A fresh and dependable supply of water is critical to sustaining life and supporting healthy communities, economies and environments. In every city there are two broad water issues (Figure 11.1 ): water supply and water quality, both of which rely on water infrastructure. In the case of water supply, water infrastructure includes the systems of delivery (aqueducts, pipes). Water quality is an issue associated with pollution and the removal of contaminated or dirty water. Here, water infrastructure includes sewerage systems and treatment facilities. In this chapter we examine both supply and quality issues. We will first consider these water issues in developed cities, with a particular focus on US cities. Then we will examine these issues in developing cities.