The hot and cold water mixing tap uses only one knob to set the temperature and the rate of flow. The body (F) is connected to the hot and cold water inlets (A1,A2). Admission of water to the mixing chamber is controlled by two springs (R1,R2) loaded poppet valves (W1,W2) the shanks (T1,T2) of which project into the mixing chamber. Circular sectors (S1,S2) pivoted at their outer ends in a fork (B) bear on the poppet valve shanks. The fork is carried on a screw (E) which is held in a ball (H) sealed (K) in the end of the body opposite the valves. A handle projects from the ball and can be swung from side to side or rotated. If the handle is rotated, the screw bears on the sectors which force open or allow the poppet valves to close. The fact that the sectors are pivoted at one end causes differential opening of the poppet valves, when the handle is swung from side to side, because of the different radii between contact points and ball centre.