CA2289886A1 - Filtration system with disposable filter and indicator - Google Patents

Abstract

A filter unit suitable for use in a filtration system is disclosed herein, the filter unit having a receptacle having an inlet, an interior chamber, and an outlet. A
filter element may be positioned within the interior chamber of the receptacle, the filter element and receptacle adapted to permit fluid flowing into the inlet of the receptacle to enter the interior chamber of the receptacle, pass through the filter element, and exit the receptacle through the outlet. The filter unit further includes an indicator having a first reservoir in fluid communication with the interior chamber of the receptacle, at least a portion of the first reservoir being visible to a user, and a first flow restrictor positioned between the first reservoir and the interior chamber of the receptacle.

Description

FILTRATION SYSTEM WITH DISPOSABLE FILTER AND INDICATOR
Field of the Invention The present invention relates generally to a fluid filtration system, and more particularly to a fluid filtration system including a disposable filter and indicator.
Background of the Invention As consumers become more health conscious, there is a heightened interest in increasing the quality of water that is utilized for human consumption. In response to this interest, there is much ongoing effort to develop systems which improve water quality by filtering the water to remove contaminants such as chlorine, iron, biological and organic contaminants, microorganisms, lead, and the like which may affect the color, taste, odor and potability of water.
A variety of filtration systems are currently available that assist in reducing the contaminants in water prior to use or ingestion. Such systems typically include a replaceable filter positioned within some type of housing such as a bottle, canteen, pitcher, counter-top, faucet-mounted device or the like.
Some of the currently available filtering systems provide an indication as to when the useful life of the filter has been reached, and the filter must be replaced. It is important to provide an indication that a filter has reached the end of its useful life because a filter that is utilized after its effectiveness has diminished may reintroduce contaminants which have been captured by and are contained within the filter into water flowing through the filter. Frequently, these °end of life" indicators utilize complex mechanisms which may include multiple moving components to determine when the useful life of the filter has been reached. Such indicators are sometimes costly and may need to be reset each time the filter is replaced. In such systems, a user may neglect to reset the indicator or may reset the indicator inaccurately, rendering the indicator useless and potentially permitting the filter to be utilized well past its intended usefulness.
Thus, there remains a need for an inexpensive, reliable and simple water filtration system that provides a clear and reliable indication that the filter should be replaced.

Summary of the Invention In response to the foregoing problems and difficulties encountered by those of skill in the art, the present invention is directed to a filtration system which, in a particular embodiment, includes a filter unit having a receptacle which may include an inlet, an interior chamber, and an outlet. A filter element may be positioned within the interior chamber of the receptacle. The filter element may be formed of a variety of materials such as, for example, granular activated carbon, block activated carbon, membranes, woven and nonwoven fabrics, paper, microporous films, hollow fibers, ceramics, zeolites, ion exchange resins, and the like. The filter element and receptacle are configured so that fluid flowing into the inlet of the receptacle enters the interior chamber of the receptacle and passes through the filter element prior to flowing out of the filter unit through the outlet of the receptacle.
An indicator, which indicates to a user that the filter element should be replaced with a new filter element, may be attached to the receptacle. In selected embodiments, the indicator includes a first reservoir in fluid communication with the interior chamber of the receptacle. A portion of the fluid flowing into the interior chamber of the receptacle will flow into the first reservoir. A first flow restrictor may be positioned between the first reservoir and the interior chamber of the receptacle, the first flow restrictor restricting the amount of fluid which may enter the first reservoir. The first flow restrictor and the first reservoir may be configured such that a predetermined amount of fluid will be contained within the first reservoir when the filter element has reached the end of its useful life, thus indicating that the filter element should be changed.
At least a portion of the first reservoir is visible to a user positioned exteriorly of the filtration system so that a user may visually determine the level of fluid contained within the first reservoir. To accomplish this, in selected embodiments, at least a portion of the first reservoir may be formed from a transparent or translucent material.
In selected embodiments, the indicator may include a second reservoir in fluid communication with the first reservoir. A second flow restrictor or barrier may be positioned between the second reservoir and the first reservoir. In selected embodiments, the second reservoir may be positioned with respect to the first reservoir such that fluid does not enter the second reservoir until the fluid within the first reservoir has reached a predetermined level or position. The second flow restrictor or barrier may be adapted to facilitate the flow of fluid into the second reservoir only when the fluid within the first reservoir has reached a predetermined level.

