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CLAIM OF PRIORITY 
       [0001]    This application is a US utility application and claims priority to U.S. provisional patent application 61/624,130 filed on Apr. 13, 2012, the contents of which are fully incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to a water drainage system. More particularly, the current invention relates to a water drainage system that may be used with a waterproof membrane to center and secure a waste water pipe in place. 
       BACKGROUND OF THE INVENTION 
       [0003]    Water drainage systems are common in every household. It is desirable to have a drain system that is clean, easy to install and adjust, safe, and inexpensive. Examples in the art of water drainage systems are inflexible and hard to adjust. Most are designed for singular purposes while limiting the possible uses with design flaws that exclude certain installation locations and functions as well as having complicated designs with a multitude of parts and areas of potential failure. The current invention fulfills the needs over previous disclosures, providing improvements and convenience in regard to align the drain system with the floor, and how to ensure no residual wastewater accumulates. 
       DESCRIPTION OF THE RELATED ART 
       [0004]    U.S. Pat. No. 8,060,956 to DeGooyer presents a bondable waterproof fabric membrane shower pan system. This system combines the use of a prefabricated pitched subfloor with a waterproof fabric membrane also comprising of a coupling drain system which attaches to the wastewater pipe. The design has multiple connection points where mechanical connections must be made in order to create a waterproof connection where two level surfaces meet. Since the system starts with a large flange on the bottom for connecting to a shower floor subfloor, it eliminates the possibility of fitting the lower drain body into a surface such as a roof. This mandates that you must build your final surface up to the height necessary for proper drainage. 
         [0005]    U.S. Pat. No. 4,562,602 to Cuschera presents a wide floor water drainage system to fit with a small waste water pipe. This design depicts an adaptor for a waste water capturing method wherein a large conical shaped pipe is inserted into the surface to be drained and where in a smaller pipe section is inserted from above into the larger pipe section. The pipes are secured and sealed together with several rubber gaskets as well as two exterior nuts to be attached from the bottom. This design in theory tries to accomplish the same goals wherein a small section of pipe is inserted into a larger pipe section where the waste water pipe is captured and centered. Since the adaptor is secured with nuts from the bottom of the subfloor surface, access to the drain from the floor below is necessary and damage may be done to the ceiling. This design also fails to allow for the capturing of waterproof membranes which will greatly increase the efficiency of the seals as well as creating a secure moisture barrier. 
         [0006]    Various implements are known in the art, but fail to address the entire problem solved by the invention described herein. A preferred embodiment of this invention is illustrated in the accompanying drawings and will be described in more detail herein below. 
       SUMMARY OF THE INVENTION 
       [0007]    According to this invention, a water drainage system is disclosed for use with a waterproof membrane covering a substrate medium above the floor wherein a wastewater pipe is installed. The water drainage system mechanically secures the water proof membrane and at the same time centers and anchors the waste water pipe. The major component of the water drainage system of the current invention comprises a coupling mechanism including a lower drain body and a pipe-capturing member. The coupling mechanism traps a waterproof membrane covering the surfaces onto which wastewater may be disposed. Together with several additional structures, the coupling mechanism ensures that the waste water flows into the waste water pipe that is secured in place. 
         [0008]    In particular, the current invention includes a large lower drain body encircling a receiving hole, the lower drain body having a top surface which pitches radially inward and downward toward the center. The lower drain body has a lower drain flange on the top portion of the lower drain body, the lower drain flange extending downward from the top surface. Below the lower drain flange, the lower drain body has a cylindrical section which is dramatically thinner than the lower drain flange in terms of center-to-exterior thickness. The lower part of the cylindrical section is preferably threaded, defining a threaded section generally designed to be connected to an anchoring nut having a threaded interior. 
