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FIELD OF THE INVENTION 
       [0001]    The invention relates to an external overflow device for use with sanitary ware, such as baths and the like. In particular, the invention relates to an overflow device operable to regulate a maximum water level in the bath or the like, thereby providing a flood prevention apparatus. 
       BACKGROUND TO THE INVENTION 
       [0002]    Sanitary-ware such as baths and sinks conventionally have an overflow opening or channel in the wall of the bowl or tub. The position of the overflow determines the maximum level to which water can be contained in the bathtub or sink bowl. Typically, the overflow is an opening which provides an outlet for excess water, such that flooding by overfilling the sink or the bath can be averted. The opening is generally connected to a waste system either by means of a channel formed in the body of the sink or bath or by means of a flexible hose interconnecting an overflow terminal and a terminal on the waste system. 
         [0003]    Such overflow systems are simple and well understood, but they do have some disadvantages. An overflow channel within the body of the bath or sink adds complexity to the structure and to the manufacturing process. A separate flexible hose arrangement uses a number of components and can be awkward to install and maintain. In addition, the waste opening in the wall of the bath or the sink presents potential hygiene problems and can be difficult to clean. In addition, the connection of the opening to the waste system may not be sized appropriately to remove the water at a sufficient rate to avoid the bath or sink overflowing thereby causing potential flooding. 
         [0004]    Progress has been made where concealed or external overflow arrangements are being used such that a hole through the body of a sink or bath is no longer required. Such arrangements connect an overflow system to a trap connected to the waste outlet of the bath or sink. 
         [0005]    In a commercial setting, for example in a hotel, overfilling a bath can be problematic, where bathrooms can be flooded if the bath is overfilled at great expense to the hotel owners. Therefore, using an external overflow can regulate the maximum fill level of a bathtub such that expensive repairs due to flooding and water damage can be avoided in a commercial setting; such repairs may run into thousands of pounds. Similarly, the risk of flooding also applies in a domestic setting, for example in a family bathroom. Therefore, better control of the maximum water level in a bathtub is desired. 
       SUMMARY OF THE INVENTION 
       [0006]    A first aspect of the present invention provides an overflow apparatus for a bath or the like, the overflow apparatus comprises: 
         [0007]    a first pipe section configured to attach to a first outlet port of a multi chamber waste trap, wherein the first pipe section comprises a first substantially vertical pipe section; and 
         [0008]    a second pipe section extending from a second outlet port of a multi chamber waste trap, wherein the second pipe section includes a second substantially vertical pipe section, wherein the first and second pipes are joined in continuous fluid communication by an inverted U-shaped passage, which includes a constantly open air valve at its summit, wherein the air valve is operable to control flow of water through the overflow system in a non-siphonic state. 
         [0009]    An apparatus according to embodiments of the present invention takes the overflow out of the bath whilst allowing the level of the water in the bath to be safely and consistently regulated. Accordingly, the present invention provides an external overflow system, where the overflow system is arranged to regulate the water level in the bath, is situated external to the bath, such that if the water level exceeds a predetermined maximum level the excess water will be removed. 
         [0010]    The permanently open air valve prevents the overflow system siphoning whole contents of the bath. Therefore, an overflow apparatus according to the present invention manages the water level in a bath to a maximum predetermined level as per regulation or as set by the level of the overflow system and also acts as a flood prevention mechanism. 
         [0011]    The overflow system may comprise vertical adjustment, such that the maximum level attainable inside the bath is adjustable. 
         [0012]    The overflow system may further comprise a deflector member operable to directionally guide fluid flow from the first pipe section to the second pipe section in the event that excess water needs to be drained from the sanitary ware product to which the overflow device is connected. 
         [0013]    The deflector member may include a baffle member, which in use is located between the air valve and the U-shaped passage such that water is not in direct contact with the air valve. 
         [0014]    The inverted U-shaped passage may be provided in a correspondingly U-shaped pipe section. 
         [0015]    The U-shaped pipe section may include a branch portion adjacent to the air valve, wherein the deflector and baffle element are receivable in the branch portion. As such the deflector and baffle member may be removed for ease of cleaning the U-shaped passage. 
         [0016]    The deflector and baffle member are operable to prevent direct contact between the air passing through the valve and fluid flowing through the pipes that provide the overflow system. 
