Drinking water filter

A water filtration system, and a filter and timer therefor. The system includes a primary container defining a holding chamber and a secondary chamber defining a filtering chamber at least partially within the holding chamber but spaced above the bottom wall of the holding chamber. The filter assembly is removably connected to the secondary container and comprises a cannister containing a filter disposed generally below the lower end of the filtering chamber, the cannister having inlet means communicating with the filtering chamber and outlet means disposed below the inlet means and communicating with the holding chamber. The timer is connected to the filter and includes a tube with an indicator movable longitudinally therein through a non-gaseous fluid having a specific gravity different than that of the indicator.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention pertains to the filtration of water, primarily for 
drinking purposes. 
2. Description of the Background 
The importance and desirability of filtering water prior to drinking is 
becoming increasingly apparent. Water which is classified as potable 
nevertheless often contains chemicals or other substances which, while not 
necessarily likely to cause immediate life-threatening illness, may 
nevertheless be less than ideal in terms of the long-term health of the 
consumer and may also make the water aesthetically unpleasing. 
One of the best filtering media is activated carbon, and carbon filters, 
for filtering air, water and other substances, are well known. One is 
shown in U.S. Pat. No. 4,306,971. However, a carbon filtering medium has a 
limited life in two respects: first, the life of the carbon, in terms of 
its ability to continue to adsorb contaminants and the like, is limited. 
Secondly, and especially where the carbon is being used to filter water, 
bacterial growth can occur in the carbon after a certain period of time, 
which also, therefore, limits the life of the carbon for purposes of 
filtering water which is to be consumed. 
In the past, it has been known to protect carbon in filters against 
bacterial growth by the use of silver in association with the carbon. 
However, it is now known that the silver is dangerous, and should not be 
used in a filter for handling drinking water. 
For both of these reasons, it is desirable that there be a simple and 
inexpensive way to time the life of a filter to alert the consumer when it 
is time for the filter to be changed. It is especially desirable that the 
timer be connected with the filter itself, and that the filter and timer 
be adapted for use in a filtering container so that the indication that 
the filter should be changed can be readily observed by a consumer without 
trouble and without disturbing the timer, filter and/or container. 
It has been known, for other purposes, to provide timers which operate on 
the general principle of an indicator member moving lengthwise along a 
tube filled with a fluid having a specific gravity different from that of 
the indicator. Such devices are shown in U.S. Pat. No. 3,025,665; U.S. 
Pat. No. 3,553,959; U.S. Pat. No. 4,090,356; and U.S. Pat. No. 4,228,649. 
In some of these devices, the indicator has a lower specific gravity than 
that of the fluid, so that it rises in the tube, whereas in others, the 
indicator has a higher specific gravity so that it falls in the tube. 
The timers disclosed in these prior patents are intended for other uses, 
typically uses over much shorter ranges of time than the life of a water 
filter, and under circumstances in which there is no particular problem in 
providing for ready visibility of the position of the indicator along the 
tube. 
Also, these devices are intended to be reset and reused, which is typically 
done by inverting the tube so as to allow the indicator to begin travel 
from the opposite end of the tube from that employed in its last 
longitudinal movement. 
However, a timer associated with a water filter should not be resettable, 
so that the consumer cannot inadvertently use the filter beyond its 
intended life. On the other hand, the travel of the indicator in a water 
filter should not begin prematurely, i.e. before the filter is put into 
use, so that the consumer will not replace and discard the filter too 
soon. Furthermore, inversion is not a desirable way even to initially set 
the position of an indicator in the context of a water filtration system. 
Therefore, there is need for a means for positively fixing such an 
indicator at the beginning of its intended stroke of travel, but with such 
a means being readily releasable when the filter is put into use. 
SUMMARY OF THE INVENTION 
The present invention provides a water filtration system suitable for home 
or other consumer use, as well as a filter and a timer for the filter, all 
of which are particularly well adapted for consumer filtration of water 
intended for drinking purposes. 
