Field of the Invention

The present invention relates to a water container for removing impurities from water to provide sterile safe drinking water, and in particular relates to a hydration pack comprising a hydration bladder with water filter.

Background to the Invention

For those engaged in active outdoor pursuits who require drinking water it is common for such people to carry their own supply of water with them. Although it may be the case that there is no other source of water available en route, it is also true to say that they are unwilling to stop and drink from an open, untreated water source because of the risk of contamination. A popular solution to this problem has been to provide a water bladder, often with a drinking tube and mouthpiece attached, and known as a personal hydration pack. The water bladder can be placed inside existing baggage such as a rucksack, and the tube and mouthpiece essentially act as a straw-the user takes the mouthpiece into the mouth and sucks in order to extract water from the bladder. A typical mouthpiece includes a bite valve to control the flow of water and a locking valve to isolate the bladder from the mouthpiece and thereby prevent leakages.

A locking valve is necessary because the bite valve is not sufficiently effective to be relied upon at all times. There is small but significant loss of water while the locking valve is open, even if the bite valve is closed. This is because by the act of simple motion and/or the bite valve banging against other objects a small amount of water is let by. Over time, the bite valve also wears through constant biting.

Although personal hydration packs have proven to be a great advance over traditional water bottles, they do suffer from some drawbacks. In particular, it is often difficult for the user to quickly draw an acceptable flow of water from the bladder. It should be understood that every breath the user spends drawing water from the bladder is one less breath that can be used to deliver oxygen to the user's body.

A further complication arises when the water in the bladder needs to be replenished. When the bladder is placed in a rucksack, for example, the user will be required to remove the rucksack, extract the bladder, and remove the bladder closure (typically a screw fitting or clip) before refilling it with water. In practice, a number of other steps are required, for example it is often necessary to remove the drinking tube and the mouthpiece. Hydration packs are now commonly used by soldiers, who require drinking water while operating in hostile environments. Clearly, removing the soldier's backpack and then extracting the bladder in order to place it in an available water source, such as a river or a stream, puts the soldier in a vulnerable position. On the other hand, it may often be necessary for the soldier to scavenge for water in such available water sources.

Users generally also face the problem of the water heating up inside the bladder and in the drinking tube, making the water extremely unpalatable to drink. It is known to address this problem (with limited success) by enclosing the bladder and drinking tube in an insulating sleeve.

Users often use the water to cool themselves down. Conventional extraction of water from hydration packs for this purpose, unless it is drawn directly into the mouth is cumbersome. The user must hold the bite valve below the level of the water inside the bladder, squeeze the bite valve by hand and empty some water onto his or her hand or head etc. It will be understood that this can be quite a wasteful use of water.

Some known hydration packs include water filters for removing impurities to provide sterile safe drinking water. An example is described in WO2010/038015A1. However, the structure and configuration of such packs do not always ensure optimum filtration and extraction of the water in the pack, nor best use of space. As such, there is a need for an improved hydration pack. Summary of the invention

According to a first aspect of the present invention, there is provided a hydration pack comprising:

a rigid hydration bladder for holding water, said bladder having a vertical extent between a top region and a bottom region, and having a horizontal extent between two side walls;

a fluid inlet coupled to the hydration bladder for filling the bladder with water from a source;

a fluid outlet for extracting water from the bladder; and,

a water filter coupled to the bladder and to the fluid outlet, the water filter comprising one or more membranes which are effective to pass water in preference to air under the influence of a pressure differential,

wherein the water filter is disposed proximate the bottom region of the bladder and distal the top region of the bladder, and

wherein the water filter extends in the horizontal direction, whereby to maintain maximum contact with water in the bladder as water is extracted via the fluid outlet.