In particular embodiments, a water-soluble dye is disposed within the second reservoir. As fluid enters the second reservoir through the second flow restrictor, the water-soluble dye dissolves in the fluid. This colored fluid may then flow through the second flow restrictor or barrier into the first reservoir where it is visible to a user.
In selected embodiments, an electrical indicator may be utilized in conjunction with the first and/or second reservoir. In such a system, the fluid within the first or second reservoir completes a circuit when the fluid has reached a particular level. A
visual indicator such as, for example, a light emitting diode ("LED") or liquid crystal display ("LCD") may be electrically connected to the circuit so that a visual signal or message may be given to the user when the circuit is completed. Additionally, a sound-generating device that emits a tone, buzz, voice or other sound may be activated by the completion of the circuit. The visual indicator and sound-generating device may be utilized independently or in conjunction with each other.
Particular embodiments of the filtration system may further include a housing.
In selected embodiments, the housing may include an inlet, a flow chamber in fluid communication with the inlet, an outlet, and a lid. The filter unit may be positioned within the flow chamber of the housing. A portion of the housing may be translucent or transparent to enable a user to visually determine the level of fluid contained within the first reservoir. The housing lid may be attached to the housing so that the filter unit may be removed therefrom. In alternate embodiments, the filter unit may slidingly engage an opening in the housing.
Other objects, advantages and applications of the present invention will be made clear by the following detailed description of embodiments of the invention and the accompanying drawings wherein reference numerals refer to like or equivalent structures.
Brief Description of the Drawinas Figure 1 is a partial cross-sectional side view of an embodiment of a filtration system according to the present invention.
Figure 2 is a partial cross-sectional side view of an embodiment of a filter unit according to the present invention.
Figure 3 is cross-sectional side view of another embodiment of a filtration system according to the present invention.
Figure 4 is a partial cross-sectional side view of yet another embodiment of a filtration system according to the present invention.

