with reference to the drawings , fig1 illustrates the overall valve assembly 10 attached to spout 11 of bottle 12 . the bottle contains liquid 13 and the invention has particular application to the five and six gallon water bottles used with liquid dispensing apparatus 14 . such apparatus typically involves an outer free standing cabinet 15 and an inner liquid holding container 16 . the inner container is bowl - shaped and includes sidewalls 17 extending from a bottom outlet wall 18 . when the bottle is inverted and lowered onto the cabinet , bottle shoulder 19 will rest upon an upper cabinet ring 20 ( fig5 ). spout 11 is sufficiently elongated so that it will extend centrally from the shoulder into at least the upper half of the container in order to prevent overflow . liquid will flow by gravity from the bottle into the container until the liquid level rises above the spout discharge outlet . this will then cut - off air to the bottle interior whereby further lowering of the bottle liquid level will create a vacuum thereabove . when the weight of the liquid in the bottle about equals atmospheric pressure , water will stop flowing from the bottle and overflow from the container will be avoided . as is conventional , spout 11 is provided with a standardsized discharge outlet 22 defined by a large annular bead 23 . generally , a protective cap seal is used to cover the outlet during bottle storage and delivery . prior to inversion of the bottle onto the dispensing apparatus , the cap seal is removed and replaced with the valve assembly of the present invention . the valve assembly includes valve housing 26 having an attachment means for releasable securement to the spout . as shown , the attachment means comprises an outwardly flared skirt flange 28 . the flange includes an inwardly curved peripheral end portion 29 that overlies and sealingly engages the annular bead 23 . the curved end portion conforms to a major part of the bead curvature and has a diameter slightly less than the bead circumference . preferably , it is constructed of a resilient material such as rubber or plastic . with the above characteristics , the skirt flange can stretch and firmly engage the bead in a releasable but sealable manner . depending on the type of bottle design being used , other equivalent attachment means such as cooperating threads , friction ribs , clamps and tapered plug structures may be utilized . the housing further includes a central aperture 30 which is in communication with outlet 22 . the aperture is defined by a sleeve - shaped housing sidewall having an inner wall surface 31 . an interior portion 32 of the aperture is enclosed by the housing and spout while an exterior portion 33 extends outwardly away from the spout . desirably , the aperture extends lengthwise relative to the spout with its center axis coextensive with the longitudinal axis of the spout . it is also preferable that the interior portion 32 have a diameter less than outlet 22 so that it may conveniently overlie and extend concentrically into the spout a short distance . the interior portion terminates at top edge 36 which presents a fiat ring - like surface . to facilitate initial filling of the inner container , exterior portion 33 is provided with one or more vent openings 34 through its wall thickness . the openings are located in close proximity to outlet 22 at base region 35 of the exterior portion . this arrangement helps insure that the desired liquid depth will be attained somewhat above the level that outlet 22 projects into the container ( fig4 ). mounted for axial movement within the central aperture is a valve means shown as plunger 40 . the plunger functions to control liquid flow from the bottle through the aperture . it entirely prevents such flow until the bottle spout is placed within the dispenser inner container . it then operates to open flow and permit filling of the container to a predetermined depth . with particular reference to fig3 the plunger comprises a head section 42 from which extends an actuator stem 56 . the head section includes an end plate 43 comprising a flat disc structure extending across interior aperture opening 44 . it may include a peripheral flange 45 that overlies and abuts against top edge 36 in the valve closed position . extending outwardly from the underside of end plate 43 is ring part 46 . the ring part comprises an annular - shaped wall structure having an outer surface 47 which conforms to the interior portion inner wall surface 31 &# 39 ;. when in a valve closed position , as shown in fig3 the ring part outer surface will form a sealing means and be in frictional engagement with the inner wall surface . to facilitate a firm but releasable sealing engagement , the surfaces may each have a slight corresponding inward taper . to insure the formation of an effective seal , or as a substitute to the above sealable mating surfaces , the sealing means of the invention may include a resilient sealing member . as shown , groove 49 is formed about the circumference of outer surface 47 . o - ring 50 is placed in the groove so that a portion of the o - ring will compress and seal against wall surface 31 &# 34 ;. as the interior portion unseats from the head section to an open position , as shown by arrows a in fig4 the o - ring will slide along the wall surface and decompress as it passes top edge 36 . either alone or in combination with one or both of the above , the sealing means may further comprehend the sealing engagement of peripheral flange 45 with top edge 36 . in such case , the flange underside and top edge should have flat mating surfaces . a gasket means therebetween , such as a rubber washer ( not shown ), may also be used to enhance sealability . the actuator stem of the valve means comprises upwardly extending opposing segments 57 , 57 of the ring part wall structure . each segment has a base portion 58 , 58 which comprises less than half the circumference of the wall structure . the circumference of each segment diminishes as each extends upwardly in a uniform and corresponding manner while maintaining the initial separation equal to the ring part diameter . when the segments approach their desired length , they curve inwardly and merge forming an actuation end 60 . the segments define an elongated open structure comprising opposing arcuate mirror - image sections with corresponding side edges 59 . the structure readily passes liquid and can also be manually grasped to move the head section in and out of engagement with the interior portion . also , since the segment spacing is maintained , the opposing segment outer wall surfaces will slide against the aperture sidewalls 31 . this action will serve to guide and facilitate stable axial movement of the actuator stem . when the head section is in a closed position , the actuation end will be at its outermost point a predetermined distance from the exterior aperture opening 62 . such distance should at least equal the axial distance required for unseating the head section from the interior portion . additional stem length adjustment may be required to insure that the actuator end will contact bottom wall 18 as the spout and valve assembly are lowered into the inner container 16 . unless the actuation end impinges the bottom wall before the bottle shoulder 19 engages cabinet ring 20 , the interior portion will not be moved away from head section 42 and allow liquid flow . to avoid the above circumstance and provide for universal application of the invention with a diversity of liquid dispensing apparatus , an abutment basket 70 is provided . as illustrated in fig6 the basket is utilized when inner container 16 &# 39 ; has an extended sidewall and greater depth . the basket comprises a bottom contact wall 71 from which extends an openwork sidewall 72 . the sidewall diverges upwardly and terminates with a dispenser engagement means . such means comprises a peripheral rolled edge 73 which engages cabinet ring 20 . the basket depth will correspond to the vertical distance required for contact with actuation end 60 and unseating of the head section 42 . when a bottle spout with valve assembly is lowered into the basket suspended within the container , end 60 will contact bottom wall 71 and allow for valve opening in the same manner as before . while the invention has been described with respect to preferred embodiments , it will be apparent to those skilled in the art that additional modifications may be made without departing from the scope and spirit of the invention . accordingly , it is to be understood that the invention is not to be limited by the specific illustrative embodiments , but only by the scope of the appended claims .