Abstract:
An automatic filter shutoff device containing a filter, removably connected to a water container and in fluid communication with a water dispenser, the device monitors water dispensing and disables dispensing after a predetermined amount of water usage. The monitoring and disabling mechanism has a shutoff moveable between dispensing and disabling locations. The disabling location being one in which the mechanism is placed in an interfering position with the connection between the device and the water container. The mechanism automatically moves into the disabling location after the predetermined amount of water usage has occurred without interrupting water dispensing from the then connected water container. This requires that the used filter shutoff device be replaced in order to reestablish connection to a successive water container.

Description:
This is a continuation of application Ser. No. 09/618,711, filed Jul. 18, 2000, which is as U.S. Pat. No. 6,354,344, on Mar. 12, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to the dispensing of filtered, bottled water. More specifically, the invention relates to a shutoff device that monitors the number of bottles used and then disables further use of the filter when the filter has reached the end of its useful life. The device can also provide an early warning signal to the user that the filter is nearing the end of its useful life. 
     Self-contained filters for removing unwanted minerals and chemicals such as chlorine have become increasingly popular with bottled water users. These filters may be threadably attached or otherwise connected to the opening of a bottled water container, or may be contained within the water dispenser unit. Various devices are also known for monitoring water flow and then interrupting water flow after a predetermined use. 
     Some prior art devices have provided techniques for opening a pressure vessel containing a carbon filter used in water purification. However, such techniques are cumbersome and undesirable for the user. Thus, it is desirable to provide an economical self-contained dispenser shutoff and filter cartridge which may be easily replaced when a monitor indicates that the filter has reached the end of its useful life. 
     In general, prior art patents and known water dispensing disabling devices (herein termed “shutoff devices”) with a filter have tended to concentrate on ways of interrupting water flow through the bottle opening once the filter has reached the end of its useful life, by physically blocking water flow. However, this may result in an interruption in dispensing when the water container still has a substantial volume of water in it, which is not desirable from a user viewpoint. To overcome this problem, some prior art devices provide specific shutoff mechanisms so that when the filter cartridge is removed, dispensing is stopped; these devices also require a separate filter monitor device to visually or audibly warn the user that the filter has reached the end of its useful life. Many such shutoff devices have also tended to have a number of moving parts, increasing the risk of part malfunction. 
     However, there is a need for a water filter shutoff device which monitors water usage and automatically disables dispensing when the filter has reached the end of its useful life, without the need to rely on visual or audible warning signals. Such a filter shutoff device would also preferably meet the following constraints. Given space constraints, the shutoff device preferably is integral with the filter, and should not unduly impede flow through the filter. The shutoff device would also preferably allow presetting at the time of manufacture to change the allowable water flow or application uses, so that the device could be used with differently rated filters and differently sized water containers. The device should be economical to manufacture and preferably not require an entirely new mold or any substantial additional investment in assembly equipment or fixtures, while also being relatively simple in design with few moving parts to reduce quality control risks. The shutoff device would also preferably disable dispensing, without interrupting water flow from the currently used water container, when a monitor indicates the useful life of the filter is over. 
     A filter shutoff device preferably meets NSF criteria, including qualifying as a filter “performance indication device” (PID) under NSF standards, and include component materials that have existing NSF approval for extraction. If no filter monitor/PID is provided for a water dispenser with a filter, obtaining NSF approval currently requires that the filter be tested to work at 200% of its rated capacity. If a PID is provided, the filter need only be tested to work at 120% of its rated capacity for NSF approval. For example, if a filter is rated for 150 gallons, and a filter PID is provided, the filter need only have a capacity of 180 gallons, as opposed to 300 gallons if no filter PID is provided. This is a significant added cost feature for a filter manufacturer, since providing a filter capable of filtering 300 gallons requires additional media content resulting in a significant added cost. 
     Filter shutoff devices must also be provided with venting in some manner to allow continuous water flow, without “lock up”. One problem with such devices is that, upon initial use, as water from the inverted water bottle flows into the device, water pressure/water hammer conditions may cause unfiltered water to leak or spurt out of the venting channels and into the dispensing unit. A sufficient volume of water may escape filtration in this manner, such that the device may not receive NSF approval for, e.g., lead testing. It is also desirable to provide a filter shutoff device which overcomes this problem. 
