Abstract:
The invention described herein includes a latrine pan and collector system for use in an offset pit latrine. The system permits use of a latrine pan having a flapper in an offset leach pit context, and eliminated the necessity of large scale installation of a concrete collection box, which can collect unsanitary debris. The system of the invention includes (1) a pour-flush latrine pan and (2) a collector. The collector includes a collector body that engages the latrine pan, defines a discharge opening, and secures an inclined surface sloping downwardly between an impact zone positioned beneath the outlet of the latrine pan and the discharge opening, the collector body securing the inclined surface at a position sufficiently distant from the underside of the latrine pan so that the inclined surface does not impede pivoting of the flapper, whereby material discharged from the outlet of the latrine pan contacts the inclined surface at the impact zone and slides downwardly from the impact zone to the discharge opening. 
     Also included is the collector described above, related latrine structures and methods.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) to each of U.S. Provisional Patent Application No. 61/858,838, filed Jul. 26, 2013 and U.S. Provisional Patent Application No. 61/949,626, filed Mar. 7, 2014, each entitled “Collection Systems for Use in Offset Pit Latrines Having Pour-Flush Latrine Pans, Collectors, Offset Pit Latrines, and Related Methods,” the disclosures of each of which are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    It is reported that about 2.5 billion people worldwide do not have access to any type of improved sanitation facility. These individuals suffer significant adverse health effects, including death, as a direct result of a lack of improved sanitation, including lack of sanitary toilet facilities. Diarrheal diseases resulting from lack of sanitation are the second leading cause of child deaths in the world, claiming over 700,000 lives per year. The most affected are individuals residing in developing countries, often living in conditions of poverty outside of city centers. Such individuals do not have regular and easy access to a running fresh water supply or to facilities for the sanitary disposal of human excreta. 
         [0003]    Because of the very real dangers posed by poor sanitation, the United Nations included access to improved sanitation as part of the Millennium Development Goals (MDGs) established at the Millennium Summit in 2000. Specifically, Goal 7, Target 7c of the MDGs aspires to reduce by half the proportion of people without sustainable access to basic sanitation by the year 2015. “Basic sanitation” requires access to facilities that hygienically separate human excreta from human contact, such as toilets with sewer connections and septic system connections, where feasible, or pour-flush and covered slab latrines in more remote areas. 
         [0004]    Traditional, open pit latrines, bucket latrines, and hanging latrines do not meet the criteria of basic or improved sanitation, in part because the hygienic separation of the actual waste products from human contact is not ensured, and also because of the unregulated and uncontrolled release of various sewage-generated gases from these types of latrines. Gases emitted from the decomposing human waste in a leach pit pose, at minimum, an olfactory challenge, as their odor is unpleasant. Of greater significance are the potential adverse health effects of longer term exposure to the sewage gases, in particular to methane, hydrogen sulfide, and ammonia. Exposure to these gases, even in low levels over the long term can result in chronic mucus membrane irritation, cause chronic coughing or sore throat, shortness of breath, and fluid accumulation in the lungs. Other effects may include fatigue, pneumonia, loss of appetite, headaches, irritability, poor memory, and dizziness. At very high concentrations (&gt;300 ppm), hydrogen sulfide can cause loss of consciousness and death. 
         [0005]    Pour-flush latrines are considered by the UN and the World Health Organization to be suitable, improved sanitation facilities in warmer weather locales where water or sullage is readily available, but sewer pipes and plumbed in toilet facilities are not. Pour-flush latrines are advantageous as compared to ventilated pit latrines in that they can be fitted with a water seal or “trap” that prevents flying insects form entering the pit, thereby blocking transmission of pathogens. 
         [0006]    Pour-latrines require a low water volume (typically, 1-3 liters per “flush”), are suitable in cultures where anal cleansing traditions are prevalent, require minimum maintenance, can be sited in family residences and operated using sullage (as opposed to fresh water), effectively solving two problems (proper excreta and sullage disposal) with one device. 
         [0007]    In most latrines, including pour-flush latrines, once the excreta is delivered to the leach pit, it is degraded by aerobic and anaerobic means, and will necessarily generate a variety of gases, many of which smell unpleasant, and some which are harmful to one&#39;s health. 
         [0008]    When constructing a pour-flush latrine, many organizations advocate use of pour flush latrines having “offset leach pits” (“offset pit latrines”) where cultural and social norms permit, and where there is sufficient land available. An offset pit latrine is one in which the leach pit, instead of being built directly below the latrine opening (i.e., below the point of entry of the waste material), is built at a distance from (“offset from”) the latrine opening. A schematic of a prior art offset pit latrine A is shown in cross section is provided in  FIG. 1 . As can be seen, the offset pit latrine is designed on the principle that waste which enters the squat pan B will travel though the pipe C to the leach pit D. 
         [0009]    The offset pit latrine in principle may provide several advantages over latrines having leach pits built directly under them. For example, during use, the leach pit itself will contain a potentially rapidly accumulating amount of human waste; use of an offset leach pit permits the users to site the accumulated waste outside the dwelling while permitting the squat room itself to remain within the dwelling. In general, offset pits allow for the construction of a more elaborate, permanent structure around the latrine, as the access point for eventual emptying of the pit is moved outside of the shelter. 
         [0010]    Leach pits eventually fill up and must be emptied or allowed to lie fallow until the waste has degraded. Use of offset leach pit allows for connection of the squat room facilities with more than one leach pit, so that waste can be diverted to an empty pit, once a first pit becomes full. This may be advantageous as the contents of the first pit can be allowed to degrade/compost over the time period in which the second pit is in use. Upon filling of the second pit, which should take about a year or more after the filling of the first pit, the waste in the first pit will be composted and relatively safe to remove.  FIG. 2  shows a schematic plan view of an offset pit latrine A connected to two offset leach pits D1, D2. Use of the first pit D1 or the second pit D2 can be regulated by use of a diverter box E (shown in  FIG. 2 ) or by redirection of the connecting ducts or pipes (not shown). 
         [0011]    However, conventional offset pit latrines still suffer several drawbacks. In an attempt to prevent transmission of sewer gases and/or flying insects between the leach pit and the squat room (and therefore the dwelling), conventional offset pour flush latrines generally utilize one of two practices. The first is to provide a squat pan having at its outlet a gooseneck or flap that is designed to block transmission of gases or insect (see  FIG. 3 , reference letter H) by maintaining a water seal F. The gooseneck pan G is usually installed over a collection box that is in fluid communication with the offset leach pit. Generally, the collection box is formed from cement or concrete at the time the latrine is constructed. 