The overall system includes a primary container having a bottom wall and 
side walls defining a holding chamber. A secondary container defines a 
filtering chamber having upper and lower ends. The secondary container is 
mounted on the primary container at least partially within the holding 
chamber but with the filtering chamber spaced above the bottom wall of the 
primary container. 
A filter assembly is connected to the secondary container. The filter 
assembly comprises a cannister containing filter means disposed generally 
below the lower end of the filtering chamber. The cannister has inlet 
means communicating with the filtering chamber and outlet means, disposed 
below the inlet means, and communicating with the holding chamber. Thus, 
water placed in the filtering chamber will pass, by gravity, through the 
filter and into the holding chamber until it is removed for drinking 
purposes. 
The timer, which is also gravity operated, is connected with the cannister 
and operative to produce a visual indication, visible from above the 
primary container, when the filter nears the end of its life. 
More specifically, the timer includes a tube connected with the cannister 
and having upper and lower ends. An indicator member, in the tube, is 
sized for lengthwise movement in the tube. A non-gaseous fluid 
substantially fills the portion of the tube not occupied by the indicator 
member. This fluid has a specific gravity different than that of the 
indicator member, preferably greater than that of the indicator member so 
that the latter will rise in the tube and be visible from above the 
primary container. The relative physical properties of the indicator 
member, the fluid and the tube, e.g. the viscosity of the fluid, the shape 
of the indicator member, and the clearance between the indicator member 
and the inner walls of the tube, are adapted to time the travel of the 
indicator member along the length of the tube to correspond to the life of 
the filter means. If the indicator member has a lengthwise flowway, its 
internal size can be used to control the travel, reducing difficulties of 
close external tolerances. 
The tube preferably extends upwardly to or beyond the top of the cannister 
so that the upper end of the tube, which serves as its viewing portion, 
can be readily seen by looking down into the filtering chamber. 
Preferably, the timer has a transparent window across the upper end of the 
tube and disposed for visibility from above the filter. This allows the 
consumer to easily see if the indicator has reached the end of its travel 
even though the entire filter and timer may remain within the primary 
and/or secondary containers, or even under water. To enhance this easy 
visibility, the indicator member may have a pigmented surface visible 
through the window when the indicator is disposed adjacent thereto, and 
the fluid may have a contrasting pigment. 
A releasable retainer means is provided for temporarily holding the 
indicator member adjacent one end, preferably the lower end, of the tube. 
In a preferred embodiment, a self-healing seal is disposed in a wall of 
the tube and closes the tube adjacent its lower end, and the retainer 
means comprises a retainer pin extending through the seal and into the 
indicator member. When a new filter is put into use, the consumer first 
removes the pin, thereby releasing the indicator member for its lengthwise 
travel along the tube. The self-healing seal immediately closes the space 
previously occupied by the pin as the pin is removed so that the fluid 
does not leak from the tube. A grip may be provided for facilitating 
removal of the pin, or the pin may be arranged for automatic removal when 
a new filter is taken from its package. 
Accordingly, a principal object of the invention is to provide an improved 
water filtration system particularly well adapted for consumer filtering 
of drinking water. 
Another object of the invention is to provide a filter for drinking water 
which has a timer, indicative of the life of the filtering medium, 
incorporated therewith. 
A further object of the present invention is to provide such a timer with 
means for positively preventing movement of the indicator until the filter 
is put into use. 
Still another object of the present invention is to provide such a timer in 
which a visual indication of the end of the life of the filtering medium 
is conspicuous when viewing the timer from above a water container in 
which it is disposed for use. 
Yet another object of the invention is to provide such a timer with an 
indicator member having a lengthwise flowway. 
Still other objects, features and advantages of the invention will be made 
apparent by the following detailed description, the drawings and the 
claims.

DETAILED DESCRIPTION 
Referring first to FIG. 1, an overall water filtration system, intended 
primarily for consumer use in filtering water for drinking purposes, 
comprises a primary container 10 which is generally in the form of a 
pitcher adapted to receive and cooperate with the remainder of the system. 
The container 10 includes a bottom wall 12 and side walls 14 defining a 
holding chamber 16 for holding the water which has already been filtered. 