     Accordingly, an object of the present invention is to provide a shutoff device integral with a filter and useable with a water dispenser, in which the water dispenser is automatically disabled at the end of the useful life of the filter. 
     Another object of the invention is to provide a filter shutoff device which does not impede or interrupt water flow between the water dispensing device and a water source such as an inverted water bottle. A further object is to provide such a device that qualifies as filter PID under NSF standards, enabling the more economical manufacture of the filter. 
     Yet another object is to provide a filter shutoff device which may be manufactured in an economical manner, such that the device monitors the number of water containers used, disables further dispensing after a predetermined number of uses, and then may be discarded and replaced with a new device. 
     A further object is to provide a filter shutoff device which automatically disables the connection between the device and a water container, rather than simply providing a visual indication of end of filter life, and rather than maintaining the ability to make this connection and physically impeding or interrupting water flow. 
     A still further object is to provide such a device with an appropriate size and configuration, together with appropriately located and sized vent holes, to ensure that unfiltered water does not leak out of the device and be dispensed. 
     DEFINITION OF CLAIM TERMS 
     The following terms are used in the claims of the patent as filed and are intended to have their broadest meaning consistent with the requirements of law. Where alternative meanings are possible, the broadest meaning is intended. All words used in the claims are intended to be used in the normal, customary usage of grammar and the English language. 
     “Automatic filter shutoff device” means a device in fluid communication with a water container which filters water and then interferes with the ability to dispense water from the container after a predetermined amount of water usage (i.e., the “shutoff” feature), which may generally correspond to the useable life of the filter, has been reached. “Automatic” in this context means that shutoff occurs without the need for user intervention, such as without the need for the user to respond to a visual or audible signal from a filter monitor. 
     “Monitoring and disabling mechanism” means a mechanism which monitors filter life by monitoring water usage, and which includes a shutoff feature. 
     SUMMARY OF THE INVENTION 
     The objects mentioned above, as well as other objects, are solved by the present invention, which overcomes disadvantages of prior filter shutoff devices for water dispensers, while providing new advantages not believed associated with such devices. 
     In one preferred embodiment, An automatic filter shutoff device is provided, and is removably connected to a water container and in fluid communication with a water dispenser. The device is adapted to monitor water dispensing and disable dispensing after a predetermined amount of water usage. The device includes a housing containing a water filter and removably connected to the water container; and a monitoring and disabling mechanism having a shutoff apparatus moveable between first and second locations, the first location being one in which water dispensing is monitored by the mechanism, and the second location being one in which the mechanism is placed in an interfering position with the connection between the housing and the water container. The shutoff apparatus automatically moves into the second location after the predetermined amount of water usage has occurred, and without interrupting water dispensing from the then-connected water container, so that the used filter shutoff device must be replaced in order to reestablish connection to a successive water container. Preferably, the predetermined amount of water usage generally corresponds to the useable life of the filter. 
     In a preferred embodiment, the filter shutoff device is adjustable so that dispensing may be disabled after differing amounts of water usage. In one preferred embodiment, the shutoff apparatus includes a plunger whose vertical height may be varied, and the second location is one in which the plunger obstructs the connection of the filter housing and the water container. The monitoring and disabling mechanism may include a filter cap with a downwardly depending leg having a locking window engageable with a locking tab located on the shutoff apparatus. The engaging surfaces of the locking tab and locking window may be angled to facilitate entry of the tab within the window, and to prevent disengagement of the tab and window. 
     In a particularly preferred embodiment, the plunger has a top surface with a throat opening and annular side walls with spaced openings, and wherein the surface area of the orifice is approximately equal to the surface area of the side openings. 
     The monitoring and disabling mechanism may include a filter cap mounting radially disposed, opposing teeth, and the shutoff apparatus may include a rotary indexer having a radially protruding tab iteratively communicating with the teeth. In this embodiment, the rotary indexer monitors water dispensing by tracking the number of water containers used during dispensing Preferably, the monitoring and disabling mechanism is a NSF-compliant performance indication device. 
     A visual indicator, such as a color band located on an outer surface of the filtering and disabling mechanism, may be provided to warn the user that the filter is nearing the end of its useful life. The monitoring and disabling mechanism may also include a visual indication to facilitate adjusting of the mechanism for differing water usages. 