         [0017]    The provision of a constantly open air valve is such that a siphoning effect is not created within the overflow system. The valve may be operable to close should water enter the valve. The configuration of the overflow system is such that water flow through the overflow system ceases when the water level of the bath and the water level in the first pipe are equalised. 
         [0018]    The overflow apparatus may further comprise telescopic vertical pipe sections. Accordingly, the maximum level of water in the bath tub may be adjustable or can be set to a maximum level. As such, the present invention provides a versatile overflow device that can be attached to products of varying sizes externally and if required in a concealed manner such that visible overflow openings through the sanitary ware are no longer required. 
         [0019]    The telescopic vertical section may comprise a pipe within a pipe arrangement, wherein the pipes can slide relative to each other to extend or reduce the length of the vertical pipe sections. 
         [0020]    A further aspect of the present invention provides a waste trap, in the form of a multi chamber drain, for a bath or the like, the waste trap comprising: 
         [0021]    a body defining at least a first and a second chamber therein; 
         [0022]    a first outlet port and a second outlet port each defined by openings into the body, wherein each of the first and second outlet ports are vertically and horizontally displaced relative to each other; and 
         [0023]    wherein the first outlet port is in fluid communication with the first chamber and the second outlet port is in fluid communication with the second chamber and wherein the first and second outlet ports are each connectable to an associated pipe section of an overflow system. 
         [0024]    Under a bath tub space is limited, therefore the waste trap associated with the overflow system is configured to be compact in height. The height of the waste trap is compact due to the arrangement of the chambers defined within the body and the arrangement of the first and second outlet ports. The position of each of the first and second outlet ports is such that the centre of each outlet port is displaced horizontally and vertically relative to the other. Therefore, the vertical dimension of the trap can be minimised. 
         [0025]    The body and the first chamber are connectable to an outlet of a sanitary ware product, for example a bath, wherein an inlet to the first chamber is provided by the outlet of the sanitary ware product. The first chamber is in direct fluid communication with the outlet of the sanitary ware product. 
         [0026]    The position of each of the first and second outlet ports may be such that the centre of each outlet port is displaced horizontally and vertically relative to the other. 
         [0027]    The waste trap may further comprise a partition within the body, wherein the partition defines separation of the first chamber from the second chamber, the partition includes an opening such that the first and second chambers are in direct fluid communication when the opening is open. 
         [0028]    The waste trap may further comprise a closure member, which can be engaged with the opening or disengaged from the opening such that when the closure member is engaged with the opening direct fluid communication between the first and second chambers is disabled and when the closure member is disengaged from the opening direct fluid communication between the first and second chambers is enabled. 
         [0029]    The closure member may comprise a seal operable to sealingly engage with a face of the partition about the opening to close the opening. 
         [0030]    The closure member may comprise, for example a clicker seal operable by displacement of the seal to engage with the opening in the partition between the first and second chambers. The clicker seal may operate by application of pressure to displace the closure member into sealing engagement with the opening and by pressure being applied to displace the closure member out of sealing engagement from the opening. 
         [0031]    Upon initially filling the bath with water, whilst the closure member is engaged with the opening, a first vertical pipe of an overflow system will be primed with water to the level of water in the bath. As the water level in the bath increases the closure member effectively acts as a conventional plug, but one which is offset from the bath outlet such that fluid entering the bath is in constant direct fluid communication with the first chamber. 
         [0032]    The waste trap may further comprise a third chamber. 
         [0033]    The first and second chambers may be horizontally oriented and the third chamber may be vertically oriented. 
         [0034]    The third chamber may be in fluid communication with the second chamber. 
         [0035]    The third chamber may be a vertical chamber, which is open at the bottom and in fluid communication with the second chamber, wherein the second chamber is located below the first chamber. 
         [0036]    The third chamber may comprise a third outlet port arranged to remove excess water to waste. 
         [0037]    The third chamber may provide a water seal. 
         [0038]    The third outlet port may be located at least 50 mm above the lowest point of the waste trap. 