         [0012]    The disadvantages to this configuration are several-fold: (1) the gooseneck outlet of the squat pan and/or the surfaces of the collection box tend to become blocked or obstructed with paper or other objects used for anal cleaning by the latrine user; (2) even if cleaning objects are not used, excrement may accumulate around the bends and curvature of the gooseneck structure an/or on the surfaces of the collection box during long term use, leading to an unsanitary and/or foul smelling environment in the squat room and the dwelling; and (3) the water seal may be ineffective if insufficient water is left in the gooseneck, allowing for passage of gases and insects. 
         [0013]    In another version of the offset pit latrine, the blockage of sewer gases and/or insects is attempted by interposing an S-trap or a U-bend in the pipe located between the squat pan and the leach pit, to facilitate formation of water seal. These bends frequently and regularly become blocked by the bulky anal cleansing materials (cardboard, grasses, leaves, maize cobs, vegetable peels, cement bags, rags, etc.) utilized in the absence of Western-style toilet paper, resulting in sewage backup or a reversion to non-sanitized waste disposal methods. They also require a larger volume of water to completely flush excreta to the pit. Moreover, many times there remains insufficient water in the pipe to form a seal, defeating altogether the purpose of installing a U-bend or an S-trap in the first place. Furthermore, when U-bends or other conventional water traps have sufficiently large cross sections to avoid clogging (e.g., 3 inches or larger in diameter), they may require large quantities of water to flush, as the trapway or U-bend itself may hold more than a liter of water to form a complete seal. This is disadvantageous as it requires the user to often carry and store larger amounts of water to the latrine, often over long distances. It can result in a more rapid filling of the pit when drainage or filtering of liquid from the pit is hampered by dense soil. 
         [0014]    Thus, there remains a need in the art for a system including a latrine pan and a collection device that can be inexpensively produced and distributed, that reduces the potential for pathogen transmission through flying insects, reduce or prevent backflow of sewage gases, requires minimal water for flushing, is easy to maintain and use and which is suitable for installation in an offset pit latrine having one or more offset leach pits. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    The invention described herein includes a latrine pan and collector system for use in an offset pit latrine. The system permits use of a latrine pan having a flapper in an offset leach pit context, and eliminates the necessity of large scale installation of a concrete collection box, which can collect unsanitary debris. The system of the invention includes (1) a pour-flush latrine pan and (2) a collector. The pour-flush latrine pan is mountable at a surface comprising a collection basin and a flapper, the collection basin having an upper bowl portion tapering to an outlet extending through a wall of the collection basin at a lower end of the collection basin, the flapper comprising a counterbalance device and a coverplate disposed on opposite sides of a pivot. The coverplate has a shape adapted to cover the outlet of the collection basin when the coverplate is engaged against the lower end of the collection basin. The flapper is pivotally mounted against the collection basin such that the coverplate engages against the lower end of the collection basin when a pivotal force attributable to the counterbalance device is greater than a pivotal force applied to the coverplate that engages the lower end of the collection basin. The collector includes a collector body that engages the latrine pan, defines a discharge opening, and secures an inclined surface sloping downwardly between an impact zone positioned beneath the outlet of the latrine pan and the discharge opening, the collector body securing the inclined surface at a position sufficiently distant from the underside of the latrine pan so that the inclined surface does not impede pivoting of the flapper, whereby material discharged from the outlet of the latrine pan contacts the inclined surface at the impact zone and slides downwardly from the impact zone to the discharge opening. 
         [0016]    Also included is the collector described above, related latrine structures and methods. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0017]    The foregoing summary, as well as the following detailed description of embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which may be preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
           [0018]      FIG. 1  is a schematic representation of a prior art offset leach pit, shown in cross section; 
           [0019]      FIG. 2  shows a schematic plan view of an offset prior art latrine shelter and squat pan connected to two offset leach pits; 
           [0020]      FIG. 3  is a cross sectional view of a prior art squat pan having a “gooseneck” bend at its outlet; 
           [0021]      FIG. 4A  is a perspective view of the pour-flush latrine pan of the invention alone in the “closed” position; 
           [0022]      FIG. 4B  is a perspective view of the pour-flush latrine pan of the invention alone in the “open” position; 
           [0023]      FIG. 5A  is a front view of latrine pan of the system of the invention of  FIGS. 4A and 7B , where the latrine pan is illustrated in the “closed” position; 
           [0024]      FIG. 5B  is a front view of latrine pan of the system of the invention of  FIGS. 4A and 7B , where the latrine pan is illustrated in the “open” position; 
           [0025]      FIG. 6A  is a back view of the pour-flush latrine of the invention of  FIGS. 4A  and B, where the latrine pan is illustrated in the “closed” position; 
           [0026]      FIG. 6B  is a back view of the pour-flush latrine pan of  FIGS. 4A and 4B , where the latrine pan is illustrated in the “open” position; 
           [0027]      FIG. 7A  is a first perspective view of a first embodiment of the collector of the invention; 
           [0028]      FIG. 7B  is a second perspective view of a first embodiment of the collector of the invention; 
           [0029]      FIG. 8  is a side view of the collector of  FIGS. 7A and 7B ; 
           [0030]      FIG. 9A  is a front view, respectively, of the collector of the system of the invention of  FIGS. 7A and 7B ; 
           [0031]      FIG. 9B  is a back view, respectively, of the collector of the system of the invention of  FIGS. 7A and 7B ; 
           [0032]      FIG. 10A  is a cross sectional side view of the collector with a latrine pan nested therein to form an embodiment of the system of the invention. The latrine pan is illustrated in the “closed” position; 
           [0033]      FIG. 10B  is a cross sectional side view of the collector with a latrine pan nested therein to form an embodiment of the system of the invention. The latrine pan is illustrated in the “open” position; 
           [0034]      FIGS. 11A ,  11 B,  11 C, and  11 D shows the system of  FIGS. 10A  and B in the serial steps of an open/close cycle of the flapper and delivery of the excreta towards the offset leach pit; 
           [0035]      FIG. 12  is a perspective view of an alternative embodiment of the collector of the invention which can be used with the latrine pans of, e.g.,  FIGS. 4A ,  4 B, or other pans having a pivoting flapper; 
           [0036]      FIG. 13  is a top plan view of the collector of  FIG. 12 ; 
           [0037]      FIG. 14  is a front view of the collector of  FIG. 12 ; 
           [0038]      FIG. 15  is a side view of the collector of  FIG. 12 ; 
           [0039]      FIG. 16  is a back view of the collector of  FIG. 12 ; 