Figure 5 is a partial cross-sectional side view of an embodiment of an indicator according to the present invention.
Figure 6 is a partial cross-sectional side view of another embodiment of an indicator according to the present invention.
Figure 7 is a partial cross-sectional side view of yet another embodiment of an indicator according to the present invention.
Detailed Description In response to the foregoing challenges which have been experienced by those of skill in the art, the present invention, as depicted in Figure 1, is directed to a filtration system 10 which, in selected embodiments, includes a housing 12. Figure 1 depicts the filtration system 10 in cross-section, the filtration system 10 being symmetrical about the plane through which the cross-section has been taken. The housing 12 may be formed of a variety of materials such as, for example, plastics, metals, ceramics or any combination thereof. The housing 12, which is shown in Figure 1, includes an inlet 14. The inlet 14 may be configured to engage a variety of fluid sources, such as, for example, faucets, pipes, hoses and the like. A flow chamber 16 is in fluid communication with the inlet 14.
Thus, fluid entering the housing 12 through the inlet 14 enters the flow chamber 16.
A filter unit 22 is positioned at least partially within the housing 12. The filter unit 22 may be replaced with a new filter unit 22 when the useful life of the filter element 26, disposed within the filter unit 22, has been reached.
To enable the filter unit 22 to be easily replaced, the housing 12, in selected embodiments and as shown in Figure 1, may include a lid 20. The housing lid 20 may be attached to the housing 12 in a variety of ways, such as, for example, a hinge or flap. In alternate embodiments, the lid 20 may be configured to securely engage the housing 12, such as, for example, by a snap-fit, press-fit, threaded engagement of the lid 20 and the housing 12, flexible lock arms positioned on either the lid or the housing 12 which engage a shoulder or lip positioned on either the housing 12 or the lid 20, and other similar mechanisms. In alternate embodiments, the filter unit 22 may otherwise engage the housing 12, such as, for example, slidingly engaging an opening in the housing 12. In this manner, the filter unit 22 may be removed from the housing and replaced with a new filter unit 22.
The filter unit 22 includes, in selected embodiments, a receptacle 24. A
variety of materials may be utilized to form the receptacle 24 such as, for example, plastics, metals, ceramics or any combination thereof. In selected embodiments, at least a portion of the receptacle 24 is formed from a translucent or transparent plastic such as, for example, acrylic, polycarbonate, polyvinylchloride and the like.
The receptacle 24 may include an inlet 28. As shown in Figure 1, the inlet 28 includes a disk having apertures 30 formed therein so that fluid may flow from the chamber 16 into the interior chamber 32 of the receptacle 24.
The filter element 26 may be positioned within the interior chamber 32 of the receptacle 24. The filter element 26 may be formed of a variety of materials such as, for example granular activated carbon, block activated carbon, membranes, woven and nonwoven fabrics, and the like. As used herein the term "nonwoven fabric"
refers to a web having a structure of individual fibers or threads such as, for example, polymer, glass, pulp or other staple fibers. These fibers are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, wet- and dry-laid processes, and bonded carded web processes.
When the filter element 26 has reached the end of its useful life, the filter unit 22 may be removed and replaced with a new filter unit 22.
The filter element 26 depicted in Figure 1 and Figure 2 is a cylindrical block of activated carbon having a hollow core 36. Figure 2 is a partial cross-sectional view of the filter unit 22. A cover 38 is attached to and covers the upper portion of the filter element 26. The cover 38 may be formed from many different materials including, for example, plastics, metals and ceramics in a variety of forms such as, for example, a solid planar disk or a fluid impervious film. The cover 38 is secured to the filter element 26 in a manner that prevents fluid from entering the hollow core 36 without passing through the filter material. In one embodiment, the cover 38 may be secured to the filter element 26 with an adhesive. Thus, fluid enters the receptacle 24, flows through the filter element 26 to the hollow core 36. The cover 38 and the bottom surface 33 of the interior chamber 32 prevent fluid from passing out of the receptacle 24 without passing through the filter element 26.
In selected embodiments, the filter material may extend across the upper portion of the filter element 26 so that a cross-section taken through the long axis of the filter element 26 would be shaped as an inverted "U". In such an embodiment, the cover 38 would not be required as fluid entering the hollow core 36 from the upper portion of the filter would be required to pass through this additional filter material.