     In an alternative embodiment, the monitoring and disabling mechanism may include a helical-shaped spring, and a rotary index engageable with teeth having a number corresponding to the predetermined amount of water usage. 
     In another aspect of the invention, a filter mechanism is provided which is connected to a bottled water container and adapted to be inverted and placed in fluid communication with a water dispenser. The filter mechanism includes a housing containing a water filter with a throat removably connected to the bottled water container. The throat is a restricted orifice sized, such as less than one inch or about ¾-inches in diameter, for example, to permit a volumetric flow rate of not greater than about 7,500 ml./min. of water passage during inversion of the water container and initial flow from the container into the filter. A plurality of vent holes located in an upper surface of the filter housing are provided; the vent holes are sized to permit air from the filter to escape into the water container and allow continuous water flow from the container into the filter. When a new water container is connected to the housing, the water level within the filter does not reach the vent holes in the filter housing. This embodiment may, but need not, including a monitoring and disabling mechanism having a shutoff apparatus as described above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the invention are set forth in the appended claims. The invention itself, however, together with further objects and attendant advantages thereof, will be best understood by reference to the following description taken in connection with the accompanying drawings. The drawings illustrate one preferred embodiment of the present invention. As further explained below, it will be understood that other embodiments, not shown in the drawings, also fall within the spirit and scope of the invention. 
     FIG. 1 is a perspective view of a water bottle being filled, together with one preferred embodiment of a filter shutoff device according to the present invention; 
     FIG. 2 is a perspective view showing the threaded connection of a preferred embodiment of the filter shutoff device according to the present invention to a water bottle; 
     FIG. 3 is a perspective view showing the filter shutoff device, now attached to the water bottle, just prior to seating onto the upper housing of a water dispenser; 
     FIG. 4 is a perspective view showing various components of a preferred filter shutoff device according to the present invention; 
     FIG. 5 is a perspective view of the preferred, assembled filter shutoff device; 
     FIG. 6 is a top view of FIG. 5; 
     FIG. 7 is a sectional view along reference line  7 — 7  of FIG. 6; 
     FIG. 8 is a side and planar perspective view of a preferred form of the plunger component of the filter shutoff device; 
     FIG. 9 is a side and planar perspective view of the plunger and a partial cross-sectional view of the filter cap;: 
     FIG. 10 is a side and planar partial, cross-sectional view of the plunger and filter cap; 
     FIG. 11 is a side and planar partial, cross-sectional view of the plunger, filter cap and filter housing; 
     FIG. 12 is a side and planar perspective view of the plunger, filter cap, spring and filter housing; 
     FIG. 13 is a side and bottom perspective view of the lower portions of the plunger and filter cap; 
     FIG. 14 is an exploded view of the area circled “ 14 ” in FIG. 13; 
     FIG. 15 is a side cross-sectional view of the preferred assembled filter shutoff device; 
     FIG. 16 is an exploded view of the locking mechanism of the preferred filter shutoff device; 
     FIG. 17 is a side cross-sectional view of an alternative embodiment of the filter shutoff device of the present invention; 
     FIGS. 18 and 19 are partial, side cross-sectional views showing two positions of the locking mechanism of an alternative filter shutoff embodiment; 
     FIG. 20 is a side and planar cross-sectional view of the alternative filter shutoff embodiment of FIG. 17; 
     FIG. 21 is a side and planar perspective view of the monitoring and shutoff components of the alternative filter shutoff device of FIG. 17; 
     FIG. 22 is a side and planar perspective view of the assembled components shown in FIG. 21; 
     FIGS. 23-25 are side; enlarged views of the FIG. 17 embodiment showing opposed teeth and their interaction with a tab of the alternative filter shutoff device; 
     FIG. 26 is a partial side and cross-sectional view of an alternative, one-piece embodiment of the filter shutoff device of the present invention; 
     FIG. 27 is a partial sectional,view along reference line  27 / 27  of FIGURE 26; 
     FIG. 28 is a sectional view along reference line  28 / 28  of FIG. 26; and 
     FIG. 29 is an exploded view of a portion of filter cap  80  of FIG.  10 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Set forth below is a description of what are currently believed to be the preferred embodiments and/or best examples of the invention claimed. Future and present alternatives and modifications to these preferred embodiments are contemplated. Any alternatives or modifications which make insubstantial changes in function, in purpose, in structure or in result are intended to be covered by the claims of this patent. 
