a liquid dispenser bottle of a resiliently flexible material has a relatively thin , resiliently flexible septum of circular planform seated on and spanning the dispenser outlet , peripherally sealingly clamped in place by a dispenser nozzle cap . the septum has a 90 ° butt cut slit formation defining at least one resiliently flexible valve flap integrally joined along a hinge line area to the septum proper for outward deflection of the flap by internal liquid pressure when the dispenser is squeezed . the septum is also formed with at least one tiny hole , preferably on or in the vicinity of the hinge line area to increase flexibility of the valve flap , to serve as a vent to greatly accellerate relaxation and normalization of the squeeze bottle wall .