         [0009]    The water drainage system further comprises a pipe-capturing member, the pipe-capturing member having a tubular section with a significant interior-to-exterior thickness and a top flange positioned above the tubular section, the top flange being thin in top-to-bottom thickness and extending outwardly. The tubular section and the top flange encircle a pipe hole, which may be used to receive the insertion of a waste water pipe. The exterior surface of the tubular section decreases in diameter from top to bottom while the interior diameter of the tubular section increases from top to bottom. The diameter change of the interior surface allows the pipe-capturing member to firmly capture a waste water pipe and center the pipe. Similarly, the diameter change of the exterior surface allows the pipe-capturing member to be firmly inserted into the lower drain body. The bottom surface of the top flange of the pipe-capturing member is pitched as to be parallel with the upper surface of the lower drain body. Within this parallel space a waterproof membrane can be trapped or mechanically connected, additionally the same parallel space has pitched weeping channels through the body of the pipe-capturing member, allowing seepage to find its way to the waste water pipe. At the point where the membrane meets the exterior tubular section of the capturing member, a plurality of weeping holes are located around the tubular section under the top flange to allow water to pass through into the waste water pipe. The capturing member may also include threaded inserts in order to secure a drain trim. 
         [0010]    Aside from the pipe-capturing member and the lower drain body, other structures may be included in the water drainage system disclosed by the current invention. A drain trim holder may be placed above the pipe-capturing member, the drain trim holder being preferably adjustable in height to level the water drainage system with the finished floor. A drain trim cover may be adopted to cover the drain trim holder. In addition, an anchoring nut may be used to secure the lower drain body to the ground. 
         [0011]    The current invention may cover a number of embodiments having variable components. One key feature is that two structures may embrace and held flush against a waterproof membrane. A separate but important aspect of the current design is to allow modest but important positioning of the drain trim holder, thus making the placement of the water outlet adjustable. 
         [0012]    In general, the present invention succeeds in conferring the following, and others not mentioned, desirable and useful benefits and objectives. 
         [0013]    It is an object of the present invention to provide a water drainage system that is safe and easy to install. 
         [0014]    It is another object of the present invention to provide a water drainage system that secures a waste water pipe in place. 
         [0015]    It is another object of the present invention to provide a water drainage system that may be used in combination with a waterproof membrane covering the floor. 
         [0016]    Yet another object of the present invention is to provide a water drainage system that may be easily adjusted in terms of position. 
         [0017]    Still another object of the present invention is to provide a water drainage system that does not cause water accumulation. 
         [0018]    It is another object of the present invention to provide a water drainage system that is robust and durable. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a top perspective view of the water drainage system of the present invention fully assembled in a subfloor medium. 
           [0020]      FIG. 2  is an exploded view of the water drainage system of the present invention. 
           [0021]      FIG. 3  is an exploded sectional view of the water drainage system of the present invention. 
           [0022]      FIG. 4  is a sectional view of the water drainage system of the present invention when the water drainage system is fully assembled in a subfloor medium. 
           [0023]      FIGS. 5  A-H provide a full illustration of the pipe-capturing member, wherein 
           [0024]      FIG. 5A  is a top perspective view, 
           [0025]      FIG. 5B  is a top view, 
           [0026]      FIG. 5C  is a bottom view, 
           [0027]      FIG. 5D  is a front view, 
           [0028]      FIG. 5E  is a back view, 
           [0029]      FIG. 5F  is a first side view, 
           [0030]      FIG. 5G  is a second side view, 
           [0031]      FIG. 5H  is a sectional side view; 
           [0032]      FIG. 6  A-H provide a full illustration of the lower drain body, wherein 
           [0033]      FIG. 6A  is a top perspective view, 
           [0034]      FIG. 6B  is a top view, 
           [0035]      FIG. 6C  is a bottom view, 
           [0036]      FIG. 6D  is a front view, 
           [0037]      FIG. 6E  is a back view, 
           [0038]      FIG. 6F  is a first side view, 
           [0039]      FIG. 6G  is a second side view, 
           [0040]      FIG. 6H  is a sectional side view; 
           [0041]      FIG. 7  is an exploded sectional view of an alternative embodiment of the water drainage system of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    The preferred embodiments of the present invention will now be described with reference to the drawings. Identical elements in the various figures are identified, as far as possible, with the same reference numerals. Such embodiments are provided by way of explanation of the present invention, which is not intended to be limited thereto. In fact, those of ordinary skill in the art may appreciate upon reading the present specification and viewing the present drawings that various modifications and variations can be made thereto without deviating from the innovative concepts of the invention. 