     Referring first to FIGS. 1-3, a water container such as water bottle  20  is shown, together with a preferred embodiment of the filter shutoff device of the present invention, generally referred to as  30 . While it is preferred that water bottle  20  have threads  35  that allow threaded connection with mating threads  25  on the neck of water bottle  20 , a threaded connection is not required. 
     Referring to FIG. 3, filter shutoff device  30  is sized and shaped to permit its placement within opening  27  of water cooler housing  26 . (The particular water dispenser chosen for use is of little importance to the present invention.) For this purpose, filter device  30  may include an enlarged rim or neck  37  that rests on the top peripheral wall  27   a  of aperture  27 . 
     Referring now to FIGS. 4-6, one preferred embodiment of filter device  30  includes the following components: filter cap  80 ; plunger  90 ; spring  57 ; support or media retaining ring  33 ; and upper and lower filter pads  32   a ,  32   b . Upper pad  32   a  is preferably sonic-welded to ring  33 , inside rim  33   a ; lower pad  32   b  is preferably sonic-welded to the lower interior of filter housing  36 . Pads  32   a ,  32   b  maintain the filter media, such as activated charcoal  64 , in place within filter housing  36 . During assembly, plunger  90  is placed down through within center opening  92   a  of plunger  90 . Spring  57  compresses against plunger  90  and, in turn, is compressed by retaining ring  33 ; compression is maintained on plunger  90  for the reasons described below. Filter cap  80  may be sonic-welded to the upper surface of filter housing  36  since, in the preferred embodiment, filter shutoff  30  is designed to be replaced, rather than cleaned and re-used, when the useful life of the filter is over. Filter housing  36  is preferably generally cylindrical in shape, as shown, and includes passages  38  (FIG. 11) in its lower surface which permit water passage through the lower end of filter housing  36 . Ribs  113  on the outer surface of housing  36  facilitate gripping of the housing by the user. Filter cap  80  includes vent holes  120  which, in the preferred embodiment shown, are six in number. 
     Referring to FIG. 8, a preferred from of plunger  90  includes an annular top surface  92  with a restricted throat opening  92   a . Legs  93  project downwardly from top surface  92  and include projections  93   b  and retaining tabs  93   a . Annular wall  91  and legs  93  are separated by arcuate openings such as U-shaped openings, as shown. 
     Referring to FIGS. 7 and 10, filter cap  80  has an inner annular wall  83  with internal threads  35 . Annular wall  83  houses an opposing series of angled teeth, lower teeth  81  and upper teeth  82 . Prior to installation of a water bottle, projection  93   b  of plunger  90  is in an upper position in between upper teeth  82 . Upon installation of water bottle  20 , projection  93   b  will move straight down about ¼ inch (equal to the distance that the lower edge of the water bottle must travel to meet the filter cap threads  35 ) until projection  93   b  lies between two lower teeth  81 . As the water bottle is threaded onto the filter cap, projection  93   b  will continue to move downward between the two lower teeth  81 . Referring to FIG. 29, projection  93   b  preferably traverses the path shown by circuit  188 . 
     Filter cap  80  and plunger  90  are preferably designed such that projection  93   b  does not touch either the upper surface  82   a  of upper teeth  82  or the lower surface  81   b  of lower teeth  81  (see FIG.  10 ), so that projection  93   b  is not stressed during use. While other dimensions may obviously be used, in a preferred embodiment upper teeth may have a length equal to the length of projection  93   b  teeth  81 . For example, in the preferred embodiment, the shorter and longer sides of upper teeth  82  may have a length of 0.062 and 0.109 inches, respectively, while the shorter and longer sides of lower teeth  81  may have a length of 0.253 and 0.294 inches, respectively. (The individual teeth may vary slightly in length, given the individual sections of the collapsible cored use to mold the filter cap.) By designing the filter cap so that the lower teeth  81  are longer than the upper teeth  82 , this ensures that follower projection  93   b  will index over and into position so that when threading the filter cap onto the bottle, projection  93   b  will continue down the correct channel between the lower teeth, and avoid backtracking of projection  93   b  due to clockwise rotation of the threading action. 
