CA1220002A - Water-conserving toilet - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A water-conserving toilet is disclosed and includes a bowl for receiving waste and a waste outlet extending laterally from the bowl and defining a first, shallow trap arranged so that a relatively shallow body of liquid is normally retained in the bottom of the bowl for preventing gaseous flow through the trap. A flush system is provided and is arranged, when operated, to deliver a charge of flushing liquid into the bowl in a direction to cause said body of liquid to be dis-charged through said outlet. An enlarged chamber commun-icates with said bowl outlet for receiving waste from the bowl. An outlet extends outwardly from the chamber and is adapted for connection to a sewer inlet. The chamber outlet defines a second trap of substantial height capable of preventing reverse flow of sewer gas into the chamber in use. The toilet also includes means communicating with the chamber and adapted to relieve increase in gas pres-sure caused by liquid entering the chamber from the bowl whereby back pressure resistance to flushing of liquid from the bowl is reduced.

Description

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This :invention rclates generally to flush-type toilets.
Conventlonal toilets of this type are wasteful of water in that a large volume of flush-water is required for satisfactory operation. Typically, a conventional domestic toilet requires 4 or 5 gallons for each flush.
Also, at least in~the case of a domestic toilet a rela-tively large holding tank for flush water must be provided in the toilet itself; this makes for a relatively large and bulky toilet which is difficult -to m.ake aesthetically acceptable.
Prlor art attempt~ at reducing tlle volume of flush-water required have generally proved unsatisfactory for the reason that they have usually attempted to mexely restrict the volume oE the flush-water in the toilet tank rather than to approach the more rundamental problem of toilet design. Thus, a conventional flush toilet operates on the principle that a syphon is set up by the flush-water delivered ir:to the toilet bowl, so that the contents of the bowl are in effect sucked out by the syphon. In order for this syphon effect to be produc~d it is essential that a relatively large volume o~ ~lush-water be used. In other words, the need for a large volume of flush-water is inherent in the design o~ a conventional toil~t.
An object o~ the present invention is to pro-vide an improved toilet based on novel design con~i~era-tions which allow substantially smaller volumes oE
flush-water to he used.
The toilet provided by the invention includes a bowl for receiving waste and a waste outlet extendiny ~L2Z~

