Domestic households, hotels and restaurants etc. typically use large amounts of potable town water. Moreover, this water is subsequently discharged into the sewer system immediately after use. Existing systems are thus very wasteful of town water and also place a heavy load on sewage treatment. This poses a threat to potable water supplies and further generates excessive quantities of sewer effluent which is discharged back into the environment.

SUMMARY OF THE INVENTION It is therefore an object of this invention to ameliorate the aforementioned disadvantages and accordingly there is disclosed a water supply and purification system comprising a first storage reservoir for purified grey water, a second storage reservoir for contaminated grey water and a grey water purification means connected between said first and second reservoirs, means for supplying purified grey water from said first reservoir for usage, means for discharging contaminated grey water from said usage (excluding toilet usage) to said second storage reservoir, means to supply said contaminated grey water from said second reservoir to said purification means for processing thereof, means to replenish said first reservoir with purified grey water from said purification means and means to make up said first reservoir against any loss of grey water with additional water to said system.

The term "grey water" is used in this specification to indicate waste water from the use of the kitchen sink, hand basin, bath, shower, laundry or the like but excluding the toilet.

BRIEF DESCRIPTION OF THE DRAWING The attached figure 1 shows a schematic diagram of the currently preferred form of a grey water purification and recycling system according to this concept.

DESCRIPTION OF PREFERRED EMBODIMENT The system may comprise a processing tank 1 of say 125 litres, a purified grey water storage tank 2 of say 500 litres, and a contaminated grey water storage tank 3 of say 2000 litres. Preferably but not essentially the processing tank 1 is situated at ground level, the purified grey water tank 2 is located at the ceiling or roof level of a building and the contaminated grey water storage tank 3 is mainly below ground level.

Typical town water 4 is presumed to be clear and drinkable and in accordance with this invention is supplied only to the kitchen taps 5 and to a low level make up tap 6 (with float ball valve) in the purified grey water storage tank 2. Water from kitchen usage is passed first through a conventional grease trap 7 which retains substantially all the oil, grease and fat. This grey water is then discharged into the tank 3. All contaminated grey water from hand basin 8, bath/shower 9, and laundry 10 usage is also discharged to the storage tank 3 via conduits 11. Overflow from this tank 3 is discharged into the sewer system 12 as shown. Flush water from the toilet 13 is not recycled but rather is also discharged directly into the sewer system 12. Any rain water 14 collected from the building roof, garden and paths etc. is preferably discharged into the storage tank 3. When this storage tank 3 is close to full but before overflow a ball diversion device 15 directs any excess rain water to the storm water drain 16 to avoid unnecessary flow into the sewer.

When the processing tank 1 is activated pump 17 is also turned on to draw grey water from the storage tank 3 to fill the tank 1 through conduit 17A. After the tank 1 is filled to the required level as indicated by level switch 18 the pump 17 is turned off and the contaminated grey water therein is purified. Preferably the tank 1 operates using a process of electrolysis whereby an electric potential is applied between two or more electrodes (not shown) which are submerged in said tank. The chemical reactions at these electrodes produce bubbles of hydrogen and oxygen as well as floc. The floc binds with impurities in the water and is then carried with the bubbles up to the water surface where it can be collected and disposed of.

The bottom 19 of the processing tank 1 is preferably cone shaped to provide a low point for collection of any heavy sediment which cannot be flushed out from the top. A solenoid valve 20, is controlled by a central microprocessor 21 to discharge this sediment periodically.

The currently preferred operation of the processing tank 1 is more fully described in the applicant's co-pending Australian patent application 61885/98.

Typical processing time for a 125 litre tank would be about three hours. All processing procedures and the necessary sequences involved are preferably controlled by the central microprocessor 21. When the purification of the grey water is almost completed the controller 21 opens a solenoid control valve 22 to let previously purified grey water flow from the tank 2 into tank 1 through conduit 23 so that the floc floating in the cone shaped top 24 is displaced out through an overflow chute 25 to the sewer 12. When the processing is completed the controller 21 then turns on the pump 26 which discharges the purified grey water into the storage tank 2 through conduit 27. The water in this tank 2 is then supplied through conduits 28 for non-potable usage in the aforementioned hand basins 8, bath/shower 9, laundry 10 and toilet 13. When the level of purified grey water in the tank 2 reaches a predetermined maximum it is detected by a level switch 29 and the pump 26 is turned off.

Alternatively when the level of water in the processing tank 1 falls to a predetermined minimum as detected by level switch 30 the pump 26 is also turned off. As mentioned earlier a tap and ball float valve 6 is preferably provided in the tank 2 to enable town water 4 to be added as required to make up for any loss or short fall of purified grey water. Any excess purified grey water in tank 2 is discharged back into the contaminated grey water tank 3 through conduit 31. When the level in tank 3 is low as detected by low level switch 32, the controller 21 stops the pumping of contaminated grey water to the processing tank 1.

For some areas where there is no town water supply the purified grey water can be used for drinking and kitchen use. For such applications it may be necessary to add a precautionary device in the purified grey water line 27 to further ensure that should any living organisms such as bacteria, virus and algae slip through the system they will be killed before the water enters the purified grey water storage tank 2.

For applications where the purified grey water storage tank 2 may have to be located at ground level or where the user requires higher water pressure a pressure boosting pump 33 of any suitable design may be added to the purified grey water outlet line 28.

For mass produced commercial units, instead of using purified grey water from tank 2 it may be preferably to add a small flush water tank 34 immediately above the processing tank 1. This tank would be filled by the purified grey water pump 26 via line 35 and would preferably have a capacity approximately 10 of the processing tank capacity. When this tank is full a ball float valve 36 inside closes to prevent overflow.

For some countries where regulations require it or as a precaution against possible malfunction of the purification mechanism or to make the purified grey water potable a silver ion dosing device 37 or ultra-violet ray disinfectant device 38 may be added to the purified grey water line 27 before it discharges into tank 2. The silver ion dosing device 37 may be either a unit specially designed for the system or a commercially available unit.

It is preferably adapted for dosing silver ion to a level of 0.02 to 0.05 mg/litre or any other level necessary to kill the organisms in the water while still being safe for human consumption.

The ultra-violet disinfectant device 38 may also be either a unit specially designed for the system or a commercially available unit.

Other devices such as activated carbon or Zcolite absorption devices may also be used in lieu of the silver and ultra-violet devices.

It will thus be appreciated that this invention at least in the form of the example disclosed provides a novel and useful improvement to water supply systems. By collecting grey waste water from areas such as the kitchen, laundry, bath, shower and wash basin for purification and reuse it is envisaged that consumption of potable town water can be reduced by up to 75. Sewer effluent may also be reduced by up to 75%. The system at least in the form described provides a balanced and self contained water purification recycling system which requires no manual intervention and can operate continuously without maintenance for many months except for normal grease trap clearing. No additive of any kind needs to be provided during the life of the system. It is to be understood however that the embodiment disclosed is only the currently preferred form of this invention and a wide variety of modifications may be made to the system. For example the invention is not limited to any particular shape or capacity for the processing tank or storage tanks as these may be changed according to application.