The filter element 26 is secured to the bottom surface 33 of the interior chamber 32 so that the hollow core 36 of the filter element 26 is aligned with the outlet 34 of the receptacle 24. In the embodiment depicted in Figure 1, the hollow core 36 and the outlet 34 are aligned with the outlet 18 of the housing 12. Additionally, the filter element 26 is secured to the bottom surface 33 so that fluid may not flow between the filter element 26 and the bottom surface 33. In one embodiment, the bottom surface 33 may be secured to the filter element 26 with an adhesive. In this manner, fluid entering the interior chamber 32 of the receptacle 24 must pass through a predetermined thickness of filter material prior to exiting the filter unit 22 and housing 12. This helps to prevent unfiltered fluid from passing out of the filter unit 22. In alternate embodiments, seals and/or sealing material may be selectively placed within the filtration system 10 to ensure that no unfiltered fluid exits the system.
The receptacle 24 is configured so that fluid may enter the receptacle 24, pass into the interior chamber 32 and through the filter element 26. The receptacle 24 may be variously formed to permit fluid to enter the interior chamber 32. For example, and as shown in Figure 1, fluid may enter the receptacle through the apertures 30 that are formed in the inlet 28 of the receptacle 24. The fluid may then pass through the filter element 26 to the hollow core 36 of the filter element 26. The fluid may then flow from the hollow core 36 out of the filter unit 22 through the outlet 34 of the receptacle 24.
The filter unit 22 depicted in Figure 2 includes a plurality of apertures 70 formed in the wall 72 which permits fluid to enter the interior chamber 32 of the filter unit 22.
Although shown in partial cross-section, the filter unit 22 may include apertures 70 that may be evenly spaced about the entire circumference of the wall 72 of the filter unit 22.
The fluid then flows through the filter 26, through the hollow core 36 and exits the filter unit 22 through the outlet 34.
In the embodiments depicted in Figure 1 and Figure 2, an indicator is attached to the receptacle 24. The indicator is adapted to visually indicate to a user that the filter element 26 should be removed and replaced with a new filter element. Although a variety of indicators may be utilized with the present invention, selected embodiments may include the indicator 40 that is shown in Figures 1-7. In the embodiments depicted therein, the indicators may be symmetrical about the plane through which the cross-section has been taken. The indicator 40, depicted in Figure 1, may include a first reservoir 42 which is in fluid communication with the interior chamber 32 of the receptacle 24 via a passageway 43, which is best seen in Figures 3-7.
A first flow restrictor 44 may be positioned within the passageway 43 of the first reservoir 42 so that the first flow restrictor 44 is positioned between the first reservoir 42 and the interior chamber 32 of the receptacle 24. The first flow restrictor 44 restricts the amount of fluid which may enter the first reservoir 42. The first flow restrictor 44 may be formed of a membrane such as an apertured film, a nonwoven or woven fabric or web, a rolled or crumpled nonwoven plug similar to a cigarette filter, ceramic, or the like.
Additionally, the flow restrictor 44 may be formed from and integral with the receptacle 24.
In such an embodiment, the passageway 43 may include a single pore or aperture, or a plurality of pores or apertures which adequately restrict the flow of fluid from the interior chamber 32 of the receptacle 24 into the first reservoir 42.
In particular embodiments, the first flow restrictor 44 provides greater resistance to flow than the filter element 26. Thus, only a small portion of the fluid flowing into the inlet 14 may be diverted to the first reservoir 42. In some embodiments, 95% to 99.999% of the fluid flowing into the inlet 14 exits the filtration system 10 through outlets 34 and 18. Any given range presented herein is intended to include any and all lesser included ranges.
For example, a range of from 45-90 would also include 50-90; 45-80; 46-89 and the like.
Thus, the range of 95% to 99.999% also includes, for example, the ranges of 96% to 99.1 %, 96.3% to 99.7%, and 99.91 to 99.999%. .
The quantity of fluid that may be contained within the first reservoir 42 may be selected so that, when the fluid in the first reservoir 42 reaches a predetermined level, the amount of fluid in the first reservoir 42 provides a visual indication to the user that the filter element 26 should be replaced with a new filter element. In alternate embodiments, the first reservoir may be farmed of a material that interacts with either the fluid entering the first reservoir or the fluid within the reservoir once such fluid has reacted with the dye.
This interaction causes the material to change appearance ~so as to alert a user that the useful life of the filter has been reached.
In some embodiments, all or a portion of the housing 12 may be formed of a translucent or transparent material. In the embodiment depicted in Figure 1, the housing 12 further includes a window 39 which may be formed of a transparent or translucent material. The window 39 is positioned so that the first reservoir 42 is visible to a user.
