Squeeze bottle with valve septum

A spill-proof squeeze bottle liquid dispenser comprising:

• a liquid container having an outlet opening to the exterior of said container and a resiliently flexible wall adapted to be deflected inwardly to expel liquid from the container through said outlet and then released for elastic strain energy return to its normal shape with resultant air inflow to the container through said outlet;
• a septum of relatively thin resiliently flexible material spanning said outlet and containing a substantially 90.degree. butt cut slit formation defining a resiliently flexible tongue-like valve flap integrally joined along a hinge line area to the septum proper for outward and inward deflection of said flap from the plane of said septum to provide a liquid flow opening through said septum complemented by said flap;
• said valve flap having a closed normal unstressed position within said septum liquid flow opening substantially coplanar with the septum wherein the flap complements and seals said liquid flow opening against liquid passage therethrough, whereby said flap is deflected outwardly from said normal position by internal liquid pressure when said container wall is deflected inwardly to permit expulsion of liquid from the container through said outlet, and said flap is returned to its normal position by elastic strain energy to block passage of liquid from the container through said outlet upon equalization of the internal container pressure and ambient air pressure;
• and an air flow opening in said septum of a cross-sectional area that is porous with respect to the passage of air and non-porous with respect to the passage of the contained liquid.