This chapter discusses water supply systems used by firefighters. It covers the different types of water sources and supply systems, including underground piping and storage tanks. It also describes the valves used to control water flow and the different types of fire hydrants, their locations, and how to inspect and operate them. Alternative water supply methods for rural areas are discussed, such as water shuttles using portable tanks and relay pumping from nearby sources. The chapter emphasizes the importance of firefighters understanding local water supply systems and how to access water for firefighting.