Container 10 also has a handle 18 and a spout 20. 
The system further includes a secondary container 22. This container 
defines in its interior a filtering chamber 24 in which water can be 
placed for filtering. At its upper end, the container 22 has an outwardly 
projecting flange 26 which is sized and shaped to rest on the upper edge 
of the pitcher 10 and suspend the container 22 therein. This positions the 
container 22 at least partially within the holding chamber 16, and more 
specifically in the preferred embodiment shown, virtually entirely within 
the primary container 10. The size of the container 22 is such that, when 
so suspended from the upper edge of the pitcher 10, the filtering chamber 
24 is spaced substantially above the bottom wall 12 of the pitcher 10. 
Terms such as "above," "below," "upper," and "lower" are used herein for 
convenience to denote the parts of the apparatus when the apparatus is 
positioned for normal use, as shown in the drawings, and should not be 
construed so as to otherwise limit the scope of the claims. 
The side walls 30 of the secondary container 22, which are otherwise 
generally cylindrical, include a generally longitudinally extending, 
radially inwardly projecting portion 32, aligned with spout 20 in use, 
which forms, on the exterior of container 22, a groove to permit water to 
pass more readily from the holding chamber 16 past the secondary container 
22 and through the spout 20 so that container 22 does not have to be 
removed to draw water for use. 
The bottom wall 28 of the secondary container 22 has an opening defined by 
an annular downwardly projecting rim 34 from which an annular flange 36 
extends laterally inwardly. The filter assembly 38, to be described more 
fully below, is mounted on the secondary container 22 by means of a flange 
40 thereof sized to rest on flange 36. Flange 40 is also sized so as to 
form a friction-type seal against rim 34. 
A cover 42 is provided for closing the upper end of container 22, and 
thereby also closing container 10, for the usual purposes. 
Referring now to FIG. 2 in conjunction with FIG. 1, the filter assembly 38 
and its use will be described in greater detail. Filter 38 includes a 
cannister comprising a barrel portion 44 and a cover 46. The cover 46 
includes the aforementioned flange portion 40 as well as a central 
upstanding generally tubular projection 48. The cover 46, in the portion 
located below and laterally outwardly of the projection 48, has a number 
of inlet openings 50 therethrough. By comparison with FIG. 1, it can be 
seen that, in use, these inlets 50 lie at the bottom of filtering chamber 
24 and in communication therewith. Thus, water can pass by gravity flow 
from the filtering chamber 24 through the inlets 50 and into the barrel 44 
of the filter cannister. 
The cannister 44 is packed with a filtering means or medium 52, preferably 
a mixture of activated carbon and a weak cation exchange resin. The bottom 
wall 53 of cannister barrel 44 has a number of outlet openings 54 therein. 
Thus, water entering the cannister 44 through inlets 50 passes through the 
filtering medium 52, whereby impurities are adsorbed, and thence out 
through the outlets 54 and into the holding chamber 16. Suitable means, 
well known in the art, can be used to prevent small particles of the 
filtering medium 52 from entering the water in the holding chamber 16. For 
example, the inlet and outlet openings can be covered with a very fine 
mesh mechanical filter. 
As impurities are thus adsorbed, the carbon portion of the filtering medium 
becomes saturated and loses its effectiveness for further filtering 
purposes. Also, unprotected by silver, which is now considered dangerous 
for use in connection with drinking water, bacteria can begin to grow in 
the filtering medium, presenting a new problem to replace that which the 
filtering is intended to solve. 
Accordingly, there is provided a timer which is completely gravity 
operated, simple to use and to read, and which provides the user with a 
signal, which is in fact difficult to ignore, when it is time to change 
the filter. Use of the timer and changing thereof are further ensured by 
the fact that the timer is incorporated in the filter itself. 