           [0040]      FIG. 17  is a bottom plan view of the collector of  FIG. 12 ; 
           [0041]      FIG. 18  is a perspective view of the collector of  FIG. 12  engaged with the latrine pan of  FIGS. 4A  and B to form an embodiment of a collector system of the invention; 
           [0042]      FIG. 19  is a top plan view of the collector system of  FIG. 18 ; 
           [0043]      FIG. 20  is a front view of the collector system of  FIG. 18 ; 
           [0044]      FIG. 21  is a side view of the collector system of  FIG. 18 ; 
           [0045]      FIG. 22  is a back view of the collector system of  FIG. 18 ; 
           [0046]      FIG. 23  is a bottom plan view of the collector system of  FIG. 18 ; 
           [0047]      FIG. 24  is a perspective, cut-away view of the collector system of  FIG. 18 , wherein the cuts are taken along the planes identified in  FIG. 18 ; 
           [0048]      FIG. 25  is a cross sectional side view of the collector system of  FIG. 18 ; wherein the flapper of the latrine pan is in the open position; 
           [0049]      FIG. 26  is a cross sectional side view of the collector system of  FIG. 18 ; wherein the flapper of the latrine pan is in the closed position; 
           [0050]      FIG. 27  is an alternative perspective, cut-away view of the collector system of  FIG. 20 , wherein the cuts are taken along the planes identified in  FIG. 18 ; 
           [0051]      FIG. 28  is a cut away front view of the collector system of  FIG. 18 , wherein the cuts have been taken along the planes shown in  FIG. 23 ; 
           [0052]      FIG. 29  is a side view of a third embodiment of the collector, wherein the collector is designed to be self-stacking; 
           [0053]      FIG. 30  is a cross section side view of the collector for  FIG. 29 ; 
           [0054]      FIG. 31  is the collector of  FIG. 29  illustrating connection of the collector&#39;s discharge outlet to a pipe to convey waste to an offset leach pit; 
           [0055]      FIG. 32A  is a top plan view of an embodiment of the system of the invention installed in a cement slab of an offset pit latrine; 
           [0056]      FIG. 32B  illustrates a cross section of the latrine pan engaged with the collector and slab installment taken at X-X 1  of  FIG. 32A  in an embodiment of the system of the invention; and 
           [0057]      FIG. 33  is a schematic of representation of a pour-flush latrine and an embodiment of the collector system of the invention shown in cross section, wherein the latrine pan is remotely located from the offset leach pit, and the discharge outlet of the collector is in fluid communication with the leach pit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0058]    The invention described herein includes a system for use in an offset pour-flush latrine that comprises a latrine pan and a collector system. The system is advantageous as it can be inexpensively mass produced; it is lightweight but durable, so can be transported to remote areas at relatively low cost. The system is resistant to blockage under everyday use when installed as part of an offset pit latrine, prevents flying insects from passing in and out of the pit, and prevents or reduces the backflow of sewage gases from an offset leach pit into the squatting room or residence in which the pour-flush latrine pan is sited. 
         [0059]    Also contemplated within the scope of the invention are offset pour-flush latrines, methods of reducing the incidence of adverse health effects, methods of preventing or ameliorating the flow of sewage gases, such as hydrogen sulfide or ammonia, from an offset leach pit, methods of installing the pour flush latrine pan into an offset pit latrine, and methods of sustainably and hygienically removing human excreta from human contact. Each aspect of the invention is described in detail below. 
         [0060]    The invention in some embodiments will be described with reference to the drawings provided herein. In the specification, words such as “inner” and “outer,” “upper” and “lower,” “superior” and “inferior,” “distal” and “proximal”, “inwardly” and “outwardly,” and “uppermost” and “lowermost,” and words of similar import are used for assisting in the understanding of the invention when referring to the drawings and absent a specific definition or meaning otherwise given by the specification for such terms, should not be considered limiting to the scope of the invention. 
         [0061]    The system of the invention includes a latrine pan and a collector for directing towards an offset leach pit a material discharged from the latrine pan. The latrine pan which is a part of the inventive system is described and illustrated in detail in co-pending U.S. application Ser. No. 13/770,923, of AS IP Holdco, LLC entitled “Pour-Flush Latrines, Latrine Pans, Latrine Pan Assemblies, and Related Methods,” the contents of which are incorporated herein by reference. Any latrine pan or related device or structure described therein can be used in the system as described herein. However, for purposes of narrative coherence, some broader aspects of the latrine pans are described herein relative to the collector and other system components. 
         [0062]    The latrine pan of the system is mountable at a surface and includes a pour-flush latrine pan that includes a collection basin and a flapper. The collection basin may be of any size, design or shape known or to be developed in the art. For example, the collection basin design may be circular, oval, square, kidney-shaped or triangular when regarded in plan view. As will be understood in the art, numerous “squat pan” designs have been developed based upon cultural and habitual preferences and any of these designs may be employed in the present invention. Regardless of the specific shape, it may be preferred that the design/shape of the collection basin be adapted to reducing urine splashing, facilitate flushing of excreta and sanitary products with minimal water flow, permit assumption of a comfortable collection position by adults, and/or be on a scale that can be safely used by children. 
         [0063]    In an embodiment, the collection basin is formed as a squat pan and includes a bowl having a radially extending elongated portion, such that the collection basin&#39;s top plan view resembles a stylized pear-shape (see, e.g.,  FIG. 3A ). In this embodiment, it may be preferred that the elongated portion extends from the upper bowl portion only, so that the collection basin has a non-uniform depth, with the bowl of the basin through which the outlet extends, being the deeper. 
         [0064]    Regardless of the shape or size selected, the collection basin includes a bowl, an upper portion of which having walls that taper downwardly to an outlet. The outlet extends through a wall of the basin, preferably a wall in the lower end of the basin. The slope of the taper may be steep or gradual, depending on the design and shape of the overall collection basin. Preferably, the slope is adjusted to minimize splashing from the sidewalls and to facilitate progress of excreta and other waste through the outlet. 
         [0065]    The outlet may be, for example, a simple hole defined by the lowermost sidewall of the basin or a conduit defined by the narrowing of the basin sidewalls of the lower end of the basin. In some embodiments, the outlet is defined by a structure that is adapted to be fitted to pipe or conduit, so that the latrine pan and the leach pit may be sited apart but remain in fluid communication. In an embodiment, the outlet has a diameter of about 10 cm to about 20 cm, although outlets of any dimension may be used. However, the most suitable dimension is one large enough to permit egress of the non-standard toilet paper substitutes used in the region where the latrine is to be installed but not so large that it poses a danger to small children. 
