approaches to various human needs for water for that does neither exhaust the water sources and the local economy nor have long term negative impact on the environment. Agriculture consume about 70% of the current world water supply, whereas domestic and industrial use is about 8% and 22% respectively (WBCSD 2009). Read more about the water cycle here. This course focuses on domestic water supply. Potable water for domestic use is normally derived from surface or groundwater sources or from rainwater harvesting (RWH). Other sources are harvesting of fog or air moisture, bottled water or even melting of snow or ice or sea water desalination. Methods for desalination of seawater have improved, but are still requiring substantial energy input and are thus not sustainable from an energy perspective. This module will mainly focus on ground- or surface-water sources and RWH and give the student knowledge that aids selection and design of sustainable water supply options in different parts of the world including crisis situations (disaster situations will be discussed in Module 6). Cases are used to illustrate different water supply and treatment options and to motivate the learning process.