laterally from the bowl and defininy a first, shallow trap arranged so that a relatively shallow body of liquid is normally retained in the bottom of the bowl for preventing gaseous flow through the trap. A flush system is provided and is arranged, when operated, to - deliver a charge o flushing liquid into the bowl in a direction to cause said body of liquid to be dis-charged throuyh said outlet. An enlarged chamber com~
municates with said bowl outlet for receiving waste from the bowl. An outlet extends outwardly from the chamber and is adapted for connection to a sewer inlet.
The chamber outlet defines a second trap of substantial height capable of preventing reverse flow of sewer gas into the chamber in use. The toilet also includes means communicating with the chamber and adapted to relieve increasing gas pressure caused by liquid entering the chamber from the bowl, whereby back pressure resis~
tance to flushing of liquid from the bowl in reduced.
I~ order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which illustrate a number of embodiments of the invention by way of example, and in which:
Fig. 1 is a perspective view, partly exploded, of a toilet according to a preferred embodiment of the Z~
invention;
Fig. 2 is a longitudinal sectional view generally along line II-II of Fig. l;
Fig. 3 is a schematic illustration of the flush system of the toilet of Figs. 1 and 2;
Fig. 4 is a detail view of part of the flush system; and, Fig. 5 is a ~lan view of an alternative flush actuating mechanism according to a further embodi-ment of the invention:
Referring first to Fig. 1, the toilet has a housing generally denoted 20 made up of a lower housing part 22 and an upper housing part,24 which'fit together at a joint line indicated at 26. The two housing parts are permanently sealed together by means of a suitable adhesive. Upper housing part 24 has an upwardly ex-tending rear portion 28 which has a xemovable top 30 and which houses a holding tank 32 for flush water and associated components of the flush system as will ~e more specifically described later. Forwardly of portion 28, the upper housing part 24 is formed with a toilet bowl opening 34 providing communication to a bowl 36.
A conventional toilet seat assembly, shown in an exploded position at 38, is fitted to the upper housing part ~4 so as to overlie the bow] opening 34.
In Fig. 2, the toilet bowl 36 is visible in sec-tion and it will be seen that the bowl communicates with a waste outlet 40 which extends laterally from the bowl. Out-let 40 in turn communicates with an enlarged chamber defined by a waste holding tank 42 which is disposed at the rear of the toilet housing, below the f'lush water tank 32. Adjacent its lower end, the holding tank communicates with an outlet 44, the outer end portion 46 of which is adapted to be connected to a sewer inlet generally in the manner of a conventional toilet.
Before describing the toilet in more detail, .it may be convenient to note that, not only the housing 20, but also the remaining principal components of the toilet are, where possible, made of a suitable plastic material, eg. by vacuum forming, and are secured to-gether by a s.uitable adhesive. Thus, the toilet bowl 36 is a vacuum plastic moulding having an inwardly turned lip 48 around its upper edge, which nests behind a downwardly directed flange 50 of the upper housing part 24 extending around the toilet bowl opening.
Lip 48 is secured to the rear face of flange 50 by adhesive. It will be seen that the lip defines a recess 52, the purpose of which will be described later~
At this point, it may be convenient to note that the toilet bowl and/or the upper housing part 24 will be pro~ided with suitable supports for carrying the weight of a person seated on the toilet; however, for clarity of illustration, these supports have not been shown in the drawings.
As can best be seen in Fig. 1, the bottom of the toilet bowl is shaped to define a trough-shaped depression 54 which extends generally from front to back of the bowl. At its rear end, ~epression 54 com-municates with the bowl outlet 40 by way of a coupling 56 ~Fig. 2) integrally formed on the bowl. The coupling 56 has an annular recess 5~ in its outer end which re-ceives an length of pipe 60 forming sa.id waste outlet 40. A

similar coupling 62 is Xormed on the waste holdin~ tank and receives the opposite end of pipe 60. The pipe is secured into the tube couplings using a conventional solvent-type adhesive.
When the toilet is in use, a relatively shallow body of liquid will normally remain in the bottom of the bowl at a level indicated by reference numeral 64 in Fig. 2. This level will be determined by the angular inclination of the bowl outlet 40 and is chosen so that the outlet defines a first trap in which a relatively shallow body of liquid is normally retained for preventing gaseous communication through the trap.
Thus, it will be seen that level 64 is always slightly above the portion 36a of the bowl at the top of outlet 40. This will pre~ent reverse flow of any unpleasant odours from the holding tank 42. At the same timet it is to be noted that this first 'crap formed by out-let 40 does not form the main sewer gas trap of the toilet and need not therefore be of substantial height.
As a result, the volume of the residual body of liquid in the toilet bowl is relatively small and can be readily flushed from the bowl as will be described.
Flush water is delivered to the bowl through a series of openings in the wall of the bowl at the front end of the trough-shaped depression 54 referred to in connection with Fig. 1. One of these openings is visible at Ç6 in Fig. 2; the remaining openings are disposed in horizontal alignment with opening 66.
Water is delivered to the opening 66 through a pipe 68 31 2~

(see also Fig. 1) from the flush mechanism of the toilet (to be described). Pipe 68 is fitted over a spigot 70 (Fig. 2) which projects from a moulded housing 72 on the exterior surface of bowl 36. Housing 72 defines a chamber behind the opening 66 in which water delivered from the flush mechanism is distrlbuted to the openings and issues into the bowl. It will be appreciated that the water leaving openings 66 will be directed towards the bowl outlet 40 and will accordingly tend to flush waste in the'bowl directly into the outlet. The water is under pressure ~as will be described) and has been found iII practice to readily clear the bowl using a minimum volume flush. For example, in practical tests, a flush volume of 3 quarts (Imperial) has been found to be adequate over an extended period of time of ordinary domestic use of the toilet.
P~insing of the toilet bowl is provided for hy a rinse line 74 (Fig. 2) connected into the main flush water line 68 by a T-piece 7~ (see also Fig. 1). Line 74 is connected to an arcuate sha,ed rinsing element 78 (see Fig. 1) which is secured by adhesive in the recess 52 behind the lip 48 of bowl. Element 78 is in the form of a length o~ pvc tubing closed at its ends and having a series of holes through which water can ~e directed downwardLy over the surface of the bowl as indicated by the arrows 80 in Fig. 2. It is o course to be understood that, while only a short length of tubing has been shown in the drawings, in practice, the rinse element could extend over suhstantially the whole of the circumference of the toilet bowl.