The present invention provides a hydration pack comprising a hydration bladder with a very effective water filter for removing impurities. In contrast with known hydration bladders, the hydration bladder of the present invention is rigid, in that it is self- supporting and able to retain its form and volume as it is filled with water and emptied of water. Moreover, compared to some other known hydration bladders, the rigid hydration bladder of the present invention is better able to withstand pressurization to create the desired pressure differential and facilitate water extraction from the bladder. However, although rigid in this regard, the hydration bladder may still flex a little around its usual static shape, with the degree of flex being dependent on the material from which it is formed, and also on the structural shape and thickness of the bladder. In the present invention, the hydration pack is designed to be used in an orientation with the vertical extent generally perpendicular to the ground and the horizontal extent generally parallel to the ground. The water filter is located near to the bottom of the pack, so as to ensure optimum contact with water in the bladder as water is removed from the bladder. In particular, the water filter is positioned adjacent a lower region of the bladder (or within that lower region) and oriented such that the filter extends transversely across the bladder, thereby ensuring optimum contact with water stored above it. Consequently, the membranes of the filter typically extend over the same transverse extent. However, although designed for operation in a vertical orientation, the hydration pack operates well if the pack is tilted from the vertical towards the horizontal plane, such that the vertical extent of the hydration bladder is oriented at an angle to the perpendicular to the ground. Likewise, the pack operates adequately if tilted such that the horizontal extent is not parallel to the ground.

The fluid outlet of the hydration pack is coupled to the water filter, and is preferably disposed proximate the bottom region of the hydration bladder and distal the top region of the bladder. More preferably, the fluid outlet is located at one side wall of the rigid bladder adjacent one end of the filter. Preferably, the filter is removable from the hydration pack, thereby facilitating replacement. The fluid outlet may then be removeably attached to an end of the water filter, and may form part of the mechanism by which the filter is secured in place. Preferably, the fluid outlet is provided with an activated carbon filter, which acts as final filter stage after ultra-filtration by the primary water filter and serves to improve the taste of the filtered water.

Preferably, the fluid inlet is disposed proximate the top region of the hydration bladder and distal the bottom region of the bladder. More preferably, the fluid inlet is located on an upper surface of the hydration bladder joining the two side walls. In one preferred embodiment, the fluid inlet is located on the upper surface adjacent one of the side walls. This is a convenient location for attaching tubing to fill the bladder with unfiltered water. The fluid inlet to the hydration bladder may be provided with a removable closure to allow the bladder to be filled in a conventional manner rather than be filled via a pump coupled to the fluid inlet. The fluid inlet may also comprise a non-return valve to prevent pressurized water from escaping via the inlet when the filling tube is not attached.

In the present invention, the water filter comprises one or more membranes which are effective to pass water in preference to air under the influence of a pressure differential. Preferably, it comprises at least one hydrophilic membrane. Hydrophilic membranes are attractive to water and therefore water is passed through them in preference to other liquids and to gases. In this way, not only is the filtration offered by the preferred embodiments improved, but it is possible to use the filter even when it is not completely immersed in the liquid. Preferably, the membranes are capillary hollow fibre membranes. These membranes act to filter the water as only particles smaller than their pore size may pass through them. The fibre membranes may incorporate carbon or other chemical elements, or reverse osmosis membranes. A combination of different types of filter membranes may be included in the filter. These may include ultrafiltration, nanofiltration and reverse- osmosis membranes.

In a preferred embodiment, the water filter comprises a filter cartridge comprising a plurality of hollow fibre membranes, which are effective to pass water in preference to air under the influence of a pressure differential which drives or draws water through the membranes. A suitable form of water filter cartridge is described in International patent application number PCT/GB2007/003623 (International publication number WO2008/037969) filed on 25 September 2007. Filter cartridges of this type have a mean pore size which is capable of ultra-filtration and are thereby effective to remove viruses as well as bacteria from the water.

Preferably, the fibre membranes are bundled into a filter cartridge having a form factor suited to that of the rigid hydration bladder. Typically, this will be substantially rectangular in cross-section. Preferably, the water filter furthers comprise a carbon filter sleeve disposed around the bundle of fibre membranes. The carbon filter sleeve will typically comprise a carbon fabric and will act as a pre-filter, filtering out radioactive isotopes such as iodine-131 .

