What This Chapter Shows: Water is unique from an ecosystem perspective because water and the associated freshwater systems are linked to all four categories of ecosystem services. This chapter provides an overview of water availability and demand, and describes where in Kenya specific water uses are concentrated. A first set of maps shows the uneven availability of surface water as exemplified by annual and seasonal rainfall, as well as the network of permanent and intermittent rivers. The next map compares water availability to projected demand from households, industry, and agriculture and highlights where demand is projected to exceed local surface and groundwater supplies. The following section presents a series of maps reflecting the main uses and users of water in Kenya: sources of drinking water supply across the country, water transfers to Kenya’s two largest urban areas, subdrainage areas important for electricity generation, location of irrigated crop production, and water demand from livestock and wildlife in the rangelands. Two maps showing the occurrence of floods conclude this chapter. They serve as a reminder that impacts from ecosystem processes are not always benign: what constitutes a service for one group or area may be very detrimental to another group or area. Summing Up: From an ecosystem standpoint, water is unique, in that it is linked to all four categories of ecosystem services. Provisioning services include: the storage and retention of water in lakes, rivers, and as groundwater; water as an input to grow food, timber, fiber, and fuel; and freshwater for direct consumption. Regulating services of freshwater systems and important freshwater habitats (e.g. wetlands) include modifying water flows, recharging and discharging groundwater resources, and diluting or removing pollutants. Supporting services include nutrient cycling, soil formation, soil loss, and promoting biodiversity. Cultural services include recreational benefits, as well as the spiritual and inspirational roles of water bodies and aquatic habitats.