         [0043]      FIG. 1  is a top perspective view of the water drainage system of the present invention fully assembled in a subfloor medium. Shown in  FIG. 1  is the substrate medium  12  into which the water drainage system is installed. The substrate medium  12  is shown in partially cut-away view for clarity purposes. Also shown in  FIG. 1  are a drain trim holder  40  and a drain plate  18 , the parts of a water drainage system of the current invention that is visible when it is assembled. The preferred embodiment of the current invention may generally be installed in substrate medium  12  at the location of a wastewater pipe. Also referring to  FIG. 1 , the substrate medium  12  is covered by waterproof membrane  19 , which is a novel design to overlay a surface onto which wastewater may be disposed. For example, the waterproof membrane may be used to cover the bathroom floor or bathtub.  FIG. 1  is the overview for water drainage system after installation is completed. The line between points A and B serves as an indicator for the sectional views of the water drainage system in  FIGS. 3 , and  4 . 
         [0044]      FIG. 2  is an exploded view of the water drainage system of the present invention.  FIG. 3  is an exploded sectional view of the water drainage system of the present invention, with the sectional line marked between points A and B in  FIG. 1 .  FIG. 4  is a sectional view of the water drainage system of the present invention when the water drainage system is fully assembled. As a group,  FIGS. 2 ,  3 , and  4  demonstrate how the entire water drainage system would assemble and show essentially the same elements, including a drain plate  18 , a drain trim holder  40 , a pipe-capturing member  15 , a waterproof membrane  19 , a lower drain body  14 , and an anchoring nut  32 , with specific emphasis on different details of these element. 
         [0045]    As shown in  FIG. 2  and  FIG. 3 , the water drainage system includes a lower drain body  14  encircling a receiving hole  36 . The lower drain body has a generally tubular, cylindrical section  21  wherein its lower part is threaded, defining a threaded section  33 . On top of the cylindrical section  21 , the lower drain body  14  has a lower drain flange  28  that expands annularly, and the lower drain flange  28  has a significantly larger diameter than the cylindrical section  21 . The lower drain body  14  also has a top surface  31  above the lower drain flange  28 , the top surface  31  pitching downward and inward radially towards the center of the receiving hole  36 , creating a sloped surface that may funnel water to flow through dedicated channels into a waste water pipe. Referring to  FIG. 4 , the top outer edge of the lower drain flange  28  should be substantially flush with the top surface of the subfloor medium  12  onto which a waterproof membrane  19  may be attached. 
         [0046]    As shown in  FIG. 2  and  FIG. 3 , the water drainage system includes a pipe-capturing member  15  encircling a pipe hole  35 , the pipe-capturing member  15  having a tubular section  22  and a top flange  20  positioned on the tubular section  22 . The top flange  20  has an upper surface  24  and a lower surface  27 . Referring to  FIG. 3 , the lower surface  27  of the top flange  20  on the pipe-capturing member  15  has an annular pitch that matches the pitch of the top surface  31  of the lower drain body  14 , allowing flush contact between the lower surface  27  of the top flange  20  and the top surface  31  of the lower drain body  14  when the tubular section  22  of the pipe-capturing member  15  is inserted into the receiving hole  36  of the lower drain body  14 , if no membrane is separating the two structures. 
         [0047]    One of the basic functions that may be served by the water drainage system is to provide draining for an area that is covered by a waterproof membrane  19 . As indicated above, the waterproof membrane  19  is a unique design for coverage of surfaces that may be susceptible to flow or accumulation of waste water. The pipe-capturing member  15  and the lower drain body  15  may serve as a coupling mechanism for the waterproof membrane  19 . As shown in  FIG. 2  and  FIG. 3 , the top flange  20  of the pipe-capturing member  15  has a pitched lower surface  27  that matches the pitched top surface  31  of the lower drain body  14 . The tubular section  22  of the pipe-capturing member  15  may be inserted through a hole  37  on the waterproof membrane  19 , and into the receiving hole  36  of the lower drain body  14 , wherein the hole  37  on the waterproof membrane  19  has a diameter similar to the exterior diameter of the tubular section  22 , thus trapping the waterproof membrane  19  underneath the top flange  20  and above the lower drain flange  28 . Since the lower surface  27  of the top flange  20  has matching pitch angles as the top surface  31  of the lower drain body  14 , the coupling of the pipe-capturing member  15  and the lower drain body  14  causes the trapped section  25  of the waterproof membrane  19  to pitch as shown in  FIG. 2-4 , allowing close contact between the components. 