         [0039]    A further aspect of the present invention provides an overflow apparatus for a bath or the like, the overflow apparatus comprises: 
         [0040]    a first pipe section, which in use extends from a first outlet port of a multi chamber drain, wherein the first pipe section comprises a first substantially vertical pipe section; and 
         [0041]    a second pipe section which in use extends from a second outlet port of a multi chamber drain, wherein the second pipe section includes a second substantially vertical pipe section, wherein the first and second pipes are joined in continuous fluid communication by an inverted U-shaped passage, which includes a constantly open air valve at its summit, wherein the air valve is operable to control flow of water through the overflow system in a non-siphonic state. 
         [0042]    An apparatus according to embodiments of the present invention takes the overflow out of the bath whilst allowing the level of the water in the bath to be safely and consistently regulated. Accordingly, the present invention provides an external overflow system and waste trap, where the overflow system is arranged to regulate the water level in the bath such that if the water level exceeds a predetermined maximum level the excess water will be removed. The permanently open air valve prevents the overflow system siphoning whole contents of the bath. Therefore, an overflow apparatus according to the present invention manages the water level in a bath to a maximum predetermined level as per regulation or as set by the level of the overflow system. The overflow apparatus also provides a flood prevention mechanism. 
         [0043]    The overflow apparatus may further comprise a deflector member operable to directionally guide fluid flow from the first pipe section to the second pipe section in the event that excess water needs to be drained from the system. 
         [0044]    The deflector member may include a baffle member, which in use is located between the air vent and the U-shaped passage such that water is not in direct contact with the air vent. 
         [0045]    The inverted U-shaped passage may be provided in a correspondingly shaped pipe section. 
         [0046]    The U-shaped pipe section may include a branch portion adjacent to the air valve, wherein the deflector and baffle element are receivable in the branch portion. As such the deflector and baffle member may be removed for ease of cleaning the U-shaped passage. 
         [0047]    The deflector and baffle member are operable to prevent direct contact between the air passing through the valve and fluid flowing through the pipes that provide the overflow system. 
         [0048]    The provision of a constantly open air valve is such that a siphoning effect is not created within the overflow system. The configuration of the overflow system is such that water flow through the overflow system ceases when the water level of the bath and the water level in the first pipe are equalised. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0049]    Embodiments of the present invention will now be described with reference to the accompanying drawings in which: 
           [0050]      FIG. 1  is a schematic representation of an exploded perspective view of an overflow apparatus according to an embodiment of the present invention; 
           [0051]      FIG. 2  is a schematic representation of cross-sectional view of a waste trap used with the overflow apparatus as illustrated in  FIG. 1 ; and 
           [0052]      FIG. 3  is a schematic representation of a cross sectional view of the vertically oriented pipe sections as illustrated in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0053]      FIG. 1  illustrates an exploded, perspective view of an overflow device  10  according to an embodiment of the present invention. The overflow device  10  includes a waste trap  12  and an overflow system  14 . 
         [0054]    In the illustrated example, the waste trap  12  includes a body  16 , which includes three outlet ports  18 ,  20 ,  22 . The body  16  encases two horizontal chambers  24 ,  26  and a vertical chamber  28  (see  FIG. 2 ). The arrangement of the chambers  24 ,  26 ,  28  will be discussed further below with reference to  FIG. 2 . 
         [0055]    The first outlet port  18  extends through the body  16  from a first horizontal chamber  24  and the second outlet port  20  extends through the body  16  from a second horizontal chamber  26 . The third outlet port  22  extends through the body  16  from a third, vertical chamber  28 . 
         [0056]    The waste trap  12 , configured according to an embodiment of the present invention, provides a compact unit, suitable for use in a location where there is restricted height between the underside of a bath and the floor/surface upon which the bath is mounted/supported. 
         [0057]    In the illustrated example, the depth/height of the waste trap  12  is smaller than conventional waste traps due to the relative positions of the first and second outlet ports  18 ,  20 . Both the first and second outlet ports  18 ,  20  extend from one face of the body  16  and each outlet port  18 ,  20  is displaced vertically and horizontally relative to the other such that the height/depth of the waste trap  12  can be as small as possible in order to fit into a restricted space under a bath, in the vicinity of the outlet/plughole. This arrangement of first outlet  18  and second outlet  20  also allows for relatively large bore pipes to be used such that the drainage of excess water can be done as relatively high-flow, reducing the likelihood that a siphon effect will be created. 