     In operation, and referring now to FIGS. 7-16, plunger  90  rotates as filter shutoff device  30  is replaced and connected to new water bottles. Plunger rotation is caused by the interaction of projection  93   b  with opposing angled teeth  81 ,  82 . During normal water dispensing and filter use, plunger  90  is positioned at a vertical level that permits threaded connection of threads  35  of filter cap  80  with threads  25  on the neck of bottle  20  (FIG.  2 ). Plunger  90  is maintained by spring  57  in the highest vertical position permitted. As plunger  90  incrementally rotates during the successive use of water bottles, projection  93   b  moves within opposing teeth  81 ,  82 , which are off-set and angled to induce this rotation. (This continues until retaining tab  93   a  reaches locking window  84 . Upon locking, which is further discussed below, plunger  90  is locked at a vertical level such that the plunger covers threads  35  and interferes with engagement of the threads by a water bottle. 
     Referring to FIGS. 13-16, “lead-in” angled surfaces  93   a   1 , and  84   a  of retaining tab  93   a  and locking window  84 , respectively, are provided. These surfaces are angled to allow the locking tab to cam its way onto the inside surfaces of window “frame”  84   a  as a result of the rotation of plunger  90  during the last few iterative movements of projection  93   b  between teeth  81   82 , just prior to the locking of tab  93  within window  84 . This camming action flexes leg  93  toward the filter throat until retaining tab  93   a  clears ramped surface  84   a  and enters the window itself. 
     The locking mechanism is also designed to reduce the risk of losing the locking function, as now described. Referring to FIG. 16, if the user tries to connect the bottle threads to filter shutoff device  30  after the locking mechanism has been engaged (and, thus, retaining tab  93   a  lies within locking window  84 ), a downward force is exerted on plunger  90  by the water bottle end. This pushes retaining tab  93   a  against the bottom surface  84   b  of locking window  84 . Bottom surface  84   b  and the adjacent bottom surface of locking tab  93   a  are each angled slightly in a downward direction moving away from filter throat  91   a . This results in locking tab  93   a  having a tendency to “bury” itself deeper into locking window  84 , rather than trying to slide back toward the filter throat and losing engagement with the locking window. 
     Referring to FIGS. 9 and 11, opening  85  is provided as a relief, to ensure that projections  93   b  on the plunger do not shear off as the plunger is installed in addition, opening  85  provides a visual indication to the installer, giving the installer the ability to choose the number of iterations necessary before lock-up of the filter occurs. For example, in the device shown in FIG. 11, fifty teeth  81 ,  82  and three openings  85  are provided about the inner circumference of cap  80 . The positions of openings  85  allow a design in which, by initially locating the plunger so that projection  93   b  is situated in an opening  85 , filter shutoff device  30  can be configured to provide any number of iterations necessary to correlate the volume of bottles being used and the filter rating, and trigger filter lock-up. 
     The openings of plunger  90  should be appropriately sized, as now described. First, plunger top  92  is preferably provided with a restricted circular throat  92   a , to reduce water hammer through the plunger. In the preferred embodiment, this opening has a diameter of about ¾ inches, which is 0.442 in 2 . Once the opening in plunger top  92  is sized, the vertical slots in apron  91  of plunger  90  are then sized, by providing slots having an area such that the effective surface area of the openings permitting water travel out the side annular walls of plunger  90  is equal to the surface area of throat opening  92   a  in plunger top surface  92 . 
     Given this preferred plunger size and configuration, it was found that water will fill the upper chamber of the filter, i.e., above media retaining ring  33  and below cap  80 , relatively slowly, such that water will not be permitted to pass through vent holes  120 . 
     In a particularly preferred embodiment, an early warning signal may be used to notify the user of the impending end of the filter&#39;s useful life. For example, a red flag may be sprung into position within the center of the filter when 90% of the filter&#39;s useful life has expired. As another example, bi-colored icons or a graduated bi-color band  191  (FIG. 12) may be used to indicate that the useful life of the filter is nearing an end, by matching dot or projection  190  on rotating plunger top surface  92 , for example, with band  191 . 