         [0066]    The pour-flush latrine pan of the invention also includes a flapper. The flapper itself includes a counterbalance device and a coverplate that are disposed on opposite sides of a pivot relative to one another. As noted with the collection basin, the flapper can be manufactured as one piece or as several pieces that are subsequently assembled together. The flapper or its component parts may be made of any of the materials discussed above as suitable for the collection basin, including coatings and additional surface treatments. 
         [0067]    The coverplate is adapted to cover the outlet of the collection basin when the coverplate is engaged against the lower end of the collection basin. If the outlet has a substantially circular cross section, it may be preferred that the coverplate is disc shaped, or modified-disc shaped (that is, discs with radial extensions, flanges, lips, etc.) and is of a diameter that is at least slightly greater than the diameter of the outlet, so that when the coverplate is engaged against the lower end of the collection basin the outlet is fully covered. 
         [0068]    To provide a liquid seal that prevents, reduces or ameliorates the passage of sewage gases and flying insects from one side of the cover plate (e.g., the side in communication with the leach pit) to the other side (e.g., the side in communication with the environment of the squatting room), it may be preferred that the coverplate has a shape that engages and folds upwardly around a lower end of the collection basin, thereby forming a receptacle or channel for collecting a portion of flush water. The flush water that remains on the cover plate after closure of the flapper creates an airtight liquid seal between the collection basin and the coverplate of the flapper. 
         [0069]    The reliability of the seal can be improved by ensuring that any remaining flush water is directed towards the interface of the outlet of the collection basin and the flapper. Thus, it is preferred to form a channel around the perimeter of the coverplate. The channel may engage the entire perimeter of the lower end, or only a portion of the perimeter of the lower end. 
         [0070]    Additionally, in an embodiment, the coverplate may contain a convex portion that extends within the outlet of the collection basin when the coverplate is engaged against the lower end of the collection basin. The convex portion aids in the reduction of upward splashing of water during use. The convex portion also facilities proper alignment/re-alignment of the channel and the lower end of the basin after an open/close cycle of the flapper. In some embodiment, the rise of the convex portion may serve as a wall of the channel. 
         [0071]    Under everyday use of the pour-flush latrine pan, several milliliters of flush liquid will remain residing in the channel after flushing, forming a liquid seal between the surface of the coverplate and the lower end of the basin. The seal serves to prevent, reduce and/or ameliorate the backflow of gases from the leach pit into the environment of the residence or squatting room. Such reduction may be at least by 50%, by 80% or by 90% or more as compared to an uncovered leach pit. Advantageously, the seal may also prevent entry of most types of insects into the human environment or into the leach pit, blocking a major transmission route for diarrheal diseases. 
         [0072]    In an embodiment of the invention, the channel is designed to capture and retain a minimal amount of liquid—enough to create a functional seal, but not enough to give rise to excessive splashing during use, and not enough to require use of an extremely large counterweight which would place unnecessary stress on the hinge of the flapper. 
         [0073]    When using the latrine pan, the flapper is pivotally mounted against the collection basin. The coverplate and a counterbalance device are disposed on opposite sides of the pivot. The coverplate is placed so that it covers the outlet, as described above, and on the other side of the pivot is located the counterbalance device. The flapper “teeter totters” between a closed state (where the coverplate is engaged against the lower end of the basin) and an open state (where the coverplate and the lower end disengaged and spaced apart to permit egress of excreta and other waste into the leach pit). Whether the flapper is in an “open” or a “closed” state depends on which end of the flapper is exerting the greater pivotal force. 
         [0074]    Specifically, the counterbalance device serves to maintain the closed state of the flapper by exerting a pivotal force that is greater than any counter pivotal force applied to the coverplate either: (1) when the coverplate is vacant (and/or contains water for the water seal) or (2) when the coverplate bears excreta or other waste. The counterbalance device must have a mass that exerts a pivotal force that is greater than or equal to the pivotal force exerted by an average excreta quantity, but not greater than the force exerted by a hand poured water stream. As will be appreciated in the art, such mass will vary depending on the location of the pivot relative to the counterbalance device, but any such adjustments are well within the purview of a person of ordinary skill in the art and/or common sense. 
         [0075]    In an embodiment, the pivot is substantially equidistant between the coverplate and the counterbalance device, and the center of mass of the counterbalance device or the coverplate is about 5 to about 20 centimeters from the pivot. 
         [0076]    In a simple iteration, the counterbalance device may be any material of sufficient mass or weight (“weight material”) secured to the flapper, either during manufacture or post-manufacture. For example, the counterbalance device may be a rock, brick or block of suitable sized or mass found on site as the latrine is constructed that is affixed to the flapper. 
         [0077]    As noted above, the amount of weight material will vary depending on the amount of pivotal force that the counterbalance device must exert. The volumetric dimensions of the container will necessarily vary depending on the amount or type of weight material that is required in a specific latrine application. It may be preferred that the container has volumetric dimensions (that is, be of a size) to contain an amount of weight material sufficient to exert a pivotal force upon the flapper that is greater than a pivotal force exerted on the flapper by an average excreta quantity when the average excreta quantity rests and/or makes impact with the coverplate when delivered by gravity from a point about 40 to about 70 centimeters from the surface of the coverplate. By “average excreta quantity” it is meant about one average bowel movement from a reasonably healthy individual suffering from no significant gastrointestinal disorders. 
         [0078]    The flapper is pivotally mounted against the collection basin so that the coverplate engages against the lower end of the basin. The flapper may be pivotally mounted directly to the basin (for example, to its exterior), or it may be mounted on a nearby structure (such as a wall, a post or the collector). The pivot may take the form of any known or to be developed in the art. For example, without limitation, the pivot may be an arrangement of aligned holes in the flapper and the basin and pins; the flapper may include a loop through which a baton is inserted, allowing for pivotal rotation; the pivot may be a flexible bracket on the underside of the basin through which the flapper is threaded, or the pivot may be a fulcrum inserted beneath the flapper. 
         [0079]    The system also includes a collector. The collector is designed to be engaged with the latrine pan so as to substantially enclose at least the underside portion of the lower end of the collection basin, where the outlet of the collection basin is located and to facilitate the transfer (via a combination of gravitational force and the force of the flush water) of the waste material from the outlet of the collection basin of the latrine pan to the discharge opening of the collector and towards the offset leach pit. 
