Patent Publication Number: US-2015068625-A1

Title: Readily cleanable dual purpose water storage system and method

Description:
CROSS REFERENCE 
     This application is a continuation-in-part of application Ser. No. 13/383,013 filed on 9 Jan. 2012. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a readily cleanable water storage system and particularly an improved water storage tank for this system and method of regular cleaning thereof by which high level of cleanliness of water can be maintained with considerable ease in a cost effective manner. This invention further relates to a dual purpose water tank wherein the water content of the lower portion of the tank is kept constantly reserved for use in sprinklers for fire fighting operations and the water content of the upper portion is used for supply of potable grade water to consumers. 
     BACKGROUND OF THE INVENTION 
     Storage of water is essential before distribution to the consumer through a pipeline. To this end, water tanks of various sizes and kinds are used. Tanks made out of metal, brick and mortar are now giving way to those of plastic or synthetic materials due to various reasons like cost effectiveness, ease of installation and maintenance, non-susceptibility to leakages, etc. Wooden water tanks are also in use in certain regions of the world. 
     However, one cause of concern in all kinds of water tanks currently available is its poor level of cleanliness and that of its contents. Water entering the tank from the city&#39;s water source invariably contains some foreign matters. Over a period of time the foreign matters in the form of suspended impurities settles to the bottom of the tank and requires periodic cleaning. It is not unusual for a tank to accumulate anywhere up to an inch or so of muddy sediments over a period of time, a residue that pose severe health hazard for the consumers. 
     Water tanks have not changed much during the past hundred years or so. Some of the techniques used in their construction have been improved resulting in shorter manufacturing and installation time, but the overall principle of water tanks remains unchanged. 
     Conventional water tanks in use are either rectangular or cylindrical in shape in general and the outlet for supply of water to consumers is at a point on its sidewall slightly above its bottom. This point is so chosen so as to allow all the suspended contaminants, dirt and muddy substances in the water to settle down on the bottom surface that do not pass into the supply outlet located above the deposited sediments. These impurities some of which hang in the water content keep on depositing on the floor of the tank turning into a sludge over a period of time, which require to be thoroughly scrubbed in order to dislodge it effectively. This cleaning is an elaborate process requiring some preparation and stoppage of water supply to the consumers for a considerable period. Considerable time and effort is spent in scrubbing out those sticky deposited materials. Since the outlet from the tank is a bit above the bottom, all the scrubbed material along with water remaining below this outlet requires to be lifted and thrown out with the help of buckets, mugs, or by other means. This is followed by sponge drying and disinfecting of the bottom surface and inside walls of the tank. All this is a lengthy and cumbersome process and still does not assure a constantly high level of cleanliness. Further, it may leave scratches on the inside surfaces of the tank that may corrode the tank progressively. Also, the lengthiness of the process tends to reduce its frequency, thereby compelling the consumers to consume harmful contaminated water indefinitely. 
     During the daily chore of filling of tank, the falling mass of water inside the tank dislodges part of the said layer of sediments from the floor and this material rises above to dance and revolve with the agitated mass of water. This continues till the filling of water progresses. It also settles partly on the side walls of the tank thereby dirtying them as well. Most of these foreign matters remain in a suspended state owing to buoyancy for considerable time and continue to pass on to the supply route away from the tank. Till such time the users are forced to continue consuming such contaminated water for various uses in the bath, kitchen, washing, etc., and for drinking. Also, a part of the impurities and dirt, which is soluble, gets dissolved during the swirling agitation of water and may not be detected visually. All this make the supplied water a carrier of impurities which gets thicker and denser with every passing day and good part of it is also deposited on the inside wall of the water supply line thereby reducing the flow rate with passage of time. This is a compulsion everyone lives with which is not realized because the dirty scene of action happens to be away in the closed tank at the top of the building and one cannot make out dirtiness by simply looking at the water at the receiving end. 
     It is true that some people keep water filters at the users&#39; end in order to get clean potable water. But there are again several factors that decide the quality of water one gets from it. These may be like quality assurance associated with that filter, whether that filter is properly maintained or not with timely replacement of cartridges, candles, etc. Again, water filters are primarily used for the purpose of drinking water only. Bulk of the water supply is directly used during bathing, brushing teeth, washing mouth after meals, food preparation, etc. Therefore, one still remains vulnerable to the dirty water coming from the supply route from that overhead tank. 
     So, a vast majority of human population, with the exception of those people who live in remote areas where such tanks are not used for storage of potable water, has no way but to consume such contaminated water. 
     Potable water is a basic necessity of life and deserves the same level of care, cleanliness and respect as any other food item. Every utensil handling food items is given a complete washing in dishwasher or manually and in the same fashion the water storage tank should be maintained with complete renewal of stored water regularly. This does not happen in the conventional tank and total cleanliness is erroneously presumed. With every filling of the tank, certain amount of stale water remains in the bottom along with those muddy sediments. It is happening despite countless people being involved in the business of storage water tank right from design and manufacture, distribution and dealers&#39; network to plumbing and installation and finally to end users. Also, there is a vast network of tank maintenance and cleaning companies and establishments which specialize in the expertise of tank cleaning. These people follow elaborate processes for the job and charge substantially. In spite of the involvement of technical people, the scenario remains the same. 