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I~ith continued reference to Fig. 2, it ~7ill be remembered that the waste outlet 40 is connected to a coupling 62 on the holding tank 42 of the toilet.
Tank 42 is a specially shaped plastic tank disposed inside the housing 20 of the toilet. ~he tan}; is of rectangular shape in plan and fills the entire width o~ the rear portion of the housing. The flush system o the toilet is generally indicated at 82 in Fig. 2 and, as can be seen, is mounted on the top of the tank.
Adjacent the bottom of its front wall, tank 42 includes an integral coupling 84 similar to the couplings 56 and 62 described previously. The holding tank outlet 44 exkends outwardly ~rorn this coupling.
As can be seen, outlet 44 is generally J-shaped and includes a straight pipe section 86 and two 90 elbows 88 and 90 joined to one anothe~ by a coupling sleeve 92 and joined to the outer end of pipe 86 by an integral coupling collar 94 on the inner end of elbow 88. At its outer end, elbow 90 is fitted with a short pipe section 96 which couples to a 45 elbow 98 ~itting with an integral mounting plate 100 which extends transversely through a recess 102 in the toilet housing (see also Fig. 1). Plate 102 has openings for receiving securing bolts, one of which is indicated at 104, for securing the toilet to a floor surface. Plate 100 has a recess 106 in its under surface for receiving a flanged sewer inlet - connection such as that indicated yenerally at 108 in Fig. 1. Thus, the portion of the toilet providing a connection to the sewer inlet is of the form conven-tionally used on domestic toilets in order that the ~%~

toilet provided by the invention may be readily coupled to an existing sewer system in exactly the same fashion as a conventional toilet. The only other external connection required for the toilet will be the water inlet pipe, which will be a standard 1/2 inch or 3/4 inch copper pipe as will be described.
The pipe 60 of the bowl outlet and the pipes 86 and 96 and the elbows 83 and 90 of the holding tank outlet 44 are all standard ABS plastic sewer pipe fittings and are secured in place using normal A~S
solvent adhesiv~.
The holding tank outlet 44 defines a second txap of the toilet which is of substantial height com-pared with the height of the first trap defined by the bowl outlet. Thus, the static liquid level in the second trap is represented by the lines indicated at 110 in Fig. 2 and the trap height is represented by dimension 8 and provides the "legal" sewer trap height required by plumbing codes for preventing reverse flow o~ sewer gas into the toilet.
Holding tank 42 and the associated outlet 44 are dimensioned so that the volume of liquid con-tained therein in the static condition shown in Fig. 2 is substantially in excess of the vo]ume of liquid discharged from the bowl at each flush. This avoids any possibility that a syphon effect might be set up - which could tend to empty the second trap, as might occur if the holding tank were too small. Thus, the toilet is designed so that, when the bowl is flushed, the volume of liquid which passes into the holding ~ 0~V~ , tank ~ill be sufficien~ to cause merely an overflow of liquid from the second trap into the sewer rather than a full scale flushing effect intended to generaté
a syphon as in the case of a conventional toilet.
For the same reason, the holding tank is fitted with a flexible diaphragm which extends across the tank above the level at which liquid enters from the bowl. This diaphragm is designed to flex upwardly to accommodate air displaced in the holding tank as liquid enters from the bowl. In this particular embodiment, the diaphragm is indicated at 112 and is - in the ~orm o a dome-shaped ~accuum moulded flexible sheet fitted acxoss a circular opening in the top wall 114 of holding tank 42. The peripheral margin of the diaphragm i5 sealed in gas tight fashion to wall 114 by means of a suitable adhesive. The diaphragm is shown in its normal static position in full line and in its-position of maximum flex in chain dotted line.
The diaphragm is dPsigned so that the air displacement which can be accommodated by movement of the diaphragm from its full line position to its chain dotted line ` position exceeds the maximum anticipated volume of air which would be displaced when the toilet is in operation.
Thus, in practice, it is likely that the diaphragm will probably not move fully to its chain dotted line positlon.
The diaphragm is made of pvc and is sufficiently thin and flexible as to present rninimal resistence to flexing. A
relatively dense slug of adhesive is provided in the center region of the diaphragm as indicated a 116 in order to ensure that the diaphragm will naturally re-turn to its full line position when all of the liquid : .