The timer includes a cylindrical tube 56 which extends centrally and 
vertically through the cannister 44, 46. The lower end of tube 56 is 
mounted in an upstanding annular rim 58 formed integrally with the bottom 
wall of the cannister 44. Tube 56 extends upwardly through the barrel 44 
of the cannister and through the extension 48 of the cover 46. A 
transparent closure member 60, which may be formed for example of glass or 
a suitable thermoplastic, serves to close both the upper end of tube 56 
and the upper end of extension 48 and to properly position or fix the 
upper end of tube 56. The closure 60 also forms a window in the form of a 
lens 62 extending across the top of tube 56, which in turn projects 
outwardly from the upper end of extension 48. 
More particularly, the closure 60 includes an annular downwardly depending 
skirt 64 sized for a fairly snug fit about the outer diameter of tube 56 
and a similar fit against the inner diameter of an inwardly projecting lip 
48a extending integrally inwardly from extension 48. Closure 60 may also 
have an outwardly extending lip 66 which extends out to contact the inner 
diameter of extension 48 just below lip 48a for further stability. 
The closure 60 also includes a central downward projection 68 having on its 
underside a flat seating surface for the indicator member to be described 
below. The outer surface of window 62 is convex so as to make the view of 
the indicator through the window even more conspicuous. It will be 
appreciated that the window 62 can be readily viewed in chamber 24 by a 
user simply removing the cover 42 and looking down upon the device. 
The timer includes an indicator member in the form of a solid, generally 
cylindrical float 70 initially releasably fixed in the lower end of tube 
56 in a manner to be described more fully below. The remainder of the tube 
56 is substantially filled with a non-gaseous fluid 72. By "substantially 
filled" is meant that there is enough fluid to allow the float 70 to float 
thereon to a position substantially adjacent the projection 68 of the 
closure 60. However, if there is a small amount of air or other fluid also 
within the tube 56, as is sometimes desirable in order to allow for 
thermal expansion of the fluid without leakage, the tube 56 would still be 
considered "substantially filled" with the fluid, as that term is used 
herein. 
The fluid 72 must have a specific gravity different from that of the float 
70. Because of the nature of the use of this timer and, in particular, the 
fact that it is highly desirable that the user be able to read the 
indicator when looking down on the device, it is highly preferred that the 
specific gravity of the float 70 be less than that of the fluid 72 so that 
the travel of the float 70 in use will be upward. However, it is 
conceivable that arrangements might be devised in which filter timers for 
this purpose could have indicators which move downardly in use. 
The size of the clearance between float 70 and tube 56, coupled with the 
length of the cylindrical side walls of float 70 is chosen so that float 
70 will remain in the orientation shown during its travel, specifically 
with a stub 74 projecting endwise from the main body of float 70 
uppermost. Stub 74 has an end surface 76 which is sized and configured to 
mate with the seating surface defined by the bottom of projection 68, and 
this surface 76 is preferably pigmented for easier viewing through window 
62. In addition, the fluid 72 may be pigmented in a contrasting color. 
Thus, for example, the fluid 72 might be green, whereas the surface 76 
might be red. Then, any time the user opens the cover 42 and sees that the 
window 62 shows red rather than green, it will be readily apparent that it 
is time to replace the filter 38. 
The relative properties of the float 70, the fluid 72 and the tube 56 are 
chosen so that the time it takes for the float 70 to move from the lower 
end of tube 56 to the upper end will correspond to the useful and helpful 
life of the filtering medium 52. "Correspond," as used herein, does not 
necessarily mean that the time of travel of the float 70 is exactly equal 
to the life of the medium. Indeed, it is preferable that the time of 
travel of the float 70 be somewhat less than the projected life of the 
medium, as a safety measure. For a typical household drinking water 
filter, the time of travel of the float might be on the order of thirty 
(30) to forty-five (45) days. 
Several relative physical and chemical properties can be used to adjust 
this timing. Clearly, the specific gravity of the float 70 and fluid 72 
must be different, or the float will not move at all However, by varying 
the degree of difference in specific gravity, the timing can be affected. 
