A valve is disclosed, the valve comprising a housing having an first opening and a second opening, and an elastomeric member positioned in the housing, the elastomeric member comprising a thickness, a continuous peripheral wall projecting from the thickness, and a slit extending through the thickness, a continuous portion of the peripheral wall creating a continuous sealable contact with the housing and partitioning the housing into an upper section and a lower section, the elastomeric member configured such that upon creating a pressure differential between the upper section and the lower section of the housing causes either: (i) the peripheral wall to deflect from the housing permitting fluid flow around the elastomeric member; or (ii) the slit to open permitting fluid flow through the elastomeric member. Methods using the valve are also disclosed.