Preferably, the hydration pack is adapted to prevent movement of the water filter therein, which may place strain on the filter membranes. In preferred embodiments, the rigid hydration bladder comprises internal projections adapted to resist movement of the filter. The projections may correspond to indentations in outer surfaces of the hydration bladder. It is further preferred that a sump region is provided below the water filter to collect detritus that settles to the bottom of the hydration pack past the water filter. The sump region may be provided by projections from a bottom wall of the hydration bladder, with the filter resting against the bottom wall between the projections. Equivalently, the filter rests against indentations in a bottom wall of the hydration bladder, with the space between the indentations acting as a sump. The indentations may also serve to accommodate a carrying strap, which passes around the hydration pack.

The hydration pack may also include means for establishing the pressure differential, which may be formed integrally with the rigid hydration bladder. Alternatively, the pressure differential establishment means may be external to the bladder and detachable therefrom. Preferably, the pressure differential establishment means comprises a pump in communication with the water containing region of the hydration bladder. If external, the pump will typically be coupled to the fluid inlet. The pump may be powered, but is preferably manually operated. If manually-operated and integrated within the hydration bladder, the pump may comprise a manually-operated piston disposed vertically adjacent one of the side walls of the hydration bladder. The fluid inlet may then be disposed near to the opposing side wall.

Preferably, the pump is operative to pressurise the hydration bladder with air, whereby to urge water through the water filter to the fluid outlet. A pressure of greater than 1 -2 bar may be applied. The pump may be operative to draw water into the hydration bladder via the fluid inlet under the action of the pump. Preferably, the pump includes a pressure regulator to release pressure when it passes a predetermined threshold value. The pump is preferably capable of creating a pressure up to 5 bar. A suitable pump is described in WO2010/038015A1 . The hydration bladder may include a pressure relief valve which prevents the bladder from becoming over-pressurised.

The hydration pack may comprise both a pump external to the hydration bladder and a pump internal to the bladder. In this case the external pump may be the primary pump for drawing water into the bladder and for pressurizing the bladder. The internal pump may then be used to re-pressurise the bladder as water is withdrawn from it. The hydration pack may comprise chemical means to pressurize the bladder, such tablets that effervesce.

Preferably, the hydration pack further comprises a drinking tube coupled to the fluid outlet, the drinking tube having a bite valve mouthpiece for controlling the flow of water from the hydration bladder. A suitable bite valve is described in WO2010/038015A1 . Thus, the pressure differential provided by a pump can drive or draw water through the walls of the hollow fibre membranes of the water filter and thereafter along the length of the fibre membranes to the mouthpiece when the bite valve is opened. The fluid outlet may comprise a non-return valve to prevent pressurized water from escaping via the outlet when the drinking tube is detached from the fluid outlet.

Preferably, an outer face of at least one of the side walls of the rigid hydration bladder is adapted to removably retain the drinking tube along a length of the side wall. In this way, the drinking tube is safely retained and usefully coveys water towards the top of the hydration pack. It is further preferred that a face of the hydration bladder between the two side walls is adapted to receive the remainder of the drinking tube for storage. For example, a portion of the face may be recessed to receive a section of the drinking tube in a coiled arrangement. Preferably, an outer surface of the hydration bladder is provided with bosses, by means of which webbing may be attached to retain the tubing during storage. Preferably, all edges and external protrusions of the rigid hydration bladder are rounded so as to avoid friction points, which would impede insertion of the bladder into a carrier, such as a day-sack. Some embodiments of the present invention thus provide a hydration pack that includes a pump that is able to act both to transfer water from a source of water into the hydration bladder, and also to pressurise the hydration bladder with air. In other words, it can pump water and it can pump air. As a consequence, unlike with conventional hydration packs the hydration bladder itself need not be physically removed and opened (usually by removing a closure) for filling with water. When the rigid hydration bladder is then pressurised with air, it allows a user to obtain a steady stream of water from the hydration bladder through the bite valve without requiring any suction at the mouthpiece. This has the additional advantage of allowing the user to continue to breathe relatively easily whilst drinking water from the hydration pack.