A second reservoir 46 may be further included in the indicator 40. As best seen in Figures 2 - 7, the second reservoir 46 is in fluid communication with the first reservoir 42 via a passageway 47. In selected embodiments, the second reservoir 46 is positioned with respect to the first reservoir 42 so that fluid may not enter the second reservoir 46 until the fluid within the first reservoir 42 has risen to a predetermined level. This may be accomplished by directing the flow into the first reservoir 42 so that fluid entering the first reservoir does not flow or splash into the second reservoir 46. In such an embodiment, a portion of the fluid within the first reservoir 42 will flow into the second reservoir when a sufficient amount of fluid has entered the first reservoir 42. Thus, in some embodiments, when the level of fluid within the first reservoir 42 has provided a visual indication to a user that the filter element 26 should be replaced, the fluid has reached a sufficient height within the first reservoir 42 to enter the second reservoir 46.
In selected embodiments, a second flow restrictor or barrier 48 may be positioned at the passageway 47 of the second reservoir, the second flow restrictor or barrier 48 being thus disposed between the second reservoir 46 and the first reservoir 42. The second flow restrictor or barrier 48 may restrict the amount of fluid that enters the second reservoir 46. The second flow restrictor or barrier 48 may be formed of a membrane such as an apertured film, a nonwoven or woven web or fabric, a rolled or crumpled nonwoven plug similar to a cigarette filter, ceramic, or the like.
Additionally, the second flow restrictor or barrier 48 may be formed from and integral with the receptacle 24. In such an embodiment, the passageway 47 may include a single pore or aperture, or a plurality of pores or apertures which adequately restrict the flow of fluid from the first reservoir 42 into the second reservoir 46.
In particular embodiments, a dry, water-soluble colored dye 52 may be disposed within the second reservoir 46. The dye may be in the form of a powder or a pellet or other similar shape, or may be contained within a fluid-permeable container.
The second flow restrictor or barrier 48 may be utilized to retain the dye 52 within the reservoir 46.
Alternately, the dye powder, pellet or container may be of sufficient size so that it may not pass through the second flow restrictor or barrier 48, or the passageway 47.
The dye 52 may be composed of a non-toxic or edible dye so that no potentially detrimental health effects could result from ingestion or use of the dye 52.
In such a system, as fluid enters the second reservoir 46 through the second flow restrictor or barrier 48, the dye 52 dissolves in such fluid. This colored fluid may then flow back through the passageway 47, the second flow restrictor or barrier 48 and into the first reservoir 42 where it may be seen by a user. The color change in the fluid present within the first reservoir may be utilized to provide an additional indication to the user that the filter element 26 should be changed.
To assure proper fluid flow through the filtration system 10, vents may be variously positioned in the filtration system 10. Such vents prevent air from being trapped within portions of the filtration system, thereby preventing fluid from entering such portions.
Vents 50, which are best seen in Figures 2 - 7, may be positioned on the upper portion of the indicator 40, permitting venting of the first and second reservoirs 42 and 46, respectively. Although one vent may be utilized to vent both reservoirs, separate vents may be positioned in each reservoir.
In other selected embodiments of the present invention, an electrical indicator andlor sound-generating device may be utilized in conjunction with the first andlor second reservoir. In such a system, electrical contacts are positioned within the reservoir, and a power source such as a battery is provided. When the fluid has reached a particular level, the fluid touches the electrical contacts, closes an electrical circuit, and the power source drives the electrical indicator and/or sound-generating device. Such circuitry is commonly known, and an example of such circuitry is described in U.S. Patent No.
5,458,766 to Ehara et al., which is hereby incorporated by reference.
A visual indicator such as, for example, an LED or LCD may be included in such an electrical circuit. Upon completion of the circuit, the visual indicator would display an appropriate message or symbol indicating that the filter element 26 has reached the end of its useful life and should be replaced.
The sound-generating device may be positioned within or attached to the housing 12. The sound-generating device may be electrically connected to the circuit so that, upon completion of the circuit, the sound-generating device emits a tone, buzz, voice or other sound. Such a sound or visual indication may be controlled by the circuitry so that the sound or visual indication is intermittent or continuous, and may vary depending upon the length of time the circuit has been completed. In selected embodiments, a sound or visual indication may be generated for a brief period of time when the circuit is initially activated, and may be reactivated to sound again or provide an additional visual indication each time the filter is subsequently used.
In one example of such a system which may be utilized in the present invention, a power source, such as a battery, and a sound-generating device may be positioned within or mounted to the housing 12. The power source and sound-generating device may be in electrical communication with housing contacts 64 and 66 which, as shown in Figure 1, are positioned in the housing 12. Electrical contacts 56 and 58 may be positioned on the exterior of the receptacle 24. Upon engaging the receptacle 24 to the housing 12, the filter unit electrical contacts 56 and 58 engage the housing contacts 64 and 66.