         [0080]    The collector may be manufactured as an integral piece or it may be manufactured in components (of the same or of different materials) that are subsequently assembled. The collector and/or any of its components may be independently cast, molded, thermoformed, stamped, carved or otherwise formed, depending on the material selected. Any material known or to be developed in the art may be used, such as, without limitation, a polymer, a plastic, a composite, a metal, a concrete, a cement, a natural or synthetic stone, a composite, a wood, a fiberglass, a marble, a porcelain, a ceramic, gravel, and a clay. It is preferred that the material selected is durable, resistant to crazing, and smooth surfaced. 
         [0081]    The collector may be formed of a first material, and then coated with one or more of a second material to realize desirable surface properties. For example, the collection basin may be made of a fiberglass material that is coated with a non-stick polymer (for example polytetrafluoroethylene (TEFLON®)) to increase the ability to maintain a clean, excreta-free surface or an antibacterial coating, such as nanoparticles of titanium dioxide, silver, copper, gold, and/or gallium. 
         [0082]    In some embodiments, the material of the collector and/or its component parts is a thermoplastic or thermoset polymer or copolymer as such materials are durable, relatively inexpensive and easy to fabricate and to clean. Suitable plastics may include polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene, polyvinylidene chloride, high impact polystyrene, polyamides, acrylonitrile butadiene styrene, polyethylene/acrylonitrile butadiene styrene, polycarbonate, polycarbonate/acrylonitrile butadiene styrene, polyurethanes, melamine formaldehyde, phenolics, polyetheretherketone, polyetherimide, polymethyl methacrylate, polytetrafluoroethylene, and/or urea-formaldehyde. In some embodiments, one may utilize thermoplastic or thermoset polymer or copolymer materials that have been compounded with antimicrobial additives such as triclosan, zinc pyrithione, silver-containing compounds, or other suitable antimicrobial additives known in the art. 
         [0083]    A first, non-limiting embodiment of the collector and/or the system with the latrine pan included in the invention is illustrated in  FIGS. 4 to 11 . With reference to these Figures, a pour-flush latrine pan  100  that includes a collection basin  102  and a flapper  104  is shown. The collection basin  102  includes an upper bowl portion  108  having an upper edge  154 , which includes a flange  140  that encircles the perimeter of the upper edge  154 . Upon installation of the pour-flush latrine pan  100  into a cement apron or slab  170 , the flange  140  is substantially co-planar with the surface  160  of the slab  170 . In an embodiment, the flange may be, for example, mounted at some distance below the surface of the concrete slab, and the concrete slab is tapered or chamfered to meet the collection or bowl portion of the latrine pan to avoid chipping of the concrete at the otherwise sharp corner. 
         [0084]    In these illustrative Figures, the flange  140  is shown as extending around the entire perimeter of the collection basin; in practice the flange may extend for only a portion or several discontinuous portions of the perimeter or be wholly absent. 
         [0085]    The bowl  107  of the collection basin  102  includes an upper bowl portion  108  that includes an interior wall  120  that tapers downwardly to an outlet  112  that extends through the basin&#39;s wall at a lower end  116  of the collection basin  102 . 
         [0086]    The pour-flush latrine pan  100  further includes a flapper  104  that in turn includes a coverplate  106  and a counterbalance device  118  that are disposed on opposite sides of a pivot  122 . In the embodiment shown in the Figures, the flapper  104  is pivotally mounted to the exterior  152  of the collection basin  102 . The pivot  122  is an aligned holes-and-pin configuration; a first set of holes  147 ,  147 ′ (not shown) extends through an extension body  146  of the flapper  104 , and a second set of holes  148 ,  148 ′ (not shown) are present in a spaced bracket  150 ,  150 ′ on the exterior  152  of the collection basin  102 . 
         [0087]    In the closed state, the flapper  104  causes the coverplate  106  to engage against the lower end  116  of the collection basin  102  covering the outlet  112 . The outlet  112  has a circular cross section; thus the coverplate  106  is substantially disk shaped so as to be adapted to cover the outlet  112  when the coverplate  106  is engaged against the lower end  116  of the collection basin  102 . The coverplate  106  includes a centered convex portion  136 , a circumferential rim  138 , and a lip  168 . The circumferential rim  138  extends above the lower end  116  of the collection basin  102  basin when the flapper  104  is in the closed position and serves to hold a portion of flush water within the coverplate and create an airtight seal. 
         [0088]    A channel  124  is also included in the coverplate  106 . During use, the channel  124  assures that a quantity of the residual pour-flush liquid is directed to the perimeter of the coverplate to form a liquid seal  128  between the coverplate  106  and the lower end  116  of the collection basin  102 . 
         [0089]    The flapper  104  also includes a counterbalance device  118  that is illustrated as a hollow cup or cylinder  162 . It can be filled with a weight material  161  that is cement as the latrine pan is prepared for site installation. 
         [0090]    The collector  200  includes a collector body  202  that engages the latrine pan  100 . In an embodiment that may be preferred, the collector body  202  is nested with the latrine pan  100 , such that at least a portion  220  of the collector body  202  is in conformation with the collection basin  102  of the latrine pan  100 . In the illustrative embodiment shown in  FIGS. 4 to 13 , the collector body  202  is entirely nested with the latrine pan  100 , such that substantially all the sidewalls of the collector body  202  are in conformation with those of the collection basin  102  of the latrine pan  100 . 
         [0091]    A discharge opening  204  is defined by the walls of the collector body  202 . The discharge opening may be any shape or size; the shape or size will necessarily depend on the cross sectional shape of the pipe or other conduit to which the discharge opening is to be connected. For example, in some regions of the world PVC pipe having a cross sectional diameter of 3 inches or of 4 inches is readily available and is commonly used in latrine construction. Thus, in embodiments destined for use in that geography, it may be desirable that the discharge opening is circular with an approximately 3 inch or 4 inch diameter. In general, it may be desirable that the x dimension of the discharge opening is in a range of about 1 to about 10 inches and the y dimension is independently about 1 to about 10 inches. 
         [0092]    The discharge opening  204  may be located in a bottom portion  203 , a back side portion  234 , or a front side portion  232  of the collector body  202 . In addition, it may be preferred that the location of the discharge opening  204  is offset relative to a hypothetical central vertical axis passing through the collector. The location will vary depending on the relative location of the pipe or leach pit to which the collector body is to be placed in fluid communication. For example, with reference to, e.g.,  FIG. 7A  or  9 B, the discharge opening  204  may be formed in the back side portion  234  of the collector body  202 . 