Preferably, the hydration bladder is formed of a water-grade plastic material, such as polypropylene (PP), polyurethane (PU), medium density polyethylene (MDPE), or polyethylene terephtha!ate (PET). In a preferred embodiment, the hydration bladder is formed of water-grade high-density polyethylene (HDPE). Plastic containers can be made using techniques well known in the art, such as rotational moulding or blow moulding. However, the rigid hydration bladder may be made of other suitable materials, including carbon fibre, composites, and metals. Apart from suitability for use with water, the primary requirements for the material are that the bladder is self-supporting without requiring thick walls that take up valuable space or make or make the bladder too heavy. Typical wall thicknesses may be in the range 0.5-5.0mm, but can be thinner if the material and structural configuration of the bladder provide sufficient rigidity for the bladder to be self-supporting. In some embodiments the hydration bladder may be adapted to receive means to cool or to heat water stored within the bladder. This adaptation may be in place of, or in addition to, an internal pump. For example, the bladder may be adapted to receive an ice-stick for cooling or a heating gel pack for heating. Preferably, the hydration pack incorporates evaporative cooling materials to provide evaporative cooling for the hydration bladder and/or the drinking tube. When these materials are wetted water is adsorbed into the materials. Through the physics of evaporation, heat is drawn from the drinking water in the hydration bladder and the drinking tube through the adsorbent materials to help cool the drinking water. Suitable evaporative cooling materials include cotton, linen, canvas, non-woven synthetic material, Cordura™ from DuPont, cellulose sponge cloth, and other highly adsorbent materials. These materials can be used to encase the hydration bladder and/or the drinking tube. Highly adsorbent gels, such as silica gels, may also be incorporated to further enhance the evaporative cooling effect. Furthermore the drinking tube and the hydration bladder may be made from a thermo-conductive plastic. This makes the evaporative cooling process even more effective.

In preferred embodiments the hydration pack is adapted such that it may be directly attached to a soldiers clothing and to load carriage systems using clips or other attachment devices. For example, the hydration pack may comprise fastening bosses. In particular, it is provided with clips that allow it to be attached to a molle based system incorporating PALS (Pouch Attachment Ladder System), a grid of webbing invented by the United States Army Natick Soldier Research, Development and Engineering Center and used for example in the British Army's Osprey™ body armour. In another example the hydration pack is adapted for use with the Predator series of rucksacks produced by Karrimor SF , such as the Predator TEMAC 50. The hydration pack is then tailored to fit into a space within the daysack that is usually redundant.

In order that the hydration pack does not occupy too much space within personal load carriage systems, it is preferred that a central portion of the rigid hydration bladder is recessed and/or includes cut out sections. It is also preferred that the rigid hydration bladder comprises integrated support ribs for structural integrity. Preferably, one or more sidewalls of the container housing comprise a pattern of indentations to provide enhanced structural rigidity at selected locations, thereby to resist deformation of the sidewalls when under load. Preferably, the bottom region of the rigid hydration bladder is thicker than the top region of the rigid hydration bladder.

In a preferred embodiment, water is primary stored in two vertical columns adjacent the two side walls of the hydration bladder. This arrangement is particularly advantageous for use with personal load carriage systems (e.g. back-pack), as the stored water primarily occupies unusable "dead" space near the side walls of the back-pack either side of the semi-rigid padded back region of the back-pack. A limited amount of water is still stored in the one or more thin recessed regions or support ribs connecting the two vertical columnar regions. Although providing a fluid connection between the two vertical columnar regions, the thin recessed regions serve to resist water flow between the two columnar regions, thereby preventing water from sloshing about in an uncomfortable manner as the person carrying the back-pack moves around, and the weight distribution of the fluid is largely maintained. Moreover, this configuration ensures optimum contact between water and water filter when the hydration pack is tilted towards the horizontal plane, such as when the person carrying the back-pack bends over or reclines.

In some preferred embodiments an outer face of the rigid hydration bladder between the two side walls is concave so as to better accommodate a back wall of the personal load carriage system (e.g. back-pack) as it flexes around the back of a person carrying the back-pack. Both opposing faces of the hydration bladder may be curved in the same manner.