     Filter cap  80  carrying opposed teeth  81 ,  82  may be manufactured by machining a collapsible core, such as those available from Detroit Mold Engineering of Detroit, owned by Cincinnati Millicron (Catalog No. CC-402-PC). When designing the teeth, a proper draft angle is required to insure release from the molding surface. Each of the teeth has a different shape depending on where they are located on the collapsing core. The collapsing action of the DME core is inward, or perpendicular to the primary draw angle of the mold, and works with a specific number of pie shaped segments, as. disclosed in U.S. Pat. Nos. 3,247,548 and 3,660,001, incorporated herein by reference. These pie shapes, usually consisting of twelve segments, may have two different sizes, e.g., six large and six small. Each segment should be machined separately. 
     Another aspect of the invention concerning vent holes  120  is now discussed. Referring to FIG. 3, when water bottle  20  is inverted into a dispensing position, a seal is created between shutoff filter rim  37  and bottle seat ledge  27   a . To allow continuous dispensing without lock-up, air passes from outside the filter through vent holes  120  in filter cap  80  (FIG.  6 ), and into water bottle  20 . When the filter is initially installed on the bottle and the bottle is rotated into the functioning position, during the time that water flows down and wets and fills the filter media, the water flow path that presents the least amount of resistance, and thus the path the water actually travels, is through the vent holes. This is believed due to a water hammer effect such that the existing air already in the filter will tend to escape through these vent holes, carrying water with it. This initial condition may result in some (less than about 1 cc.) untreated water escaping through the vent holes and into the treated water. This initial condition may result in a failure to comply with NSF regulations regarding lead treatment, for example. 
     To solve this problem, a reduced throat diameter “D” (FIG. 6) is provided, e.g., the throat diameter was reduced from about 2 inches to about ¾ inches, for example. In the preferred embodiment, six vent holes  120  are provided on the upper surface of filter cap  80 , and pass completely through the filter cap. One preferred size of the vent holes is about 0.031 inches; however the vent holes may be sized larger, in which case fewer than six may be used. Vent holes  120  permit air to escape from the filter, and flow between the bottle threads and into the water bottle. Using this restricted throat diameter, when water bottle  20  is inverted, water slowly passes into filter shutoff device  30 , such that the water level in the device slowly rises. In a particularly preferred embodiment, 0.7266. minutes was required for 3500 ml. of water to, flow through a filter shutoff device having a throat diameter of about ¾ inches (a fill rate of 4,817 ml./min), whereas only 0.1728 minutes was required for the same volume of water to flow through an identical filter with a throat diameter of about 1.5 inches (a fill rate of 20,255 ml./min). It was noted that water hammer continued to cause water passage through the vent holes until the fill rate was reduced below about 7,500 ml./min. Unlike prior art designs, even during the filling stage and before the water reaches its final level within the filter due to the pressure head created by the bottle neck, the water level never reaches above the level of vent holes  120 . With this design, then, water never flows out through the vent holes, allowing NSF compliance, and reducing spillage and mess. 
     Referring now to FIGS. 17-25, an alternative embodiment of the filter shutoff device of the present invention, generally referred to as  130 , is shown. Referring first to FIG. 17, filter cap  180  has opposed vertical walls  139  ending in tabs  139   a  designed to removably snap into the Opening formed by rim  141   a  of ring  141 . The outside walls  141   b  of ring  141  preferably taper, as shown, to make room for this removable snap fit. A filter, not shown, is contained within opening  152  created by this connection 
     Referring still to FIGS. 17-25, filter cap  180  is assembled to a monitoring and locking device, generally referred to as  140 , which consists of rotary indexing ring  141  and stationary ring  143 . Ring  141  includes a number of teeth  144   a  axially spaced about the upper internal periphery of the ring, and a flexible or spring-loaded tab  145  positioned along the outside edge of ring  141 , having a distal end  145   a  and a function described further below. Ring  143  includes a curved annular disc  144  with two-curved springs  146 , which may be helically-shaped, opposing tabs  148  on the ring periphery, and two opposed indexing tabs  147 . Indexing tabs  147  each have triangular projections  147   a ,  147   b , preferably shaped as shown. 
