Distribution mains are the pipelines that make up the distribution system. Their function is to carry water from the water source or treatment works to users. Arterial mains are distribution mains of large size. They are interconnected with smaller distribution mains to form a complete gridiron system. Typical distribution system layout.
Storage reservoirs are structures used to store water.
They also equalize the supply or pressure in the distribution system. A common example of a storage reservoir is an aboveground water storage tank. Booster stations are used to increase water pressure from storage tanks for low-pressure mains. Valves control the flow of water in the distribution system by isolating areas for repair or by regulating system flow or pressure. Hydrants are designed to allow water from the distribution system to be used for fire-fighting purposes.