According to a second aspect of the present invention there is provided a personal load carriage system comprising a hydration pack according to the first aspect. Typically, the personal load carriage system will take the form of a backpack. The dimensions and vertical orientation of the hydration pack make it particularly compatible with various types of backpack design, and the drinking tube can be arranged to pass over the shoulder of the person carrying the backpack for ease of access. The rigid hydration bladder may be located to provide a portion of the load carriage system with structural integrity. In one preferred embodiment, the hydration pack forms an integral part of the load carriage system. The combined load carriage system and hydration pack can then be optimally designed for load storage space, water storage and weight distribution.

As will be appreciated by those skilled in the art, the present invention provides a much improved hydration pack with integral water-filtration system, which is particularly suitable for use in personal load carriage systems. The rigid self-supporting nature of the hydration bladder allows for the inclusion of many innovative and advantageous features.

Brief Description of the Drawings

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of a preferred hydration pack in accordance with the present invention;

Figures 2 and 3 show, respectively, front and rear elevations of the hydration pack shown in Figure 1 ;

Figure 4 shows an end elevation of the hydration pack with secured drinking tube; Figure 5 shows the opposite end elevation of the hydration pack shown in Figure 4; Figure 6 shows a top elevation of the hydration pack, illustrating fluid inlet cap and pump handle;

Figure 7 shows a bottom elevation of the hydration pack shown in Figure 1 ;

Figure 8 shows an exploded perspective view of the preferred hydration pack, illustrating the water filter and internal pump;

Figure 9 is a cut-through perspective view of the preferred hydration pack, showing the internal volume of the hydration bladder and the water filter and pump in situ; and, Figure 10 shows a hydration pack in accordance with the present invention when fitted in a day-sack carried by a soldier. Detailed Description

Figure 1 illustrates a preferred embodiment of a hydration pack in accordance with the present invention. As shown, a rigid bladder 10 made of water-grade high-density polyethylene (HDPE) has a substantially rectangular cuboid shape with two hollow columnar side regions, 1 1 and 12, a bottom region 13 and a thinner top region 14. Much of the central region of the hydration bladder is open, as shown at 20a and 20b, with the two columnar side regions, 1 1 and 12, joined by thinner hollow sections of the bladder, which may comprise integrated support ribs 15b. The top (central) region 15a also serves as a carrying handle with an opening 20a below. The thinner hollow sections in the central region of the bladder 10 provide a fluid connection between columnar side regions, 1 1 and 12, but also serve to restrict the movement of water between these two regions owing to the narrow passage therebetween. This arrangement prevents water from sloshing about inside the bladder when carried, which would otherwise lead to a non-uniform weight distribution and to the stored water gaining momentum undesirably.

The columnar side regions 1 1 , 12 are provide with indentations 16 and protrusions 17 which provide enhanced structural rigidity at selected locations, thereby to resist deformation of the sidewalls when under load. The indentations 16 can also serve to restrict lateral movement of internal components (e.g. a pump) and the protrusions 17 can also serve to retain tubing along the side walls of the bladder 10. The bottom region 13 of the bladder is likewise provided with indentations 18 and 19, which provide enhanced structural rigidity at selected locations, but also serve to locate and restrict lateral movement of the filter cartridge 80 (not shown).

Located on the side wall near the bottom of columnar region 1 1 is a fluid outlet 30, including outlet nozzle 31 . On the upper surface of columnar region 1 1 is a fluid inlet 40, with removable protective cap 41 and inlet nozzle 42. On the upper surface of opposite columnar region 12 is the retaining cap 91 and handle 92 of an internal manual pump 90 (not shown) for pressurizing the bladder 10. Figure 2 shows a front elevation of the hydration bladder 1 1 in which the external structural features, such as the indentations 16, 18, 19 and protrusions 17 are clearly apparent. The indentations 19 at the base of the hydration pack can also serve to locate and restrain carrying straps which pass around and over the pack. Below top carrying region 15a is the elongate opening (or slit) 20a, which comprises two angled wing regions 21 . These may serve to locate and retain the carrying straps, with the straps passing through the opening 20a. The front surface is also provided with threaded fastening bosses 22 for securing items to the bladder. For example, elasticated webbing may be secured to the fastening points 22 so as to retain items carried or temporarily stored in the recessed central portion of the bladder. Other surface features 22 may be purely aesthetic, such as patterns and logos.