and waste material from the bowl 36 has entered the-holding tank 42.
Diaphragm 112 is important to the proper operation of the toilet in two respects. Firstly, it ensures that the air in holding tank 42 presents mini mum resistence to flushiny of li~uid and waste from the toilet bowl into the holding tank. Were it not for khe presence of the diaphragm the aix in the holding tank would act as a buffer tending to resist inflow of liquid from the bowl. ~hus, the diaphragm generally makes it easier to ~lush the bowl and allows less water to be used. Secondly, the diaphragm further reduces any likelihood of a syphon effect occuxring at the second trap. Thus, if there were no diaphragm, the buffering effect of the air in the holding tank would tend to cause the liquid in the second trap to be pushed through the trap and might tend to promote a syphoning effect - which could empty the trap. In contrast, the liquid which enters the holding tank from the bowl in the ~0 toilet being described, merely causes a gradual over-flowing of liquid from the second trap, with no syphoning effect. Solid waste and tissue in the holding tank will tend to be broken down while standing in the holding tank and due to turbulence in the liquid (as a result ~f subsequent flushes),before passing into the sewer.
ReferenGe will now be made to Figs. 3 and 4 =
in describing the flush system o~ the toilet. Fig. 3 shows the flush water tank 32 discussed pxeviously.
The tank is of generally cylindrical shape and comprises two end caps 118 and 120 fitted in air-tight fashion to ~Z2~

a cylindrical body 1~2. End cap 118 is fitted with an air operated flush valve 124 which is shown in more detail in Fig. 4. End cap 120 is fitted with a coupling for a water inlet pipe 126 from the ~ain water supply of the dwelling in which the toilet is installed. End cap 120 also has a tapping ak~the top for an air line 128.
Air line 128 is co~nected to the flush valve 124 and includes a standard air check valve 130 and an adjustable flow control valve 122. A further air-line 134 bypasses the valves 130 and 132 and is fitted with an on/off air valve 13k which is operated by a handle 138 in the manner o~ a conventional toilet ~lush handle. Handle 138 is visible at the rront of the upper extension of the rear portion of the toilet housing in Fig. 1. Valve 136 is spring bi~ædtO the "off" position in which it is shown.
Referring now to Fig~ 4, the air operated flush valve 124 includ~s a body 140 having a cylindr~cal exten-sion 140a at it$ inner end which is fitted into anopening 142 in the end cap 118 of cylinder 32. A water passage-way 144 extends through extension 14Qa to the interior of cylinder 32 and is surrounded by a valve seat 146 inside the cylinder. Outside the cylinder, the passage-way is fitted with a coupling 148 to which is attached the main water flush pipe 68 shown in Figs. 1 and 2.
A conical valve member 150 normally seats against valve seat 146 and is carried by a valve stem 152 which ex-tends through valve body 140 and is fitted adjacent its outer end with a spring 154 arranged to normally bias valve member 150 against the seat 146. The outer end of valve stem 1S2 is fitted with an end cap 156 which is disposed in a recess 158 in the end of the valve body.