         [0058]    The waste trap  12  may or may not include a water seal. In the illustrated example, the minimum height of the waste trap  12  is determined by the minimum depth of water seal required. In the illustrated example, a vertical chamber  28  is provided in the waste trap  12 . The provision of the vertical chamber  28  creates a water seal. 
         [0059]    The third outlet port  22  extends through the body  16  from the vertical chamber  28 . The third outlet port  22  is located at a height, which ensures an adequate water seal is maintained. In the illustrated example, the water seal is provided by the chamber  28 , which is at least 50 mm deep. The third outlet port  22  is connected by suitable pipe connections  23  to a drain or waste system (not illustrated). 
         [0060]    The first outlet port  18  and the second outlet port  20  are each connected to an overflow system  14  that is made up of a number of pipe sections that are joined together to form a continuous flow path from the first outlet  18  to the second outlet  20 . 
         [0061]    Referring again to  FIGS. 1 and 2 , in the illustrated example a first substantially horizontal pipe section  30  connects at one end to the first outlet port  18  and at the opposite end to a first ninety-degree elbow section  32 . The first elbow section  32  facilitates the change in flow direction from horizontal to vertical and facilitates the effect of removing excess water from the bath in the event that the bath is overfilled. 
         [0062]    A first vertically oriented pipe section  34  connects the first elbow section  32  to a first leg  36  of an inverted U-shaped pipe section  38 . The second leg  40  of the inverted U-shaped section  38  connects to a second vertically oriented pipe section  42 . The second vertically oriented pipe section  42  connects to a second ninety-degree elbow pipe section  44 . The second elbow section  44  connects at one end to a second horizontal pipe-section  46 . The second end of the second horizontal pipe section  46  connects to the second outlet port  20 , which extends from the second horizontal chamber  26 . 
         [0063]    In the illustrated example, each of the pipe sections are joined together by screw fittings  48 . 
         [0064]    In the illustrated example, the inverted U-shaped pipe  38  includes a substantially horizontal hollow branch  50  extending out from the first leg  36  of the U-shape pipe section  38 . 
         [0065]    In the illustrated example, and with reference to  FIG. 3 , a deflector member  52  is included within the branch  50 . The deflector member  52  includes a curved surface  54 , which is oriented, in use, to create a continuous U-shaped flow passage from the first outlet  18  to the second outlet  20  in the event that the bath is overfilled. 
         [0066]    The deflector member  52  also includes a stepped baffle section  56 . The stepped baffle section  56  is displaced from, but adjacent to an air valve  57  provided at the top of the inverted U-shaped pipe section  38 . The baffle section  56  extends across the opening of the air valve  57  and is therefore operable to prevent air being sucked directly into the water flow as water passes through the overflow system  14 . 
         [0067]    The baffle section  56  acts as a barrier to prevent direct contact between air, entering the system via the valve  57  and water as it flows through the system. As such, the overflow device  10  according to an embodiment of the present invention operates under non-siphonic flow conditions. This means that, in the event that there is excess water in the bath, the removal of excess water will be controlled such that the bath is not inadvertently emptied as would occur if the overflow device  10  operated under siphonic conditions. 
         [0068]    At the top of the branch  50 , the air valve  57  is included to vent the flow passage to atmosphere at all times. The air valve  57  is configured to be permanently open, but is operable to prevent water escaping from the system should water enter the valve. Accordingly, the valve  57  includes a shut-off feature. 
         [0069]    The permanently open air valve  57  acts to accelerate water flow from the first outlet  18  to the second outlet  20  in the event that excess water needs to be removed from the bath, for example in the situation where the bath is overfilled. This arrangement prevents water flowing over the sides of the bath and minimises the risk of flooding a bathroom area. 
         [0070]    It will be appreciated that the internal bore of the pipes can be sized to allow a suitably high flow volume of water to be removed from the bath to prevent water over spilling the sides of the bath and flooding the floor below, whilst maintaining a maximum level of water in the bath. A suitable sized pipe may be 50 mm (2 inches) in diameter. 
         [0071]    By using the overflow system  10  according to an embodiment of the present invention, complete emptying of the bath is only possible, when the first, upper, chamber  24  is in fluid communication with the second, lower, chamber  26 ; that is the plug element is lifted or removed. 