         [0048]    Referring to  FIG. 3  and  FIG. 4 , the exterior surface of the tubular section  22  of the pipe-capturing member  15  is tapered and decreases in diameter from the top, defined as the part closer to the top flange  20 , to bottom, making the exterior of the tubular section  22  a frusto-conical shape. Conversely, the interior diameter of the tubular section, which corresponds to the diameter of the pipe hole  35 , increases from top to bottom, making the pipe hole  35  a frusto-conical shape. 
         [0049]    The tapering of the interior and exterior diameters of the tubular section  21  of the pipe-capturing member  15  is generally not very significant. The tapering angles for the interior and exterior diameters are between 0.1-5°, with the preferred tapering angle to be around 1°. Thus, due to the small tapering angle, the changes of the diameters are not dramatic. 
         [0050]    Since the exterior diameter of the tubular section  22  of the pipe-capturing member  15  is tapered and decreases from top to bottom, it has a maximum exterior diameter positioned just beneath the top flange  20 . The maximum exterior diameter is substantially equal to the diameter of the receiving hole, which is substantially uniform. Referring to  FIG. 3  and  FIG. 4 , the tubular section  22  of the pipe-capturing member  15  may be inserted into the receiving hole  36  of the lower drain body  14  from the top. Since the exterior diameter on the lower part of the tubular section  22  is smaller than the diameter of the receiving hole  36 , the insertion is made easier. Moreover, the tapered exterior surface of the tubular section  22  permits application of a chemical bonding adhesive between the tubular section  22  and the interior of the lower drain body  14  without causing squeezing away of the adhesive when the tubular section  22  is being inserted into the receiving hole  36 . 
         [0051]    Since the interior diameter of the tubular section  22  of the pipe-capturing member  15  is tapered and increases from top to bottom, it has a minimum interior diameter positioned just beneath the top flange  20 . The minimum exterior diameter is preferred to be substantially equal to the generally uniform outside diameter of a wastewater pipe, which is to be inserted into the pipe hole  35  from the bottom. The tapered interior surface of the tubular section  22  makes the insertion of a wastewater pipe easier. Moreover, the tapered interior surface of the tubular section  22  permits application of a chemical bonding adhesive without causing squeezing away of the adhesive when the wastewater pipe is inserted into the pipe hole  35  of the pipe-capturing member. 
         [0052]    As shown in  FIG. 3 , the top flange  22  of the pipe-capturing member has an upper interior edge  29 , the upper interior edge  29  is shaped as a chamfer that extends radially, forming a funnel shape. Such a design facilitates the flowing of wastewater into the wastewater pipe, which is inserted into the pipe hole  35  of the pipe-capturing member  15 . 
         [0053]    Referring to  FIGS. 2 ,  3  and  4 , the pipe-capturing member  15  has weeping holes  17  though the body of the pipe-capturing member  15 . Each of the weeping holes  17  has one opening just beneath the top flange  22 , with another opening on the chamfer of the interior edge  29 . The weeping holes  17  are positioned at an angle to facilitate draining into the pipe hole  35  and the wastewater pipe in the pipe hole  35 . As shown in  FIG. 4 , the diameter of the top flange  22  is preferably smaller than the diameter of the lower drain flange  28 , making the waterproof membrane  19  to taper at location  34 , which is also shown in  FIGS. 2 and 3 . The tapering of the waterproof membrane  19  at location  34  creates a pocket, which may facilitate the flowing of wastewater to the water drainage system. Most of the waste water may make its way above the pipe capturing member  15 , over the chamfer  29  and into the wastewater pipe. Even if there is any wastewater flowing under the top flange  20 , it will still escape through the weeping holes  17  and into the wastewater pipe. 