~zv~z A diaphragm lG0 extends across the outer end of the recess and bears ayainst cap 1S6. Finally, the diaphragm is surmounted by a dome-shaped cover 162 having a projecting spigot 164 to which is attached the air line 128 referred to in Fig. 3. Thus, lt will be appreciated that, if pressurized air is delivered to valve 124 along line 128, the diaphragm 160 will bow inwardly as indicated in chain dotted line and ' will cause the valve stem 152 to move upwardly and lift the valve member 150 o its seat 146 and provide fluid communication bet~Jeen the interior of cylinder 32 and the 1ush water line 68.
Re~erring back to Fig. 3, the sequence o~
operation of the flush mechanism will now be described.
Assuming that cylinder 32 is initially empty, water'will, enter through line 126 and will begin to fill the .
cylinder. As the cylinder fills up (from the bottom) air will be trapped above the water and will be pres-surized to an extent depending on the mains pressure of the water entering the cylinder. When the air above the water is fully pressurized, inflo~ of water will stop~ Not only the air above the water will be pressurized but al~ the air in line 128 and in the portion of line 134 between line 128 and valve 136.
Check valve 130 will prevent pressurized air from reaching the diaphragm of flush valve 124. If the ~lush handle 138 is now operated opening valve 136, the pressurized air in line 134 will be applied to the diaphragm 160 o the 1ush valve and the valve will open. The pressurized air in cylinder 32 will then eject the water under pressure through the main flush 3~2~

line 68. This pressurizéd water will be delivered directly to the fxont end of the trough~shaped depres~
sion 54 in the toilet bowl as described previously and will flush any waste in the toilet bowl into the holding tank also as described. At the same time, a rinsing action will occur in the bowl through rinse line 74. It will be noted that line 74 is of smaller diameter than the main ~lush line 68 so that a lesser volume of flush water will be used or rinsing than for the main flush action.
When the flush handle 138 is released, valve 136 will close, but the diaphragm 160 of flush valve 124 will be held in the pressurized position because the pressurized air will be trapped in line 134 due to the fact that 136 will be closed. However, flow con-trol valve 132 will set to allow air to bleed back into the cylinder through line 128 so that the flush valve will close progxessively. This will ensure that, rather than being abruptly cut off, the flow of flushing 26 water will gradually diminish so as to ensure that a residual body of water will remain in the toilet bowl.
As soon as the flush water begins to leave cylinder 52 it will be replaced by water from line 126 so that the tank will immediately repressurize.
Fig. 5 illustrates an alternative mechanism for operatiny a pressurized water tank of the form des-cribed with reference to Fig. 3. Thus, in the Fig. 5 embodiment, the water tank would be essentially the same and tank 32 but with different connections;
accordingly, the tank has been shown merely diagram-matically in Fig. 5 at 32'. The tank has a siAgle inlet 166 for water and the single, larger diameter outlek 168.
In this embodiment, the flush mechanism includes a seat-operated rotary valve 170 having an inlet 172 connected to a water supply and a corresponding outlet 174 connected to the cylinder inlet 166. The flush water outlet from cylinder 32' is connected to a second inlet 176 of valve 170 and a corresponding outlet 178 is connected to the main flush pipe 63 o~ the toilet.
Valve 170 is operated by a shaft 180 which is turnable in the valve housing to o~erate a valve member (not shown~ for controlling communication between the inlets and outlets of the valve as will be described.
Shaft i80 forms the hinge pin ~or the toilet seat assembly 38' of the toilet and is keyed to sea~ 182 of assembly 38' by lugs 184 which project from the shaft into corresponding xecesses in the seat so that shaft 180 is turned by raising and lowering seat 182.
The valYe member of valve 170 is designed so that, when the seat is in the down position in which it is show~ the water supply line 172 is closed while the flush line 176 is open and communicates with outlet 178 for delivering flushing water to the toilet. When the seat is raisedl the connections are reversed so that the water supply inlet 172 is open allowing water to flow through the valve to tank 32' while the flush watex inlet connection 176 of the valve is closed.
Visualizing the toilet in use, it will be appreciated that, when the seat is raised by a person wishing to use the toilet, water wlll flow through valve 170 and into the tank 32l, pressurizing the same rea~y or flushing. When the person has finished using the toilet o~ ~

