Dual flush discharge valve

The invention relates to a drain valve (2) for the realization of a two-flush with a full and einerTeilspulmenge in a device connected to a toilet cistern (96). This should have a particularly simple and space-saving design and also be particularly durable. According to the invention it is proposed to control the Teilspulmenge alone through a closable via a closing element subset bypass opening (46) which is arranged in the installed position on the water level of the Teilspulmenge, and an additional element as the closing element (10, 56, 78) form, with this subset bypass opening ( 46 may be) for controlling the open and closed Teilspulmenge (Fig. 1).