         [0054]    As shown in  FIGS. 2 ,  3  and  4 , the water drainage system may further comprises an anchoring nut  32 , which has a threaded interior that may be fastened to the threaded section  33  of cylindrical section  21  of the lower drain body  14 . Referring to  FIG. 4 , the anchoring nut  32  may be placed beneath the substrate medium  12 , creating further stabilization to the water drainage system, making it more difficult to dislocate the lower drain body  14 , the pipe-capturing member  15 , and other components of the water drainage system. However, it should be noted that the lower drain body  14  may be connected to the anchoring nut  32  with other approaches, such as but not limited to: co-molding and gluing. The anchoring nut  32  may also be entirely left out if the water drainage system is sufficiently secured. 
         [0055]    As shown in  FIGS. 2 ,  3  and  4 , the water drainage system may further include a drain trim holder  40 , which may be positioned on top of the pipe-capturing membrane  15 . The drain trim holder  40  may have different designs according to specific needs. In the embodiment shown in  FIGS. 2-4 , the exterior wall  41  of the drain trim holder  40  has a saw tooth design and the interior wall  43  of the drain trim holder  40  has a square tooth design. These designs allow the height of the drain trim holder  40  to be adjusted depending on the thickness of the material to be used on the finished floor, into which the water drainage system is installed. Referring specifically to  FIG. 3 , a bottom wall  45  of the drain trim holder  40  is sloped towards the center to create a funnel shape to ensure that the waste water that enters the drain trim holder will flow to the waste water pipe. There is a drain hole  44  on the bottom wall  45  of the drain trim holder  40 . The diameter of the drain hole  44  is substantially equal to the diameter of the waste water pipe that is to be inserted into the water drainage system. Upon installation, the drain hole  44 , the pipe hole  35 , and the receiving hole  36  are aligned to create a channel for wastewater collection and outflow. 
         [0056]    As shown in  FIGS. 2-4 , the water drainage system may also include a drain plate  18  and mounting screws  16 . The drain plate  18  may be used to cover the drain trim holder  40 . The drain plate  18  has multiple openings through its body, allowing flow of water into the water drainage system. The drain plate  18  may be pressure fit into the drain trim holder  40  after the drain trim holder  40  has been cut or lifted to the appropriate height of the finishing surface. The mounting screws  16  may attach the drain plate holder  40  to the pipe-capturing member  15 . As shown in  FIG. 3  and  FIG. 4 , there are adjustment holes  42  in the drain trim holder  40  and vertical screw holes  26  in the pipe-capturing member  15 . The diameter of the adjustment holes  42  are significantly larger than the diameter of the mounting screws  16  so that the position of drain trim holder  40  may be adjusted for the ideal location of the drain trim plate. From a top view, the drain plate  18  and the drain trim holder  40  may be a square shape. Upon installation, the drain trim plate  18  is fit into the top of the square drain trim holder  40  which is secured with the mounting screws  16  to pipe-capturing member  15 . 
         [0057]    As indicated above, it is preferred that the tubular section  22  of the pipe-capturing member  15  is inserted into the receiving hole  36  of the lower drain body. It is also preferred that the lower drain body  14  and the pipe capturing member  15  are attached with adhesives. Similarly, a wastewater pipe may be inserted into the interior of the pipe-capturing member  15  and attached to the pipe-capturing member  15  with adhesives. It should also be noted that adhesives may not be the only approach to join the three structures. For example, sonic-welding, as well as other methods, may also be utilized as long as effective attachment may be obtained. 
         [0058]    In terms of materials, the various components of the water drainage system may be made from same or different materials. It is desirable that the materials are waterproof, durable, robust, easy to mold, and relatively inexpensive. The materials that may be used include but are not limited to: metal, rubber, and plastic such as, but not limited to, polyethylene terephthalate (PET), polyethylene (PE), high-density polyethylene, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), high impact polystyrene (HIPS) and polycarbonate (PC), or some combination thereof. The preferred material for making the lower drain body  14  and the pipe-capturing member is PVC. 
