Abstract: Disclosed is a liquid metering valve unit, particularly for water. The unit uses a dash-pot mechanism filled with metering liquid such as water, silicone oil or a mixture of water and glycerine. The dash-pot mechanism is a closed system. The unit comprises a sleeve member having an axial bore and a transverse bore communicating with the axial bore. One end of the axial bore connects to a liquid supply and the transverse bore connects to an outlet. A valve stem in the axial bore is slidable between an open position and a closed position in which a resilient seat washer seals the end of the axial bore. A spring biasses the stem toward the closed position and the stem can be manually moved to the open position. Movement of the stem to the closed position is controlled by a dash-pot mechanism or regulating means comprising a cup washer secured to the stem and disposed within a liquid-filled chamber betwen the stem and sleeve.