Abstract: A sprinkler system for plants and schrubs growing on the side of a hill has non-drain valves connected at discharge heads that are positioned at elevations below the main control valve for the system. The non-drain valves are opened by pressure of water exerted when the main control valve is opened. After the main control valve is closed and water pressure in the pipe system that feeds the discharge heads falls to a selected value, the non-drain valves automatically close, thereby preventing drainage from the discharge heads of water retained in the pipe system between the relatively low discharge heads and the relatively high control valve.