it is an object of the present invention to provide a new and improved water supply system for aircraft of the type referred to above and which is not subject to the limitations as outlined , whereby specifically larger volume uses are envisioned , including the taking of showers or the like on board of the aircraft . the quality of the water , of course , has to meet the usual rules . in accordance with the preferred embodiment of the present invention , it is suggested to utilize a waste water tank and connect it to a device for recycling , purifying , and cleaning of waste water for that tank . that purified water is fed to a special frest water storage tank , and at least some of the on - board outlets and taps are connected to that tank such that the particular waste water passes through the water purification to be available again in any such particular tap , so that there is established a local circulation with a common branch or path portion that includes the storage tank , the waste water tanks , and on - board the purification plant . this particular tank could be separated from ordinary potable water in a still further tank . while the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention , it is believed that the invention , the objects and features of the invention , and further objects , features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which : fig1 is a somewhat schematic view of a water supply system in an aircraft ; and fig2 is a schematic view of the particular water purification portion and plant shown in fig1 . proceeding now to the detailed description of the drawings , a system is shown specifically for recirculating waste water to obtain , so to speak , a &# 34 ; usable &# 34 ; water supply , that is not necessarily used in the galley . the water supply system generally referred to here is provided in an aircraft and is to be used in the galley 1 , in lavatories and toilets , with a toilet bowl 2 , a washing basin 3 , and a tap 4 . in addition , a potable water tank 5 is provided which is connected to a potable water supply line 7 , a pump 6 , pumps drinking water from that tank 5 into the line conduit system 7 . analogously and in parallel thereto , there is a tank 8 which receives purified water . water is being pumped from tank 8 by means of a pump 9 , and into and through a conduit 10 . hence , there are three conduit systems , two supply systems 7 and 10 , and a discharge system 11 . as shown in fig2 the water for system 10 is derived from a purification plant 13 that feeds tank 8 . the sinks of the galley 1 and the toilet 2 as well as the sink of the washing basin 3 all are manifolded to a waste water line 11 that leads to a waste water tank 12 . the elements enclosed in dashed - out lines in fig2 constitute a device 13 for water purification . this water purification device 13 is connected to the tank 8 through a suction line 14 and a pump 15 as well as a pressure line 16 . the tanks 5 , 8 , and 12 connect to filling studs 17 , 18 , and 19 for connection and operation from the outside . this conduit / conveying system 14 - 15 - 16 is collectively denoted 23 in fig2 . a conduit 20 connects the waste water tank 12 with another stud 21 . the device 13 is comprised , in essence , of several stages wherein the waste water is purified in several stages accordingly . prior to takeoff of an aircraft being equipped with a system as outlined above , the potable water tank 5 as well as tank 8 are both filled with potable water . the waste water tank 12 has been discharged through the stud 21 . if desired , flushing may occur through the stud 19 . following take - off and during flight , the taps 4 ( there being only one of them shown ) are supplied with purified water through the conduit 10 under utilization of the operation of a pump 9 . analogously , potable water runs into the line 7 to the various taps in the galley 1 , drinking fountains , etc . as soon as waste water forms in the container 12 because of discharge from the various units to which the waste water tank is connected , water purification commences in and by operation of the device 13 . the resulting purified water is pumped through the system line 23 ( 14 - 15 - 16 ) as purified water into the tank 8 . here , then , that water is available through the aforementioned taps , and involving particularly outlets for washing water , water for taking a shower , etc . concerning specifically the water that is purified on board , there is an established circulation involving the tank 8 , the particular taps , the tank 12 , and the purifier 13 . water circulated here gradually increases in quantity owing to the use from the galley . this means that the water regarded in the past as waste water and which was no longer used , is now made available for certain purposes so that the overall amount of water that has to be carried along is reduced . a modification of such a device is to be seen in that device 13 operates in individual stages and is , in fact , supplemented and constructed to provide pure , potable water . this , of course , is a further advantage for reducing the overall weight such that a single tank , e . g . tank 8 , suffices . tank 5 is no longer necessary , without having to enlarge tank 81 . also , one of the conduit systems 7 and 10 is now superfluous . there is only a single quality of water . a particular advantage of the device as described is to be seen in that prior to take - off the amount of water that is to be loaded is , in fact , relatively small . that , in turn , means that instead of water one can add passengers . alternatively , it may now be possible for passengers to take a shower , which in the past simply was a prohibitive waste of water . fig2 illustrates in greater detail the purification device 13 as it is connected to the waste water tank 12 , the connection involving primarily a conduit 22 . there are additional conduits 23 and 24 for and providing connection to the tank 8 . through additional conduits 23 and 24 , the device 13 is connected to the storage tank 8 as well as to an ozone generator which is not whown in detail . device 13 is constructed in that water entering through conduit 22 passes in sequence the following units and purification stages . first of all , there is a mechanical filter 25 to remove relatively coarse particles , particularly to keep these particles from the pump 26 . downstream from the pump 26 is provided a carbon filter 27 , including a bed of active carbon , and downstream from that is provided an ozone stage 28 followed by an osmotic stage 29 and a disinfecting stage 30 . fig2 shows , moreover , that ozone is also fed into the waste water tank 12 directly through the conduit 24 . in other words , the waste water tank 12 is so to speak a first stage so that , in fact , 28 is a second stage for ozone adding . that kind of function and the operation of the respective units may be modified , as far as the water treatment is concerned , because there may be conditions which require such modification . nevertheless , the various effects produced by the various units should all be provided for in one form or another and are , in fact , known from water purification . nevertheless , they should be summarized here as follows : the mechanical filter 25 removes primarily suspension , dust particles and the like . active carbon is used in water purificaiton for a variety of reasons . for example , certain contaminants and materials solved in water are being bonded in some form or another to this carbon . in addition , carbon adsorbs large amounts of contaminants such as insecticides , water tension reducing materials , and so forth . also carbon favors the decompositioning of certain contaminants by means of bacteria and acts in some instances as a catalyst , for example , in the case of chlorine compounds , so that the respective contaminants are removed from the water on that basis . the ozone treatment is primarily biological in nature in that many microorganisms , such as bacteria and virus , are eliminated by the ozone . also , certain flavoring materials , incense or the like , as well as other organic materials such as phenol are removed or decomposed by the ozone . also , basic elements like iron , manganese , and sulfur are removed by the treatment with ozone , while , on the other hand , in a quite desirable to increase the oxygen concentration in the water . the osmosis stage 29 uses particularly the so - called inverse osmosis . here the water is forced against the osmotic pressure through the molecular texture of a semipermeable membrane . owing to this particular effect only water can pass through that membrane so that indeed pure water is collected downstream from that membrane . in the case the ozone supply is insufficient , algae or other deposits may form in the respective conduits . in order to avoid this undesirable effect , disinfection may be used to add a very small amount of chlorine to the water . another feature is to include irradiating the water with ultraviolet light or even evaporation with subsequent condensation . unfortunately the irradiation with ultraviolet light is a very expensive one in terms of equipment and the evaporation and recondensation requires high amounts of energy are therefore not desirable . however , the invention is not limited to configurations of the type mentioned , particularly as far as the accumulation of various method steps for water purification are concerned , but additional steps , including any other conceivable water treatment that is practical on board , can be used . thus , the invention is not limited to the embodiments described above , but all changes and modifications thereof , not constituting departures from the spirit and scope of the invention are intended to be included .