However, in many preferred embodiments, particularly because of the 
relatively long time desired for the stroke of the float 70, it is 
desirable to also utilize other relative properties. For example, the 
viscosity of the fluid 72, which can be but is not necessarily a function 
of specific gravity, can be used to control the speed of travel of the 
float 70. In conjunction with this, it can be seen that the physical 
properties of the tube 56 relative to the float 70 can also come into 
play. For example, even if the fluid 72 is very viscous, if there is a 
large clearance between the float 70 and tube 56, the float could move 
more rapidly than if there is a small clearance. Thus, the relative sizes 
of the float and tube, whether or not the inner surface of the tube and 
the outer surface of the float are of mating configurations, and the 
length of the portion of the float having the largest diameter, can all be 
used to further refine the timing. 
At least some of these properties, notably viscosity, vary with 
temperature. In the system described in aforementioned U.S. Pat. No. 
4,228,649, pains were taken to make the travel time of the indicator 
independent of temperature. However, in the present invention, the 
temperature/viscosity relation, which exists for many suitable fluids, can 
be used to advantage to provide a self-adjusting travel time. Thus, for 
example, by use of a suitable fluid whose viscosity varies inversely with 
temperature, it can be ensured that the travel time will be shorter in 
warmer environments where microbial growth would begin sooner. In an 
exemplary embodiment, the fluid may comprise polydimethylsaloxane. 
It is important for the sake of accurate timing that the float 70 be 
released for movement as soon as the filter is put into service, but not 
prematurely. Also, because this device is for consumer use, the means of 
releasing the float should be simple to operate and fairly conspicuous. 
To these ends, the lower end of tube 56 is provided with a closure in the 
form of a self-healing seal 78. This seal may be comprised of a suitable 
elastomer, such as the type which is used to seal the tops of medicine 
vials from which liquids are extracted by hypodermic syringes. 
Referring now also to FIG. 4, a retainer pin 82 extends upwardly through 
the seal 78 and into an elastomeric lower part 70a of float 70. This 
releasably retains float 70 adjacent the lower end of tube 56. A grip 84 
is connected to the outer end of pin 82 and extends downwardly through a 
hole 80 in the bottom of cannister barrel 44 and projects downwardly from 
the filter by a substantial distance. Conspicuous indicia, such as red or 
other brightly colored arrows 86, are imprinted on the grip 84 to remind 
the user to pull downwardly on the grip when placing the filter into 
service. 
FIG. 5 shows what happens when this is done. The pin is removed from the 
part 70a and from the seal 82, which immediately seal in upon the prior 
locus of the pin to prevent leakage. The float 70 then begins to move 
upwardly until its stub 74 finally seats against the underside of window 
62 as shown in FIG. 3. Then, the user will soon notice the change in color 
seen through window 62, and will be reminded to replace the filter. 
FIGS. 6-8 illustrate another embodiment of filter assembly according to the 
present invention. Many of the parts of this second filter assembly are 
similar to those of the first embodiment described above, and to that 
extent, the same reference numerals have been used to designate similar 
parts. 
In the embodiment of FIG. 6, the barrel 44 of the cannister differs from 
that of the preceding embodiment in that, instead of the small rim 58, 
there is, molded integrally with barrel 44, an upstanding tubular sheath 
90 which extends upwardly the full length of barrel 44, and preferably 
beyond that into cover projection 48. 
Since, in order to mold the sheath 90, and more specifically to remove the 
barrel from the mold, the sheath 90 must have at least a small drift 
angle, it cannot be used as the timer tube per se, because a non-uniform 
inner diameter of the timer tube would make proper timing difficult to the 
extent that it is affected by the clearance with the indicator member. 
However, the sheath 90 can facilitate assembly of the filter in that, when 
the filtering medium 52 is emplaced in the barrel, the sheath 90 will 
prevent the filtering medium from entering the place where the tube 56 for 
the timer needs to be inserted. Then, the tube 56, along with the cover 
46, can be emplaced, the tube 56 passing down along sheath 90 until its 
lower end rests on the bottom wall 53 of the barrel inside sheath 90. This 
abutment retains tube 56 from further downward movement, while cover 46 
and the associated closure 60 prevent upward displacement of tube 56. 
