What is the role of a drain valve at the end of an irrigation system?

The role of a drain valve at the end of an irrigation system is indeed to facilitate water drainage after operation. A drain valve allows for the controlled release of any remaining water in the system, which can prevent water from remaining stagnant within the pipes or other components. This is particularly important for systems that may be subject to freezing temperatures, as it minimizes the risk of damage from ice formation. Additionally, proper drainage helps maintain the longevity and efficiency of the irrigation system by reducing the buildup of sediments and pathogens that could affect the water quality.

The other options refer to different functions or misconceptions about the role of various components in an irrigation system. For instance, increasing water pressure or controlling emitter flow pertains to different parts of the irrigation setup, such as pressure regulators or flow control valves, rather than the drainage functionality addressed by the drain valve. Ensuring a continuous water supply usually relates to the pump or source of the water, not to the drainage aspect that the drain valve serves.