     Referring now to FIGS. 23-25, during normal water dispensing and operation of the filter, teeth  144   a  are positioned as shown in FIG.  23 . Each time filter shutoff device  130  is removed from an empty water bottle  20  and threaded to a new water bottle, device  140  is shaped, sized and configured to provide an rotary indexing movement such that tab  147  is advanced in a counter-clockwise direction (as seen when looking downward on device  130 ) the distance of one tooth, as now explained. Each time device  130  is removed from an empty water bottle, ring  143  is forced upward by springs  146 , causing two adjacent teeth  144   a  to be positioned adjacent triangular projection  147   b , as shown in FIG.  24 . The interaction of the leading tooth  144   a   1 , against projection  147   b  causes an incremental counter-clockwise rotation of ring  144  and indexing tab  147  (when viewing device  130  from a downward direction). Then, when a new water bottle is threadably attached to device,  130 , ring  143  is forced in a downward direction by the neck of the bottle. When this occurs, indexing tab  147   b  moves downward as well so that leading tooth  144   a   1 , now contacts projection  147   a , causing another incremental counter-clockwise rotation of ring  144  and indexing tab  147 , as shown in FIG. 25, such that trailing tooth  144   a   2 is in the position that leading tooth  144   a   1 , of FIG. 23 previously occupied. 
     In this manner, ring  143  is continued to be advanced in a rotary direction until the disassembly of device  130  from an empty water bottle causes spring-loaded tab  145  to reach opening  150  in vertical wall  139  of filter cap  180 . Now, distal edge  145   a , which was earlier prevented from doing so (see FIG.  18 ), enters opening  150  and halts further rotary movement of ring  143  and indexing tab  147 , as shown in FIGS. 19-20. When this occurs, device  130  can no longer be threadably connected to a new water bottle since the presence of distal end  145   a  within opening  150  prevents downward movement of ring  143 , so that ring  143  remains in a position that covers internal threads  135  of filter cap  180 , as shown in FIG.  20 . 
     As will now be understood, the components of filter monitoring and locking device  140  may be shaped and oriented such that the number of teeth used corresponds to the number of bottles which may be used before the filter is disabled. For example, if 45 teeth are used for 3-gallon bottles, then the filter disable device will activate after 135 gallons of water have been used. 
     In an alternative preferred embodiment, shown in FIGS. 26-28, filter monitoring and locking device  240  is of one-piece construction, and includes a single molded component consisting of upper ring  243  and lower ring  241 . Indexing tab  247  extends down from ring  244  and includes an upper opening  247   c  with a pointed tab  245 . Indexing tab  247  also includes a lower, stepped series of openings  247   d.  In a similar manner as described above, ring  243  and tab  247  are rotary indexed in a counter-clockwise direction (again, when viewing device  240  from above) by the stepped orientation and interaction of openings  247   d  with teeth  244   a , as shown in FIGS. 26 and 28. As the filter shutoff device is used, removed and then connected to a new water container, tab  247  rotates and pointed tab  245  moves within succeeding angled openings  260 . When tab  247  reaches a position permitting the entry of tab  245  into opening  270  on ring  241  (FIG.  27 ), further rotary movement of ring  243  ceases, disabling the filter shutoff-device by preventing its threaded connection with water container  20 . 
     It will be understood that the filter shutoff device of the present invention may be used with water containers other than the inverted water bottles shown in the drawings. For example, the device may be used with water pitchers or sports bottles. It will also be understood that the filter shutoff device may be used with a variety of water dispensing devices, and a variety of filters, other than those specifically described here. 
     While the invention has been described with reference to a threaded connection between filter shutoff device  30  and water bottle  20 , it will be understood that device  30  may be modified for use with water containers that are not intended to be threadably connected to device  30 . For example, filter shutoff device  30  could be used with non-threaded connections between device  30  and water bottle  20  such as those described in U.S. Pat. Nos. 5,222,531 and 5,289,855, incorporated herein by reference, such that a cap could be press-fit onto the filter device. As another example, instead of both the water container and the filter shutoff device having threads, one could have a partial thread and the other a simple projection that would engage the partial thread when the filter shutoff device is rotated; this could act as a helical ramp for the projection, pulling the two components tightly together. 
     The above description is not intended to limit the meaning of the words used in the following claims that define the invention. Rather, it is contemplated that future modifications in structure, function or result will exist that are not substantial changes and that all such insubstantial changes are intended to be covered by the claims.