Another difference in the embodiment of FIGS. 6-8 is in the form of the 
indicator member 92. Various factors which affect the timing of the stroke 
of the indicator member have been discussed above, and it has been 
mentioned that, in connection with the solid cylindrical float 70 of the 
first embodiment, its clearance with the timer tube 56 is one such factor. 
However, properly timing the float's travel by a suitable clearance and 
length of the float can present difficulties In addition, the clearance 
between the outside of the indicator member and the inside of the timer 
tube is preferably carefully controlled so as to allow sufficient freedom 
of movement but with a good centering action. 
In the embodiment of FIGS. 6-8, the indicator member or float 92 is not 
solid, as in the first embodiment, but rather has lengthwise flowway means 
for passage of the fluid 72. More specifically, referring to FIGS. 7 and 
8, the float 92 is of two part construction. The major portion is a 
cylindrical sleeve 94. The other portion is a gauge portion 96 located at 
the upper end of sleeve 94. 
Even more specifically, the gauge portion 96 is cruciform in transverse 
configuration, having four radiating arms 98. As shown in FIG. 7, each arm 
98 is undercut at its outer end as indicated at 100. The thicker, 
innermost parts of the arms 98 are sized to be press fit into the upper 
end of sleeve 94, with the upper end of the sleeve fitting into the 
undercuts 100. The thin outer portions of the arms 98 are sized to project 
radially outwardly beyond the outer diameter of sleeve 94, as indicated at 
102, and their amount of such extension, i.e. the maximum transverse 
dimension of gauge portion 96, as measured along two diametrically opposed 
arms, can be carefully controlled so as to provide the proper centering 
action of the entire float 92. This eliminates the need to size the entire 
sleeve 94 for such centering. Thus, the sleeve 94, which represents the 
bulk of the float 92, can be inexpensively made. 
Also, because the rate of travel of the float 92 is dependent, among other 
factors, on the total transverse cross-sectional area of the float, and 
because that area is not solid, but rather has lengthwise flowway means, 
cross-sectional area can be used to help time the stroke of the float 92 
by providing for the flow phenomena to be at least partially of the 
couette type, rather than mainly of the poiseuille type. This, in turn, 
lessens the criticality of the tolerances between the outer surface of the 
float and the inner diameter of the timer tube 56. More specifically, the 
flowway means comprises the interior of the sleeve 94, and the spaces 
between the arms 98 which, as shown in FIG. 8, communicate with the 
interior of sleeve 94. 
Referring again to FIG. 6, since float 92 is hollow at the bottom, a 
retainer pin 104 extends all the way up through the sleeve 94 and into a 
socket 106 (see FIG. 8), in the gauge portion 96 of the float 92. 
The embodiment of FIG. 6 is also provided with a means to ensure automatic 
removal of pin 104, and thus activation of the timer, when the filter is 
put into use. More specifically, when new, the filter assembly shown in 
FIG. 6 is enclosed in a package, in this case in the form of a flexible 
wrapping. This packaging may be aseptic. The outer end of pin 104 has a 
disk-like head 110, which is exposed through the hole 80 in the cannister 
barrel 44 and affixed, as by adhesive, to the wrapping 108. Thus, when the 
wrapping 108 is removed to place a new filter into use, the pin 104 will 
be removed with it. Although, in the embodiment shown, assembly is 
facilitated by positioning the pin head 110 inside the package 108 and 
affixing it thereto by an adhesive, it might be possible, in other 
embodiments, to have the pin 104 extend through the wrapping or packaging, 
with the head 110 on the exterior of the wrapping, to achieve a similar 
automatic removal result. 
A number of the advantages of the invention have been brought out in the 
course of the above discussion. To these it might be added that the system 
is completely gravity operated, requiring no external power source. It is 
simple and practical for consumer use and it resolves many of the problems 
explained above which have been found in prior water filtration devices as 
well as deficiencies in prior timer devices which were not tailored for 
this particular use. Still other advantages will be apparent from the 
overall disclosure. 
It will also be apparent that various modifications might be made to the 
embodiments described above within the spirit of the invention. It is 
therefore intended that the scope of the invention be limited only by the 
claims which follow.