         [0093]    In some embodiments, the collector body (any embodiment)  202  may include a flange  214  that is disposed around at least portion of the periphery of an upper end  218  of the collector body  202 . Alternatively, the flange  214  may be disposed around the entirety of the periphery of an upper edge  218  of the collector body  202 . 
         [0094]    In practice of the system, the collector body  202  is engaged with the latrine pan and it secures an inclined surface  206  that slopes downwardly towards the discharge opening  204  at a position beneath the latrine pan. By “secure(s)” it is meant that the collector body maintains the inclined surface at a position but that the inclined surface itself may be a separate or non-unitary from the collector body (such as, for example, an insert into the collector body or a component part suspended from the collector body) or it may be formed into and therefore be part of the collector body. 
         [0095]    It may be preferred that the inclined surface  206  is secured so as to be positioned at least beginning at an impact zone  208  of the collector body  202 . The impact zone is the area of the collector body where waste material, either solid or liquid, comes in contact with the interior surface  210  of the collector body  202  as it is released from the coverplate  102 . In most embodiments, the impact zone is an area beneath the outlet  112  of the latrine pan  100 . It may be preferred that the inclined surface  206  may extend from the impact zone  208  downwardly and terminate at the outer edge  212  of the collector body  202  that defines the discharge opening  204 . However, in alternative embodiments, it may be preferred that the inclined surface begins in front of the impact zone and/or terminates prior to the discharge opening. 
         [0096]    The topography of the inclined surface  206  may be any known or developed in the art and may be modified to facilitate the travel of liquid and or solid waste from the impact zone to the discharge opening. For example, the topography of the inclined surface may be substantially planar, rounded or contain channels or grooves. 
         [0097]      FIGS. 4-11 , discussed above, provide a non-limiting example of the system where the collector body and the latrine pan are nested together and the upper edges of each are substantially in conformation with one another. When a latrine is constructed using this embodiment, the latrine pan and the collector are nested together and together cast into a cement slab. 
         [0098]    Other embodiments of the collector and/or system of the invention are contemplated; for example,  FIGS. 12-28  illustrate an alternative exemplary embodiment of the invention where the discharge opening  204  of the collector is located at a back side portion  234  of the collector body  202 , and the collector body  202  is partially nested with the latrine pan  100  such that at only a portion  220  of the collector body  202  is in conformation with the collection basin  102  of the latrine pan  100 . 
         [0099]    Referencing  FIG. 12-17 , a alternative embodiment of a collector  200  is shown having a collector body  202  that secures an inclined surface  206  that descends towards a discharge opening  204  that is sited in a back side  232  of the collector body. The upper portion of the collector body  202  terminates in an upper edge  218  from which sidewalls of the collector body descend to a bottom portion  194  of the collector. In this particular embodiment, the upper edge  218  extends around the periphery of the collector body  202  defining a top opening  110  having a stylized cruciform shape (i.e., an extended oval with laterally bulging sides) when viewed in plan view. By virtue of the shape of the top opening  110  defined by the upper edge  218 , the descending sidewalls also bulge or extend laterally forming lateral protrusions  114 . 
         [0100]    From the upper edge  218  of the collector  200 , a flange  214  or lip extends laterally about the entire periphery of the upper edge  218 . As shown in the  FIGS. 12-17 , the flange  214  may contain one or more securement holes  132  spaced along flange  214 , which can be used to secure the collector  200  to a platform, slab or other latrine structure. Alternatively or additionally, other mechanism to secure the collector may be attached to the flange, including, for example, mechanical fasteners like rivets or clips. 
         [0101]    In the exemplary embodiment shown of the collector in  FIGS. 12-17 , a discharge opening  204  is defined by the walls of the collector body  202  and is located at a back side  232  of the collector body. The inclined surface  206  secured by the collector body  202  slopes downwardly terminating at the discharge opening  204 . 
         [0102]      FIGS. 18-29  illustrate the alternative embodiment of the collector described above coupled with the latrine pan having a pivoting flapper that was previously described and shown in  FIGS. 4-6  to form an alternative embodiment of the assembly of the invention. In this embodiment of the systems, the collection basin  104  of the latrine pan  100  is partially, but not wholly nested with the collector  200 . The exterior side portions of the bowl  107  of the latrine pan  100  are engaged with the protrusions  114  of the collector, see, e.g.,  FIG. 28 . Thus, the latrine pan  100  remains only partially nested within and/or is “offset” relative to the collector  200 , and the upper edge  154  of the collection basin remains elevated above the upper edge  218  of the collector body. See, e.g.,  FIG. 21  or  22 . This, combined with the placement of the discharge opening, permits pivoting of the flapper  104  and flow of waste from the coverplate  106  to the inclined surface  206  and ultimately the discharge opening  204  even when the collector  200  is relatively shallow. 
         [0103]    In the practice of this embodiment ( FIGS. 18-29 ), the latrine pan  100  is cast into a slab, and the collection box  200  is buried in the earth or foundation at the site of installation. Subsequently, the slab containing the latrine pan is laid over the collection box. The vertical distance that is shown in, for example,  FIG. 20 , between the bottom surface of the flange  154  and the upper edge  218  of the collection box is sized to correspond to the planned thickness of the slab into which the latrine pan is cast. The vertical distance that is shown in, for example,  FIG. 22 , between the bottom surface of the flange  154  and the upper edge  218  of the collection box is sized to correspond to the planned thickness of the slab into which the latrine pan in cast. 
         [0104]    In some embodiments of the any of the collectors and/or systems described herein, the collector may be adapted so that it can be nested with other, identical collectors (“self-stacking”). This ability to nest or stack permits conservation of space, particularly significant when the collectors are being conveyed in large numbers from a place of manufacture to a site of assembly, distribution or use. Additionally, collectors having geometries that are capable of nesting or stacking generally involve less complex (and therefore less expensive) molding processes. 
         [0105]    Without wishing to be limiting, such embodiments may include simply adapting the portion of the collector wall which define the discharge outlet so that the discharge outlet is inset relative to a back wall of the collector body. In these embodiments, to attach the collector to a pipe or conduit leading to an off set leach pit, one may use conventional adapters or joins, as described above. Alternatively, one may size the pipe to have a slightly smaller diameter or circumference measurement than that of the discharge outlet; the end of such pipe or conduit may then be inserted directly into the discharge outlet. In this configuration the end of the pipe extends at least partially into the portion of the collection cavity defined by the bottom portion of the collector body. 