Figure 3 shows a rear elevation of the bladder, again openings 20a, 20b are visible, as are side protrusions 17, and lower indentations 18 and 19 for locating and restraining movement of the internal water filter cartridge. Additionally, other surface features 22 may be included, either aesthetic or to receive an informative label.

Figure 4 shows a side elevation of the hydration bladder 10 with a drinking tube 32 attached the nozzle 31 of the fluid outlet 30. The drinking tube 32 snakes between the side protrusions 17 so as to be retained against the side wall of the bladder 10 and emerge at the top adjacent the fluid inlet 40. In a particular example of the hydration bladder, the height from the base to the inlet nozzle is about 420 mm.

Figure 5 shows a side elevation of the opposite side of hydration bladder 10 to that shown in Figure 4. As illustrated, both side walls of the bladder are symmetric as regards the upper indentation and protrusion features, and so a tube could be retained on both sides. However, the lower parts of the two side walls are differently adapted. As shown in Figure 5, on the opposite side wall, the lower indentations 18 are visible. These indentations have corresponding internal protrusions which are spaced apart to accommodate the rear end of the internal filter cartridge and act to restrain vertical movement of the filter cartridge.

Figure 6 shows a top elevation of the hydration bladder 10, with the fluid inlet cap 41 and pump handle 92 clearly visible on either side of the bladder 10. Also visible is the bottom region 13 and the recessed face of thinner top region 14. As illustrated, both the front and rear face of the bladder 10 are slightly curved to accommodate the flexing of a day- sack containing the hydration bladder when worn on a person's back. Figure 7 shows a bottom elevation of the hydration bladder 10, with the location of indentations 19 and the curvature of the front and rear face being apparent. In a particular example of the hydration bladder, the width of the bladder from outer side wall to outer side wall is about 320 mm and the maximum depth of the bladder near the bottom region 13 is about 55mm. Figure 8 shows an exploded view of a hydration bladder 10, in which the component parts of the filter cartridge 80 and manual pump 90 are visible. The filter cartridge 80 is inserted into the bottom region 13 of the bladder via an opening 85 in one side wall of the bladder. Once inserted, a head portion 82 of the filter cartridge is secured to the side wall around the opening 85 with screw or bolts. The fluid outlet assembly 30 is then secured to the head portion 82 of the filter cartridge with further screw or bolts. As shown, the fluid outlet assembly 30 comprises a housing 32 to accommodate an activated carbon filter 33, which provides a final filtration stage between the main filter 80 and the fluid outlet nozzle 31 . The fluid outlet assembly 30 may also comprise a non-return valve to prevent the unintentional release of water when a drinking tube is not attached to the outlet nozzle.

The filter cartridge 80 is preferably of the type described in WO2008/037969A. Filters of this type are made from a matrix of hollow fibre membranes 81 which typically have a mean pore size which is capable of ultra-filtration. As such, the filter cartridge 80 is effective to remove bacteria, viruses, cysts, parasites, fungi and all other water-born pathogens. In fact, such a filter removes all microbiological matter from the water to provide safe, sterile drinking water. In addition, a carbon fabric sleeve may be provided around the bundle of fibre to provide a pre-filter, which is operative to remove radio isotopes such as lodine-131 .