As best shown in Figures 2 and 7, the electrical contacts 60 and 62 are spaced apart from each other and are positioned within the second reservoir 46. The contacts 60 and 62 are in electrical communication with electrical contacts 56 and 58 which are positioned on the exterior of the receptacle 24. As the filter element 26 approaches the end of its useful life, fluid has filled the first reservoir 42 and enters the second reservoir 46. The fluid within the second reservoir 46 dissolves the dye 52 and, when a sufficient amount of fluid is present within the second reservoir 46, the fluid electrically connects the contacts 60 and 62 thereby closing the circuit and activating the usual indicator andlor sound-generating device. In addition, an additive such as a ionic solute may be added to the fluid within the first reservoir to enhance the electrical conductivity of such fluid. In some embodiments, the ionic solute may be added to the dye 52.
The embodiment depicted in Figure 3 includes housing 12 having an inlet 14, a flow chamber 16, and an outlet 18. The filter unit 22 may include the filter element 26 which is adhered to the lid 20. The lid 20 includes a lip 76 which engages a shoulder 78 positioned on the housing 12. In this embodiment, the lid 20 functions as the cover 18 in previously discussed embodiments, as the lid 20 prevents fluid from entering the hollow core 36 of the filter 26 without passing through a particular amount of filter material. The lid 20 may be adhered to the filter element 26 in a variety of ways, such as, for example, by adhesive.
A gasket 27 may be disposed between the bottom of the filter 26 and the interior surface of the housing 12. As the lid 20 is engaged to the housing 12, the gasket 27 is urged against the bottom surface of the interior of the housing 12. The gasket 27 inhibits fluid from flowing between the filter element 26 and the bottom surface of the interior of the housing 12. When the filter element 26 has reached the end of its useful life, the filter unit 22 is removed from the housing 12. A new filter unit 22 which includes a new filter element 26 may then be engaged to the housing 12.
In the embodiment depicted in Figure 3, the indicator 40 includes a threaded end which removably engages a threaded opening in the housing 12. Upon engagement of the indicator 40 to the housing 12, fluid may flow from the flow chamber 16 to the firsf and second reservoirs 42 and 46, respectively. Seals and/or sealing materials may be positioned about the threaded opening to prevent fluid from leaking out of the housing 12 around the threaded opening. In such an embodiment, the filter element 26, lid 20, gasket 27 and indicator 40 are removed and replaced when the filter element 26 has reached the end of its useful life.
Figure 4 depicts another embodiment of the filtration system according to the present invention wherein the indicator 40 is integrally formed with the lid 20. The lid 20 threadably engages the housing 12. A gasket 21 inhibits the flow of fluid around the threads. The filter element 26 may additionally be attached to the lid 20, as described above. When the useful life of the filter element 26 has been reached, the lid 20, indicator and filter element 26 are removed and replaced.
Figures 5, 6 and 7 are alternate configurations of the indicator 40. Figure 5 includes a second reservoir 46 that is spherically shaped. The dye pellet 52 is contained therein and prevented from contacting the fluid until the fluid within the first reservoir 42 35 has reached a sufficient height and enters the second reservoir 46. The flow restrictor or barrier 48 may be placed proximate to the passageway 47 to prevent fluids which are flowing from the passageway 43 into the first reservoir 42 from inadvertently entering the second passageway 46.
An alternate embodiment of the indicator 40 is shown in Figure 6. The indicator shown therein includes an alternate configuration of the second reservoir 46.
The second reservoir 46 is shaped as an inverted "U", the dye 52 being positioned in the recess formed by the rightmost leg of the "U". As also shown in Figure 6, a wall 82 forms a fluid-impervious barrier between the first and second reservoirs 42 and 46, respectively. The wall 82 assists in directing fluid flowing into the first reservoir 42 away from the second reservoir 46, but does not inhibit fluid within the first reservoir 42 from entering the second reservoir 46 when the fluid level within the first reservoir increases. As depicted in Figure 7, contacts 60 and 62 are positioned within the second reservoir 46.
Figure 7 depicts another embodiment of the indicator 40, the dye 52 being positioned in a recess formed in the lower portion of the second reservoir 46.
In certain embodiments, the filtration system 10 should be oriented in a particular, fixed position to ensure proper flow of fluid into the first reservoir. This would also assist in preventing inadvertent flow from the first reservoir to the second reservoir.
While the invention has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to and variations of the embodiments disclosed herein. Such alterations and variations are believed to fall within the scope and spirit of the present invention and the appended claims.