         [0059]      FIGS. 5  A-H provide a full illustration of the pipe-capturing member  15 , wherein  FIG. 5A  is a top perspective view,  FIG. 5B  is a top view,  FIG. 5C  is a bottom view,  FIG. 5D  is a front view,  FIG. 5E  is a back view,  FIG. 5F  is a first side view,  FIG. 5G  is a second side view,  FIG. 5H  is a sectional side view. 
         [0060]      FIGS. 6  A-H provide a full illustration of the lower drain body  14 , wherein  FIG. 6A  is a top perspective view,  FIG. 6B  is a top view,  FIG. 6C  is a bottom view,  FIG. 6D  is a front view,  FIG. 6E  is a back view,  FIG. 6F  is a first side view,  FIG. 6G  is a second side view, and  FIG. 6H  is a sectional side view. 
         [0061]      FIG. 7  is an exploded sectional view of an alternative embodiment of the water drainage system of the present invention. The embodiment shown in  FIG. 7  shares significant similarities with the embodiment shown in  FIGS. 1-6 . In addition, this embodiment provides certain features that are in some aspects more advantageous. 
         [0062]    Shown in  FIG. 7  are a drain plate  18 , a drain trim holder  51  having a stepped inner flange  53 , an inner connecting member  70 , a first busing  54 , a second bushing  57 , an outer capturing member  60 , a waterproof membrane  19 , a lower drain body  14 , an adaptor  80 , and an anchoring nut  32 . Here, the structures some components, such as the anchoring nut  32  and the drain plate  18 , are similar to the same elements shown in  FIGS. 2 ,  3 , and  4 . 
         [0063]    The lower drain body  14  encircles a receiving hole  36  having a generally uniform first diameter, a top part of the lower drain body  14  being a lower drain flange  28  that extends radially outwardly, the lower drain flange  28  having an upper surface sloped to the center of the receiving hole  36 , the lower drain body  14  further having a cylindrical section  21  below the lower drain flange  28 . 
         [0064]    The outer capturing member  60  has an outer capturing member tubular section  64  encircling an outer capturing member hole  66  and an outer capturing member top flange  63  that extends radially outward. The tubular section  64  of the outer capturing member  60  has an exterior diameter and an interior diameter. The outer capturing member top flange  63  is positioned on top of the tubular section  64  and has a sloped lower surface. The sloped lower surface of the outer capturing member top flange  63  is substantially parallel to the upper surface of the lower drain flange  28 . The tubular section  64  of the outer capturing member  60  may be inserted into the receiving hole  36  of the lower drain body  14 . The outer capturing member top flange  63  and the lower drain flange  36  of the lower drain body  14  hold flush and secure the waterproof membrane  19 , which covers a substrate medium. Different from the embodiment shown in  FIG. 2-4 , here the tubular section  64  of the outer capturing member  60  extends below a lower end of the lower drain body  14 . The lower part of the outer capturing member tubular section  64  is threaded. The adapter  80  and the anchoring nut  32  may be attached to the threaded part of the outer capturing member tubular section  64 , with the anchoring nut  32  preferably screwed to the threaded part. 
         [0065]    The inner connecting member  70  has an inner connecting member tubular section  71  encircling an inner connecting member hole  75  and an inner connecting member top flange  72  that extends radially outward. The inner connecting member tubular section  71  may be inserted through the drain trim holder  51  so that the inner connecting member top flange  72  rests on the stepped inner flange  53  of the drain trim holder  32 . The inner diameter of the hole in the drain trim holder  51  is modestly larger than the exterior diameter of the inner connecting member tubular section  71 , with a difference preferably ranges between 2 to 50 mm. With this feature, the inner connecting member  70  allows the drain trim holder  51  to be modestly repositioned when the inner connecting member  70  is inserted through the drain trim holder  51 . Such a feature may reduce work load to avoid tile cutting, if tiles are used. Similar to the weeping holes shown in  FIGS. 2-4 , there may also be weeping holes  17  through the inner connecting member tubular section  72 , wherein the weeping hole  17  may be used for the drainage of residue water. 