The fibre membranes 81 used in preferred embodiment of the present invention have a retention of greater than log 6 (99.9999%) of bacteria, cysts, parasites and fungi, and greater than log 4 (99.99%) of viruses from the water. The fibre membranes also remove sediments and other deposits from the water. Fibre membranes suitable for use with the present invention are available commercially, for example X-flow (TM) capillary membranes from Norit (www.norit.com) may be used. This hollow fibre ultra-filtration membrane is effective to screen all turbidity, bacteria as well as viruses. Providing a filter cartridge 80 such as that described above allows the user to use water from a wide range of sources, including open sources of water, that is effectively rendered safe to drink. The pump 90 or an external pump can be used to provide the required pressure differential to drive water through the walls of the hollow fibre membranes and thereafter along the length of the fibre membranes 81 to fluid outlet 30. The pump 90 is located vertically in a portion of the columnar side region 12 of the bladder 10 and is held in place by retaining cap 91 . The pump 90 is actuated manually via a pump handle 92, although other forms of pump may be used. The pump handle 92 is attached to the piston head 94 via stem 93, with a ball bearing 95 biased towards the end of the pump head by a spring 96. The piston moves through a piston shaft., such that on the downstroke the pump pressurises the bladder 10 with air, and on the upstroke air is drawn into the pump from outside.

Located above the opposite columnar side region 1 1 of the bladder 10 is the fluid inlet 40 with retaining cap 41 and inlet nozzle 42, which may include a non-return valve. A feed pipe may be connected the inlet nozzle for filling the bladder with unfiltered water. An external inline dual purpose pump may also be connected for pumping or drawing water into the bladder and for subsequently pressurising it. When such an external pump is used instead of an integral internal pump, the cavity occupied by the internal pump can instead accommodate an ice stick for cooling the water or a heating gel pack for warming the water to prevent freezing.

Figure 9 illustrates a vertical section through the bladder 10, which more clearly shows the hollow nature of the bladder and the primary water storage regions 1 1 and 12 at either side of the central region comprising the recessed regions 15a and 15b and openings 20a and 20b. The in-situ filter cartridge 80 with fibre membranes 81 is apparent in the bottom region 13 of the bladder. Also clear are the internal protrusions corresponding to external indentations 18 and 19, which serve to locate the filter cartridge 80 and resist its vertical movement. Furthermore, Figure 9 clearly shows the hollow regions 86 located at the bottom of the bladder 10 on either side of indentations 19. These hollow regions 86 usefully act as sump to collect detritus in the unfiltered water, which sinks to the bottom of the bladder past the sides of the filter cartridge 80. Finally, Figure 9 shows the manual pump 90 located in an upper part of side region 12, with the piston mechanism clearly visible.

Figure 10 shows a hydration pack 100 in accordance with the present invention located inside a day-pack 101 worn by a soldier 102. The hydration bladder 10 sits against the wall of the day-pack closest to the soldier's back. The central recessed portion of the hydration bladder 10 receives the semi-rigid padded back portion of the day-pack, while the primary columnar water storage regions 1 1 and 12 are located in the unusable "dead space" at either side. With such an arrangement, the hydration pack can occupy only 6% or less of the storage space within the day-pack. Indeed, when the unusable nature of some of this space is taken into account, the hydration pack can occupy only 4% or less or the usable storage space, whilst providing 3 to 3.5 litres of water storage capacity. As shown in Figure 10, the hydration pack 100 includes a drinking tube 103 attached to the fluid outlet and a feed tube 104 attached to the fluid inlet. Both of these are stowed neatly and can pass over the soldier's shoulder for ease of access.

In a preferred embodiment the drinking tube 103 is connected by a suitable connector to a bite valve with mouthpiece of the type described in WO2010/038015A1 . In order to drink from the hydration pack 100, the user merely bites down on the mouthpiece to open a bite valve within, which then releases a stream of filtered water from the bladder 10 without needing to suck the mouthpiece. The mouthpiece may also include a user activated spray head, such that pressure within the bladder 10 releases a spray of water when the spray head is activated. This is particularly useful should the user wish to use water stored in the bladder 10 for cooling their body.

The bite valve seals the mouthpiece effectively, thereby negating any requirement for additional locking valves that must be actuated separately. Moreover, the bite valve is able to cope with the potential pressure in the bladder without leaking. In use, the positive pressure differential that exists in the bladder upstream of the mouthpiece also reduces the risk of contamination as it prevents microbiological contamination being drawn back into the mouthpiece, down the drinking tube 103 and back into the hydration bladder 10. In another preferred embodiment the feed tube 104 is connected to an external pump, which in turn is connected to a scavenging hose. A pre-filter may be fitted at end of the scavenging hose. This external pump may be provide instead of an integral pump built into the bladder or else to supplement it . A suitable dual-purpose mechanical pump and scavenging hose is also described in WO2010/038015A1 . In use, one end of the scavenging hose is immersed or otherwise coupled to a source of water and the pump may then be used to pump water from the source into the bladder 10 via the scavenging hose, the pump, and the feed tube 104. The use of the pump to fill the bladder means the user does not need to remove the bladder from its storage position (for instance, on the user's back) in order to fill it with water.