         [0106]    Alternatively, with reference to  FIGS. 29-31 , the bottom portion  203  of the collector body  202  may include an interior shelf  246  that has a bottom surface  248  and a pair of extension members  258 A and  258 B, extending downwardly from the interior shelf  246  and having a geometry that conforms to the external contours of at least the upper portion of the pipe or conduit to be used in the installation. 
         [0107]    For example, if the pipe has a circular cross section, the extension members may be arctuate so that upon insertion of the pipe into the outlet, the extension members conform to the external surface of the pipe. It may be desirable that the extensions extend no further than the midline of the pipe or conduit. 
         [0108]    With reference to the Figures, when pipe  180  is inserted into the discharge outlet  204 , the pipe&#39;s bottom outer surface  252  mates with the collector&#39;s bottom portion  203  and the outer top surface  250  of the pipe  180  is mated with both the bottom surface  248  of shelf  246  and with the extension members  258 A and  258 B. The shelf  246  may be parallel to a hypothetical horizontal axis passing through the collector  200  or it may be tilted slightly downwardly to facilitate a secure pipe-discharge outlet connection. In some embodiments this angle is about equal to the angle of the bottom portion  203  relative to the horizontal and/or is may be about 10 to about 20 or about 15 degrees from horizontal. 
         [0109]    The endmost portion  240  of the body wall defining the discharge opening  204  terminates at an outlet end  240 . In this embodiment, it may be desirable, for manufacturing reasons, that an angle formed between the outlet end  240  and a hypothetical vertical axis is about 0.1 degrees to about 10 degrees. This variance facilities nesting and use of a simpler mold and molding process while still maintaining the security of the pipe-outlet connection upon assembly. 
         [0110]    Optionally, the embodiment may include a wedge  244  having a thin edge  254  and a thick edge  256 . The wedge is placed along the inclined surface  206  of the bottom portion  203  of the collector. The wedge is oriented so that the thick end  256  of the wedge  244  is spaced apart from the outlet edge  240 ; for example, the thick end  248  of the wedge may be about 0.5 to about 3 inches from the outlet end  240 , or about 1 inch from the outlet end  240 . The wedge  244  serves to provide a smooth flow path for waste at the interface of the collector and the pipe. Accordingly, it may be desirable that the thin edge of the wedge is as thin as possible and the thick end of the wedge has a transverse thickness that is substantially equal to the thickness of the pipe wall. 
         [0111]    These and other versions of self-stacking collectors are contemplated with in the scope of the invention and may be used in combination with a latrine pan having a pivoting flapper to create any of the systems or assemblies described herein. 
         [0112]    In some embodiments, it may be desirable to fabricate or to coat at least the inclined surface of the collector out of or with a material that provides a smooth, friction reducing surface to better facilitate passage of solid waster materials to the discharge outlet. In addition or alternatively, the material of the inclined surface may be antibacterial or microbe resistant and include as examples the specific materials given above. 
         [0113]    When the system is assembled (referencing all of the embodiments), the collector body  202  secures the inclined surface  206  at a position relative to the latrine pan  100  such that the inclined surface  206  does not impede the pivotable flapper  104  upon flushing (pivoting). As will be recognized by a person of skill in the art, the position of the inclined surface  206  will necessarily vary, depending on the scale and dimensions of the latrine pan and the system as a whole. In some embodiments, it may be preferred however, that the vertical distance D between the pivot and the inclined surface (as show in, for example  FIG. 7 ) may be about 5 inches, about 10 inches, about 20 inches, about 30 inches and about 40 inches. 
         [0114]    The angle of incline (slope) of the inclined surface  206  will also vary, depending on the precise scale and configuration of the collection system. It may be preferred that an angle a i  formed between the inclined surface and a hypothetical vertical axis y through the center of the outlet is about 65 to about 90 degrees, or about 70 to about 80 degrees. It may be preferred that the angle a i  formed between the inclined surface and a hypothetical vertical axis y through the center of the outlet is about 75 degrees, about 75.5 degrees, about 80 degrees, about 80.5 degrees, about 81 degrees, about 81.5 degrees, about 82 degrees, about 82.5 degrees, about 83 degrees, about 83.5 degrees, about 84 degrees, about 84.5 degrees, about 85 degrees, about 85.5 degrees, about 86 degrees, about 86.5 degrees, about 87 degrees, about 87.5 degrees, about 88 degrees, about 88.5 degrees, about 89 degrees, about 89.5 degrees, or about 90 degrees, about 90.5 degrees. 
         [0115]    In some embodiments, when the system is assembled, the collector body flange  214  may be situated beneath but adjacent to the flange  140  of the latrine pan  100 . The collector body  202  and the latrine pan  100  define a collection cavity  216  when the two are engaged. In some embodiments, it may be preferred that the collection cavity  216  communicates with the exterior of the cavity substantially via only the outlet  112  of the latrine pan and the discharge opening  204  of the collector body  202 . In alternative embodiments, however, the collection cavity  220  may be in communication with the exterior via other outlets or voids in the walls of the collector body. 
         [0116]    An offset pit latrine of the invention employing the system as describe herein can be sited in a public structure, such a marketplace public facility, a family residence or may be situated outside a family residence is a separate superstructure (a so-called “outhouse”). Preferred dimensions of the room or structure are about 800 mm by about 1000 mm or greater. The offset pit latrine may be configured by locating the latrine pan and collector system in a concrete slab within a dwelling or other structure, and the one or more leach pits sited at a distance from the system. 
         [0117]    The structure and design of leach pits are well established in the art and will vary depending topographical, cultural, and environmental conditions. Such adjustments are well within the skill set of a person of ordinary skill in the art and will not be repeated herein. 
         [0118]    With reference specifically to  FIG. 32A ,  32 B or  33 , a schematic of a sheltered, offset pit latrine  188  of the invention in cross section is illustrated, wherein the latrine pan system of  FIGS. 4-11  is utilized, although any embodiment could be included. The system  222  of the invention, including the pour-flush latrine pan  100  and the collector  200  is situated in a cement slab  170  and enclosed in a latrine shelter  176 . The pour-flush latrine pan  100  and the collector  200  are engaged such that the outlet (not visible) of the latrine pan  100  is in direct communication with the collection cavity  216  of the collector body  202 . Earth, concrete or other supporting material  224  may surround the exterior surfaces  226  of the collector  200 . 
