A container is provided having an open top end defining an access opening into an interior storage volume. A peripheral rim surrounds the access opening. A flexible membrane is sealed to the peripheral rim and a valve is attached to the membrane for venting gases from the interior of the container body. An overcap is provided to cover the access opening and be retained in the container rim adjacent the membrane. A bottom surface of the body of the overcap includes a continuous surface pattern thereon, with the surface pattern creating a plurality of gaps that define a continuous passageway along the bottom surface to the periphery of the overcap.