and closes the seat the flush line from the tank will open and deliver flush water to the toilet bowl.
It will of course be apprecia~ed that the preceeding description relates to specific embodiments of the lnven~ion only and that many modifications are possible within the broad scope of the invention. For example, while twc specific examples of flush systems have been described, other alternatives are possible.
Preferably, the flush water is pressurized to achieve a high pressure action. However, it might even be possible to flush the toilet using a conventional water tank and gravity feed flush system. Another possibility would be to use a two tank flush ~ystem in which the two tanks would alternately fill and be used for flushing so that one tank would always contain water under pres-sure and would be ready to be used instantly when a ~lush was required.
It is also to be noted that many other modi-fications are possible. For example, referring to the holding tank 42, the diaphragm 112 need not be mounted in the top wall of the tank as described. It could, for example, extend across the tank below the top wall. It would even be possible to mount the diaphragm in a vertical wall of the tank although in that event special means would have to be provided to return the diaphragm to its rest position. Also, it should be noted that, while the speci~ic description refers to a toilet constructed primarily of plastic moulded components, there is no limitation in ~his.
Conventional ceramic manufacturing techniques could be applied to the toilet provided by the invention.

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A toilet which includes:
a bowl for receiving waste;
a waste outlet extending laterally from the bowl and defining a first, shallow trap arranged so that a re-latively shallow body of liquid is normally retained in the bowl for preventing gaseous communication through the trap;
a flush system arranged, when operated, to deliver a charge of flushing liquid into the bowl in a direction to cause said body of liquid and waste to be discharged through said outlet;
an enlarged chamber communicating with said bowl outlet for receiving waste from said bowl;
an outlet extending outwardly from said chamber and adapted for connection to a sewer inlet, said chamber outlet defining a second trap of substantial height cap-able of preventing reverse flow of sewer gas into said chamber in use; and, means communicating with said chamber and adapted to relieve increasing gas pressure caused by liquid entering the chamber from the bowl, whereby back pressure resistance to flushing of liquid from the bowl is reduced,

2. A toilet as claimed in claim 1, wherein said chamber defining means comprises a holding tank, and wherein said gas pressure relieving means comprises a flexible diaphragm which is sealed to the tank in gas tight fashion and which is adapted to flex upwardly and accommodate gas displaced as liquid waste enters the tank from the bowl.

. A toilet which includes:
a bowl for receiving waste;
a waste outlet extending laterally from the bowl and defining a first, shallow trap arranged so that a relatively shallow body of liquid is normally retained in the bowl for preventing gaseous communication through the trap;
a flush system arranged, when operated, to deliver a charge of flushing liquid into the bowl in a direction to cause said body of liquid and waste to be discharged through said outlet;
a waste holding tank communicating with said bowl outlet for receiving waste from said bowl;
a holding tank outlet extending outwardly from said tank and adapted for connection to a sewer inlet, said holding tank outlet defining a second trap of sub-stantial height capable of preventing reverse flow of sewer gas into the holding tank in use;
the holding tank and second trap being arranged to contain a volume of liquid substantially in excess of that discharged from the bowl at each flush; and, a flexible diaphragm extending across the holding tank above the level at which liquid enters from the bowl and sealed to the tank in gas-tight fashion, said diaphragm being adapted to flex upwardly and accommodate air displaced as liquid enters the tank from the bowl, so as to minimize air resistance to flushing of liquid from the bowl.

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4. A toilet as claimed in claim 1 or 3, wherein the bowl has a trough-shaped depression extending generally from front to rear of the bowl, wherein said outlet is disposed at the rear end of said depression, and wherein the flush system is arranged to deliver flush liquid into the bowl at the front end of said depression in a direction towards said outlet.

5. A toilet as claimed in claim 3, wherein the waste outlet from the bowl is defined by a inclined pipe extending upwardly from an outlet opening in the bowl to an inlet opening in the holding tank and arranged at an inclination such that the portion of the bowl defining the top of said opening is maintained below the level of said relatively shallow body of liquid in the bowl.