         [0072]    In the illustrated example, the overflow device includes a support member  58  arranged to support the first and second horizontal pipe sections  30 ,  46  in a desired orientation and at a desired height such that the connections to other pipe sections  32 ,  44  remain secure and are not compromised as water flows through the system. Further supports or ties may be included to support or stabilise the pipe and elbow components making up the overflow device  10 . 
         [0073]    In the illustrated example, see  FIGS. 1 and 2 , the overflow device  10  includes a sealing mechanism that is operable to isolate the top chamber  24  from the bottom chamber  26  in order to fill the bath. An example of a suitable seal mechanism is a clicker plug mechanism  60  as illustrated in  FIGS. 1 and 2 . 
         [0074]    The clicker plug mechanism  60  includes a flange  62  which locates on the base  63  of the waste trap  12 . A sleeve  64  extends up from the flange  62  into which the clicker mechanism  60  is received. A closure member  66 , in the form of a clicker seal  66  and a carrier  68  are connected to a rod  70 , which is received in the sleeve  64 . Movement of the rod  70  relative to the sleeve  64  controls the operation of the clicker seal  66  relative to the sealing face of the partition wall  67  (see  FIG. 2 ) separating the first and second chambers  24 ,  26 . 
         [0075]    In the illustrated example, the clicker seal  66  engages with an opening  65  in the partition wall  67  between the first chamber  24  and the second chamber  26 . When the opening  65  is closed by the clicker seal  66  direct fluid communication between the first chamber  24  and the second chamber  26  is prevented. When the opening  65  between the first chamber  24  and second chamber  26  is sealed, by the clicker seal  66 , fluid flow from the first chamber  24  to the second chamber  26  is only via the overflow system of pipes  14  as described above. 
         [0076]    The clicker mechanism includes a disc  72 , which is located inside the bath and located adjacent to the outlet/plughole. The disc  72  is connected to the rod  70  such that by depressing the disc  72  the clicker seal  66  can be engaged with the opening  65  or disengaged from the opening  65 . 
         [0077]    As can be seen from  FIG. 1 , the appearance of the disc  72  resembles a conventional plug; however, the disc  72  does not behave as a conventional plug because whilst it covers the outlet, it never actively seals the outlet of the bath at any time. The plugging action is provided by the closure member, for example the clicker seal  66 , when it is in sealing contact within the waste trap  12  as described further below with reference to  FIG. 2 . 
         [0078]      FIG. 2  shows an example application of the waste trap  12  located under a bath  80 . The waste trap  12  is shown as a cross-sectional representation such that only the first and third outlet ports  18 ,  22  are visible in  FIG. 2 . 
         [0079]      FIG. 2  shows the relative placement of the first chamber  24 , the second chamber  26  and the vertical chamber  28 . The first chamber  24  and the second chamber  26  are both horizontal. A horizontal partition  67  separates the first chamber  24  from the second chamber  26 . The partition  67  includes an opening  65 , which allows fluid to flow from the first, upper, chamber  24  to the second, lower, chamber  26 . 
         [0080]    The clicker seal  66  (as described above) is configured to engage with or disengage from the opening  65  to allow or prevent direct fluid communication between the first and second chambers  24 ,  26 . Therefore, the plug is effectively external to the bath. In addition, the overflow device  10  is also effectively external to the bath. 
         [0081]    In the illustrated example, the opening  65  between the first and second chambers  24 ,  26  is open; therefore, the first and second chambers are in direct fluid communication. In this configuration, any water being put in the bath  80  shall flow directly to the waste system via the first and second horizontal chambers  24 ,  26 , and the third, vertical chamber  28 . 
         [0082]    When the seal  66  is clicked in place, with respect to the opening  65 , the first chamber  24  is isolated from the second chamber  26 . As such, flow between the first chamber  24  and the second chamber  26  is prevented and the bath  80  can be filled to a maximum water level. The maximum water level in the bath is regulated by implementing the function of the overflow system as illustrated in  FIGS. 1, 2 and 3 . 
         [0083]    In the illustrated example the third, vertical, chamber  28  defines a water seal, where a bottom section  75  of the vertical chamber  28  is open to the second chamber  26  such that the vertical chamber  28  and the second chamber  26  are in fluid communication. The vertical chamber  28  is also in fluid communication with a waste system (not illustrated) via the third outlet  22  which facilitates the output of water to a waste system (not illustrated). 
