A mixer tap assembly is shown which has a mixing chamber for mixing fluids from two inputs, and a mix controller to control the ratio of fluid flow into the mixing chamber from the inputs. The mix controller includes a mix actuator which operates a mix control apparatus, such as a rotatable sleeve, which is connected to a mix valve apparatus associated with the mixing chamber. The mix actuator and a fluid outlet are mountable on or above a work surface via a mounting apparatus, while the mixing chamber is mountable below the work surface. Furthermore, the mix control apparatus and an output conduit, between the fluid outlet and the mixing chamber, pass through a bore in the mounting means, so minimizing the footprint of the mixer tap assembly on the work surface.