A wet cup drinker for birds has vertical inlet tube (1) with an inlet (10) at the top and carrying a trough (3) at the bottom. A horizontal tube (12) branches from the vertical tube and has its outer end closed by a wall having an aperture (25) through which passes a closure member (15). An open-bottomed float (29) surrounds and slides on the vertical tube (1) and has on its inner periphery a cam surface (36) which engages a cam follower surface (18) on the valve closure member (15). The water level in the trough is maintained approximately constant.