         [0084]    Upon filling the bath  80 , water enters the first chamber  24  via the bath outlet/plughole (Arrow A) and exits the first chamber  24  via the first outlet  16  from where it enters the first pipe section  30 . As the bath  80  continues to fill with water the water level in the first vertical pipe section  34  rises correspondingly with the water level in the bath  80 . The configuration of the overflow system  14 , according to an embodiment of present invention, is such that the height of the first vertical pipe section  34  controls/regulates the maximum depth of water in the bath  80 . Therefore, in the event that the water level in the bath  80  exceeds this predetermined maximum level, water will flow (arrow B) into the inverted U-shaped section  34  and shall be removed to the waste system via the second vertical pipe section  42 ,  44 , the second chamber  26 , the vertical chamber  28  and finally the third outlet port  18  to waste. 
         [0085]    The predetermined maximum water level is defined by a point in the bath  80  and a corresponding height of the first vertical pipe section  34 . In this manner, the water level in the bath  80  can be regulated and the risk of the bath  80  overflowing or flooding of the room containing the bath  80  can be avoided. 
         [0086]    The vented U-shaped pipe section  34  operates such that sufficient air is drawn into the fluid flow, by the action of water flowing through the U-shape pipe, to accelerate the flow through the overflow device  10 , whilst preventing a siphonic condition. The configuration of the overflow system ensures that the water level in the bath  80  is regulated to a maximum height as determined by the height of the first vertical pipe section of the overflow system. The arrangement of the constant open air valve ensures that a siphoning effect is prevented such that inadvertent emptying of the bath, whilst the seal is in place, is avoided. 
         [0087]    By adopting the overflow system according to an embodiment of the present invention the contents of the bath can be regulated to a predetermined maximum level whilst the seal is engaged and can be emptied completely via the waste trap only when the seal is disengaged from the opening in the partition between the first and second chambers. 
         [0088]    The maximum depth of water allowed in a bath may be regulated by a regulatory standard or it may be determined by the user. For example, in respect water conservation the user may wish to set the maximum level of water allowed in the bathtub to quite low. In this regard, an external overflow device  10  in accordance with an embodiment of the present invention may include adjustable vertical pipe sections, wherein the height of the first vertical pipe section determines the maximum level of water in the bath. The vertical pipe sections may include a telescopic pipe assembly, which allows the user or installer to adjust the height of the first vertical pipe section to a predetermined height, which represents the maximum level of water in the bath. The telescopic arrangement may include a pipe within a pipe in the vertical pipe sections, wherein the length of the vertical section can be adjusted by the inner pipe being pulled from the outer pipe in a telescopic manner. 
         [0089]    Referring to  FIG. 3 , the first vertical section  34  comprises two pipe sections  90 ,  92  and the second vertical pipe section comprises two pipe sections  94 ,  96  of similar lengths to the two pipe sections  90 ,  92  forming the first vertical pipe section. In the illustrated example, the upper pipe section  90 ,  94  slides (Arrow C) within the lower pipe section  92 ,  96  such that the height of the overflow system is adjustable. 
         [0090]    Alternatively, the overflow system may comprise vertical pipe sections  34 ,  42  of fixed height/length. For ease of installation the vertical pipe sections may be assembled as multiple parts, which may include screw fitting joints  48  as illustrated. 
         [0091]    Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention.

Summary:
A flood prevention apparatus for a sanitary ware product such as a bath or the like. The flood prevention apparatus comprises a multi chamber drain and an overflow apparatus. The multi chamber drain comprises a body defining at least a first and a second chamber therein. Openings into the body define a first outlet port and a second outlet port. Each of the first and second outlet ports are vertically and horizontally displaced relative to each other. The first outlet port is in fluid communication with the first chamber and the second outlet port is in fluid communication with the second chamber. The first and second outlet ports are each connectable to associated first and second pipe sections of the overflow apparatus. The overflow apparatus comprises a first pipe section configured to attach to the first outlet port and a second pipe section configured to attach to the second outlet port. The first and second pipe sections provide substantially vertical pipe sections. The first and second pipe sections are joined in continuous fluid communication by an inverted U-shaped passage, which includes a normally open air valve at its summit. The air valve is operable to control flow of water through the apparatus in a non-siphonic state.