6. A toilet as claimed in claim 3, wherein said flexible diaphragm is provided in a top wall of the holding tank, and wherein the diaphragm is weighted so that it normally assumes a depressed position in the tank.

7. A toilet as claimed in claim 1 or 3, wherein said flush system includes a main flush pipe connected to said bowl and a bowl rinsing pipe which is of smaller diameter than said main flush pipe and which is arranged to deliver flush liquid to a position adjacent the upper edge of the bowl for rinsing the bowl surface.

8, A toilet as claimed in claim 1 or 3, wherein said flush system includes a closed water tank; means for delivering water to said tank under pressure directly from a main supply, whereby air trapped in the tank is pressurized by incoming water; valve means operable by a person using the toilet for releasting the pressurized water from the tank; and conduit means for delivering pressured water from the tank to the bowl for flushing.

9. A toilet as claimed in claim 1 or 3, wherein said flush system includes a closed water tank; means for delivering water to said tank under pressure directly from a main supply, whereby air trapped in the tank is pressurized by incoming water; valve means operable by a person using the toilet for releasing the pressurized water from the tank; and conduit means for delivering pressured water from the tank to the bowl for flushing, and wherein said valve means is an on/off air valve biased towards its off position, and wherein the flush system further comprises an air operated flush valve which is normally closed and is adapted to open under the influence of air pressure to release flush liquid to the bowl; a first air line coupling said air operated flush valve through said on/off air valve with pressurized air trapped in the tank; and a second air line bypassing said on/off valve and arranged to allow pressurized air applied to said flush valve to bleed back to the tank when the on/off valve is closed, whereby the flow of flush liquid to the bowl is progressively terminated.

10. A toilet as claimed in claim 1 or 3, wherein said flush system includes a closed water tank; means for delivering water to said tank under pressure directly from a main supply, whereby air trapped in the tank is pressurized by incoming water; valve means operable by a person using the toilet for releasing the pressurized water from the tank; and conduit means for delivering pressured water from the tank to the bowl for flushing, and wherein said valve means is an on/off air valve biased towards its off position, and wherein the flush system further comprises: an air operated flush valve which is normally closed and is adapted to open under the influence of air pressure to release flush liquid to the bowl; a first air line coupling said air operated flush valve through said on/off air valve with pressurized air trapped in the tank; and a second air line bypassing said on/off valve and arranged to allow pressurized air applied to said flush valve to bleed back to the tank when the on/off valve is closed, whereby the flow of flush liquid to the bowl is progressively terminated, and wherein said second air line includes an adjustable flow control valve for varying the speed of bleed back of air to the tank.

11. A toilet as claimed in claim 1 or 3, wherein said flush system includes a closed water tank; means for delivering water to said tank under pressure directly from a main supply, whereby air trapped in the tank is pressurized by incoming water; valve means operable by a person using the toilet for releasing the pressurized water from the tank; and conduit means for delivering pressurized water from the tank to the bowl for flushing, and wherein said valve means is coupled to a seat of the toilet and is operable to allow water to flow into the tank when the seat is up and to flow from the tank for flushing the toilet when the seat is closed.

12. In a toilet having a bowl for receiving waste and a flush system for delivering flush liquid to the bowl, the improvement comprising:
a waste outlet extending laterally from the bowl and defining a first, shallow trap arranged so that a relatively shallow body of liquid is normally retained in the bowl for preventing gaseous communica-tion through the trap;
a waste holding tank communicating with said bowl outlet for receiving waste from said bowl;
a holding tank outlet extending outwardly from said tank and adapted for connection to a sewer inlet, said holding tank outlet defining a second trap of substantial height capable of preventing reverse flow of sewer gas into the holding tank in use;
the holding tank and second trap being arranged to contain a volume of liquid substantially in excess of the liquid volume discharged from the bowl at each flush; and, a flexible diaphragm extending across the holding tank above the level at which liquid enters from the bowl and sealed to the tank in gas-tight fashion, said diaphragm being adapted to flex upwardly to accommodate air displaced as liquid enters the tank from the bowl.