The external pump is provided with non-return valves at the input and output ports. When the pump head is withdrawn the pressure differential created is sufficient for a non-return valve associated with the input port to be displaced to let fluid pass into the pump chamber. When the pump head is returned up the pump chamber the return valve at the input port closes, while a non-return valve associated with the output port is displaced to allow fluid to pass out of the pump chamber. Once the bladder has been pressurised with air by the pump, the associated pressure differential is effective to bias the non-return valve at the output port closed. It will only open when the pump is actuated to overcome this bias. When the scavenging hose is removed from the water source, continued operation of the pump pumps air into the bladder 10 to increase the internal pressure. The pump, therefore, can be used both to fill the bladder with water and subsequently to pressurise it with air.

In a particularly preferred embodiment, the external pump has a substantially rectangular form factor and comprises two detachable parts, a manifold and a pump mechanism. The manifold has the inlet and outlet for connecting, respectively, to the scavenging hose and filling hose, and is also adapted to connect to corresponding portions of the detachable pump mechanism. In this way, the manifold can be clipped on to a front strap of the soldier's day-pack 101 and remain there connected to the filling house 103, and possibly to the scavenging hose which is stored in the pack. The pump mechanism can be connected to the manifold for the purpose of pumping water into the hydration bladder and for pressurising it. Afterwards, the pump mechanism can be detached from the manifold and stored safely elsewhere. A slim rectangular form factor for the two-part pump ensures it is light and unobtrusive on a soldier's webbing when in use. The pump mechanism then takes the form of a detachable cartridge. Preferred embodiments of the present invention also address the issue of controlling water temperature. Particularly in hot climates, water within the bladder and drinking tube is heated to the extent that it can become unpalatable. It may also increase the rate of bacteriological growth within the bladder. There is a need to find a solution to help keep the water cool.

In preferred embodiments the hydration pack incorporates evaporative cooling materials to provide evaporative cooling for the hydration bladder 10 and/or the drinking tube 103. Suitable evaporative cooling materials include cotton, linen, canvas, non-woven synthetic material, Cordura™ from DuPont, cellulose sponge cloth, and other highly adsorbent materials. A layer of these materials can be used to cover the wall of the hydration bladder 10 and/or the wall of the drinking tube 103. Furthermore, a layer of highly adsorbent gel, such as silica gels, may also be incorporated to further enhance the evaporative cooling effect. Furthermore the hydration bladder 10 and the drinking tube 103 may be made from a thermo-conductive plastic. This makes the evaporative cooling process even more effective. When these evaporative cooling materials are wetted, water is adsorbed into the materials. Through the physics of evaporation, heat is drawn from the drinking water in the hydration bladder and the drinking tube through the adsorbent materials to help cool the drinking water. The feed tube 104 and/or the drinking tube 103 may contain activated carbon and ion exchange resins. These may be in the form of powder or compressed into spheres. These spheres may vary in size so as to allow greater flow of liquid through the interstitial space between the spheres. These spheres may run the entire length of the tube or they may only partially occupy the tube. They are designed to reduce/remove various chemical contaminates. The ion exchange resin is designed to remove salts, and other chemicals present in the water. Such a tube may be replaced when it has expired.

The present invention thus provides an effective hydration pack with self-supporting hydration bladder and integral water ultra-filtration system. The pack is particularly well suited for use in personal load carriage systems, such as day-packs, by virtue of the design freedom afforded by the rigid bladder, which permits best use of "dead space" within the day-pack. Moreover, the hydration pack may be provided with a range of innovative and advantageous features which complement and cooperate with the fundamental elements of the invention.