         [0119]    The collector body  202  includes an adapter  228  that is disposed around the discharge opening of the collector body  202 . The adapter  228  engages a pipe  180  with the collector body  202 , thereby placing collector body  202  in direct fluid communication with the pipe  180 , and in indirectly fluid communication with the leach pit  126 . In other embodiments, the fluid communication of the collector body  202  and the leach pit  126  can be accomplished via other structural arrangements. For example, the collector body  202  may be configured to extend directly into the leach pit  126  or the pipe  180  and the collector body  202  may be joined or spliced together using adhesive, plumber tape, or in situ curing of an epoxy. As an alternative, a portion of the collector body  202  may be adapted to connect directly with the pipe  180 . 
         [0120]    During use of the system  222  in the offset pit latrine  188 , the latrine structure  176  is sited at a distance from the leach pit  126  but the system  222  remains in fluid connection with the leach pit  126 . The latrine structure  176 ′ houses the system  222 , with only the latrine pan  100  being visible from the perspective of the latrine user. The collector  200  is engaged with the latrine pan  100  and is sited beneath the latrine pan  100 . 
         [0121]    Depending on the size of the footprint available, the system can be placed about 1 to about 5 meters from the leach pit and connected to the leach pit via pipeworks and/or a junction or diverter box laid to a correct grade (preferably greater than about 1 in 30). The leach pit is preferably sealed with, preferably, the exception of at least one vent, which is sited preferably as far from the latrine pan as is feasible. The junction or diverter box can be formed of any suitable material, including or not limited to concrete, brick, plastic, metal, clay, glass, etc. 
         [0122]    In any offset pit latrine configuration an optional latrine pan cover may be provided to cover the latrine pan when not in use. 
         [0123]    Preferably, the system or the collector alone is fitted into a cavity that is substantially the same size and shape as the outer dimensions of the collector, so that the basin (with the exception of the outlet which should remain unobstructed) may be structurally reinforced. Such reinforcement extends may serve to extend the structural life of the system and prevent accidental falls into the leach pit in the event that an individual loses balance and makes bodily contact with the latrine pan or the collector. 
         [0124]    As an example, the cavity may be formed in the earth (when the outlet is connected via pipeworks to a remotely sited leach pit) or in a cement slab. A cement slab can be preferably cast around the collector or collector and latrine pan to ensure intimate contact between the surfaces and strong bonding of the collector to the slab. 
         [0125]    During the installation of the system and the building of the off set latrine, it is preferred that the system is cast into a cement slab of about 2 inches to about 6 inches (5.1 centimeters to 15.2 centimeters) in thickness. The slab should be reinforced with metallic wire to increase its strength and longevity. It is also possible to secure the latrine pan in a cavity formed in a cement slab which also serves to seal the leach pit, such that an upper edge of the collection basin and the upper edge of the collector is substantially flush with the surface of the slab. In other embodiments, the collector can be mounted substantially parallel to the place of the upper edge of the collection basin, but at some distance deeper into the concrete, i.e., not directly at the surface. This may help to ensure better retention of the collector and the latrine pan in the slab. The vertical distance between the collector and the latrine pan can be controlled with the use of spacers of a standard size. Alternatively, spacers can be molded into the upper surface of the collector or the lower surface of the collection basin flange  140 . It may be desirable in some circumstances to mold or otherwise permanently affix spacers into the outside walls of the collection basin. In yet another alternative, the collector may be installed as a separate part, i.e., not cast into the concrete slab. The latrine may be constructed so that the bottom surface of the concrete slab meets the upper flange of the collector when the slab is laid in place. 
         [0126]    In an embodiment of the latrine, the backmost edge of the system is located at least about 100 mm to about 150 mm from any wall or structure. Footbeds may be placed on either side of the latrine pan for user guidance, to ensure that the excreta is delivered as near as possible to the outlet. 
         [0127]    In a variation of the installation described above, the inventive system of the alternative embodiment shown in  FIGS. 18-29  is used. In such embodiment, the collection box is buried in the earth or foundation of the installation site. The latrine pan is independently cast into a slab, such as, for example, a concrete slab. The slab/pan structure is then placed over the buried collection box. The vertical distance that is shown in, for example,  FIG. 23 , between the bottom surface of the flange  154  and the upper edge  218  of the collection box is sized to correspond to the planned thickness of the slab into which the latrine pan in cast. 
         [0128]    Once installed, regardless of embodiment, the system can be easily operated and maintained. To use the latrine, the user squats over the collection basin of the latrine pan, first removing the latrine pan cover, if one was present. Since the latrine pan is initially empty except for the small amount of water that creates the water seal, the latrine pan is in the closed position. Preferably in the closed position, the user delivers the excreta, which is conveyed by gravity to the surface of the coverplate. The flapper remains in a closed position despite the added weight of the excreta on the coverplate. Ideally, a single purpose water dispensing vessel is maintained in an area near the latrine pan, and contains about 1 liter to about 3 liters of water. The water may be non-potable water, such as unpurified river water, sullage or grey water. 
         [0129]    Using the water dispensing vessel, the user then “pour-flushes” the latrine—he pours the water into the latrine pan; the force applied by the water increases the pivotal force exerted upon the coverplate, exceeding the pivotal force that is (counter) exerted by the counterbalance device, and cover plate is disengage from the lower edge of the outlet and is spaced apart from the outlet to permit egress of the excreta. Once the excreta have been removed from the coverplate, the flapper returns to closed position. In most instances, sufficient liquid residue should remain in the pan to create the liquid seal. In the event that additional liquid is necessary or the liquid acting as a seal evaporates under hot weather conditions, an additional aliquot of liquid can be applied to restore it. 
         [0130]    During the pour-flush process, the flapper  104  is toggled between the “closed” and the “open” position using balanced/unbalanced pivotal force. Referencing  FIGS. 11A ,  11 B,  11 C, and  11 D, which shows a cross section of the latrine pan, the pivotal force F 1  exerted by the counterbalance device  118  exceeds both the pivotal force F 2  exerted by the empty coverplate  106   a  and the pivotal force F 3  attributable to a coverplate  106   a  upon which rests an average excreta quantity  166 . The flapper  104  remains therefore in the closed position. When a water stream  130  is applied to the coverplate  106 , the pivotal force F 4  attributable to the water stream (alone or combined with F 3 ) exceeds F 1  and the flapper transitions to the open state disengaging from the coverplate, allowing the average excreta quantity  166  to pass from the coverplate  106   a . Subsequently, the average excreta quantity  166  descends to the impact zone  208  of the collector body  202 , and continues to descend along the inclined surface  206  towards the discharge opening  204 , where it egresses, either into a pipe (not shown) or the leach pit (not shown). 
         [0131]    It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.