Claims (8)

1. A filter unit suitable for use in a filtration system, the filter unit comprising:
a receptacle having an inlet, an interior chamber, and an outlet;
a filter element positioned within the interior chamber of the receptacle, the filter element and receptacle adapted to permit fluid flowing into the inlet of the receptacle to enter the interior chamber of the receptacle, pass through the filter element, and exit the receptacle through the outlet; and an indicator having a first reservoir in fluid communication with the interior chamber of the receptacle, at least a portion of the first reservoir being visible to a user, and a first flow restrictor positioned between the first reservoir and the interior chamber of the receptacle.

2. The filter unit of claim 1, the filter element including a material selected from the group consisting of block activated carbon, granular activated carbon, membranes, woven fabrics, and nonwoven fabrics.

3. The filter unit of claim 1, the indicator further including:
a second reservoir in fluid communication with the first reservoir;
a second flow restrictor positioned between the second reservoir and the first reservoir; and a water-soluble dye disposed within the second reservoir, the second reservoir being positioned with respect to the filter unit so that, as the fluid in the first reservoir reaches a predetermined level, the fluid enters the second reservoir through the second flow restrictor, the water-soluble dye dispersing in the fluid and flowing out through the second flow restrictor.

4. The filter unit of claim 3, the filter element including a material selected from the group consisting of block activated carbon, granular activated carbon, membranes, woven fabrics, and nonwoven fabrics.

5. A filtration system comprising:
a housing having a housing inlet, a flow chamber in fluid communication with the housing inlet, and a housing outlet;
a filter unit positioned at least partially within the housing, the filter unit having a receptacle having an inlet in fluid communication with the housing inlet, an interior chamber, and an outlet in fluid communication with the housing outlet;
a filter element positioned within the interior chamber of the receptacle, the filter element and receptacle adapted to permit fluid flowing into the inlet of the receptacle to enter the interior chamber of the receptacle, pass through the filter element, and exit the receptacle through the outlet; and an indicator having a first reservoir in fluid communication with the interior chamber of the receptacle, at least a portion of the first reservoir being visible to a user, and a first flow restrictor positioned between the first reservoir and the interior chamber of the receptacle.

6. The filter unit of claim 5, the filter element including a material selected from the group consisting of block activated carbon, granular activated carbon, membranes, woven fabrics, and nonwoven fabrics.

7. The filter unit of claim 5, the indicator further including:
a second reservoir in fluid communication with the first reservoir;
a second flow restrictor positioned between the second reservoir and the first reservoir; and a water-soluble dye disposed within the second reservoir, the second reservoir being positioned with respect to the filter unit so that, as the fluid in the first reservoir reaches a predetermined level, the fluid enters the second reservoir through the second flow restrictor, the water-soluble dye dispersing in the fluid and flowing out through the second flow restrictor.

8. The filter unit of claim 7, the filter element including a material selected from the group consisting of block activated carbon, granular activated carbon, membranes, woven fabrics, and nonwoven fabrics.