Abstract: An adjustable height fill valve for controlling the water level in a storage tank for a toilet includes a riser mounted in the tank and connected to a pressurized water supply. The riser includes an anti-siphon body telescopically mounted over a fixed shank. The anti-siphon body telescopically adjusts between retracted and extended positions. A pilot valve is mounted on the anti-siphon body in fluid communication with the water supply. A float is mounted in association with the pilot valve to selectively open or close the pilot valve depending on the water level in the tank. A latch on the anti-siphon body and a series of stops on the shank are releasably engageable to adjustably fix the position of the body on the shank between the retracted and extended positions. The stops comprise first and second sets of axially spaced and interleaved fingers which define a serpentine track into which the latch extends.