Without water, there would have been no life on earth. That is a fact. But why is water so important for life? And for humans? During which activities do we use water? When you think about your own life, you will notice that there are many moments when you use water: showering, tooth brushing, making tea, going to the toilet, swimming, watering the plants etc. You need clean water for those activities. However, not much clean water can be found in the Netherlands. This chapter describes the process of purification and the way in which water is used for consumption and irrigation.