         [0066]    The first bushing  54  and the second bushing  57  are inserted into the outer capturing member hole  66 , with the first bushing  54  being positioned above the second bushing  57 . The first bushing  54  and second bushing  57  are made from flexible and waterproof materials such as rubber. In addition, the first bushing  54  and the second bushing  57  have circling protrusions that ensure capturing. The inner connecting member tubular section  71  may be inserted into the first bushing  54  and being secured by the first bushing  54 . A pipe may extend through the second bushing  57 . capturing member, the weeping holes having openings on the radial chamfer of the upper interior edge of the pipe-capturing member and having an angle to facilitate draining into the pipe hole, and the integral weeping holes in the pipe-capturing member are substantially parallel to the top surface of the upper flange of the pipe capturing member. 
         [0067]    The water drainage system may also include other structures to form a more comprehensive and complete design for improvement of a household drainage assembly. For example, the water drainage system may include a shower pan that may be combined with the pipe centering and membrane securing mechanisms such as the lower drain body  14  and the pipe-capturing member  15  ( FIG. 3 ) or the lower drain body  14  and the outer capturing member  60  ( FIG. 7 ). The shower pan is installed over a subfloor or an underlayment that in most cases comprises plywood or other support structures. 
         [0068]    On key component of the shower pan is the substrate medium  12  as shown in  FIGS. 1 and 4 . The substrate medium is made from durable and water-resist materials such as but not limited to: metal, rubber, and plastic such as, but not limited to, polyethylene terephthalate (PET), expanded polystyrene (EPS), polyethylene (PE), high-density polyethylene, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), high impact polystyrene (HIPS) and polycarbonate (PC), or some combination thereof. The preferred material for the substrate medium  12  is EPS. The substrate medium is molded to have a slightly sloped surface, wherein the lowest point in the shower pan coincides with the location of the inlet of the wastewater pipe. A waterproof membrane  19  covers the substrate medium  12  as shown in  FIGS. 1 and 4 , providing a separating layer between the substrate medium  12  and water flow. The waterproof membrane  19  is preferred to be self adhesive. However, other methods may be used to attach the waterproof membrane  19  to the substrate medium  12 . The waterproof membrane  19  has the same features. 
         [0069]    The shower pan may also include a curb completely or partially surrounding the substrate medium. The curb may be made from the materials identified above or plastic wood composite. It is desirable that the curb be made from water resistant materials. The curb is thicker than the substrate medium and as a combined structure the curb and the substrate medium define the contours of the shower pan. It is preferable that the waterproof membrane also covers the curb. In addition, the waterproof membrane may expand upward against the splash wall adjacent to which the shower pan is installed, providing an extensive waterproof surface. 
         [0070]    The waterproof membrane may be folded or cut to match the surfaces of the shower pan and the splash wall. The preferred method is to fold the membrane because such an approach does not leave gaps that may cause accumulation of moisture on the inner surfaces and in the inner voids. The splash wall, which may also be considered a part of the water drainage system, may provide the space needed for disposing the fold-up portion of the waterproof membrane that is not used to provide cover to the water drainage system. The splash wall may have a splash wall void behind it or between sub-layers of the splash wall. There are multiple ways to fold the waterproof membrane. The fold-up portion of the waterproof membrane may be folded into the splash wall void, keeping the appearance of the shower pan clean and neat, also preventing necessary cutting of the waterproof membrane. 
         [0071]    Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made only by way of illustration and that numerous changes in the details of construction and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

Summary:
The current invention discloses a water drainage system designed for securing a waterproof membrane as well as centering a wastewater pipe. The water drainage system has a coupling mechanism including a lower drain body and a pipe-capturing member. The lower drain body may be installed in a substrate medium, such as a shower pan, onto which a waterproof membrane would be fixed. The pipe-capturing member has two frusto-conical designs which allow the pipe-capturing member to be firmly asserted into the lower drain body and at the same time center and secure the wastewater pipe. The pipe-capturing member and the lower drain body each has a flange wherein the two flanges trap and secure the waterproof member in place. Additional structures such as a drain trim holder may also be adopted to allow easier adjustment. The current invention is particularly useful for shower pan drainage.