     So, an urgent solution was needed so that the regular renewal of the water content in the tank is possible in order to ensure a high cleanliness level of water within the tank in a cost effective, convenient and time-saving manner. 
     The objective of this invention is to present a solution in the shape of an improved design of a water tank and a method of cleaning the same which ensures a comparatively much higher level of cleanliness of water for the consumers. It ensures complete renewal of the water content of the tank in an extremely convenient method which can be carried out regularly and swiftly with utmost ease in a cost effective manner. 
     Another objective of this invention is to provide a dual purpose water tank wherein the water content of the lower portion of the tank is kept constantly reserved for non-potable use in sprinklers for fire fighting operations and the water content of the upper portion is used for supply of potable grade water to consumers with rest of water content getting constantly renewed. 
     SUMMARY OF THE INVENTION 
     The present invention mainly lies in the shape of a water tank which appears more or less similar to conventional water tank from the outside except for the bottom side. The tank may be of cylindrical, rectangular or any other shape and may be made of any material. The major difference lies in the inside bottom of the proposed tank which is inclined with a continuous effective slope so that all the water inside rushes down the slope of the inclined or conical bottom. It has an outlet for complete drain out of water from the said inclined or conical bottom of the tank. This outlet, which may be located anywhere along the periphery at the sloping end of the floor or at the convergence of the cone for a tank with conical bottom, is meant for draining out the water inside the tank completely whenever desired. This draining outlet may be extended through extra pipeline to a convenient place and a stop cock provided at that point to discontinue the discharge of water from drainage outlet. Alternatively, a drainage outlet is provided with electronically operated stopping means that can be remotely controlled for convenience of the cleaning operation. When the said draining outlet is opened, the water from inside the tank starts flowing out and as the water level approaches the bottom of the tank, all of it rushes towards the said exit at the lowest point as no water can remain on the slant surface of the bottom. The draining outlet at the lowest point of slope should not have any protrusions or edges towards the inside, which may obstruct exit of the sediments, impurities, etc. The mouth of the draining outlet should have a smooth converging easy curvature for uninterrupted flow of drainage water therethrough. Bend sections in extended pipeline may be kept at a minimum. 
     Eventually the tank empties by itself without any special effort made for the purpose in contrast with the conventional tank which requires cleaning personnel to go physically inside and lift water from the bottom with considerable effort. All the sediments and other foreign matter also rush out through the said draining outlet without any external action involved. After the tank empties itself on its own, the water inlet for filling the tank is opened. Water starts falling on the said inclined bottom of the tank which further cleans the bottom and flushes further dirt, if any, towards the said draining outlet and is drained out. Some time is allowed for this process to continue before the said draining outlet is closed and water filling in the tank starts for storage. The outlet for supply to consumers is fixed at a point higher than the said bottom of tank described above so that only clean water goes into the supply line. Therefore, the consumers do not get any contaminated water as in the case of conventional tanks wherein all the sediments and impurities continue to accumulate progressively at the bottom with passage of time that contaminates the water in the supply line as discussed above. 
     There may appear a wastage of a small amount of water mass which lies between the said supply outlet and the draining outlet in the process of this complete renewal of water. This is only notional, because this water can be directed towards some other utilities where potable grade water is not required, like floor and other type of cleanings, gardening, watering of plants and trees, washing of vehicles, etc. 
     In one embodiment of the present invention it provides a readily cleanable water storage system with a water tank having an inclined or conical bottom with a continuous and effective slope which automatically rushes all the water content towards the draining outlet located at the end of the said slope or at the convergence of the cone of the conical bottom. The supply outlet for consumers is located at a point well above the draining outlet. 
     The said draining outlet is optionally extended to a place convenient for the user to operate and a stopping mechanism provided at that point so that the operator can close or open the said draining outlet from that point whenever required. Alternatively, an electronically controlled stopping means can be provided closer to the water tank, with a remote control switch available with the operator for an easy operation especially in case of taller buildings where extending the draining outlet by extra pipeline may not be cost effective or remain trouble-free. 
     The tank may be emptied regularly/daily or preferably before every filling by opening the said draining outlet, some fresh water allowed through the inlet and allowed to drain out and then fresh water stored by closing the draining outlet. 
     The small amount of tank water which comes out of the draining outlet, during periodic renewal of water in the tank, may be optionally directed towards non potable usage thereby saving water from wastage, even during the periodic renewal of water in the tank. 
     The present invention in one embodiment thus provides a readily cleanable water storage system comprising: an overhead water tank for storing potable and other kind of water, wherein said water tank comprises: a floor, at least one inlet for letting water to be filled into said tank, a draining outlet with a stop cock fitted thereto, an overflow outlet, and a consumer supply outlet through which water is supplied to consumers and a pump for pumping water from a water supply source at ground level to the overhead tank for storage of water before supply to consumers, characterized in that the floor of the tank is inclined at a pre-determined continuous and effective slope either towards another point on the periphery to form an inclined floor or from all sides to form a conical bottom and the draining outlet is located at the periphery of the inclined floor at the sloping end or at the convergence of the cone formed by the conical bottom, as the case may be, in order to completely discharge the water stored in the tank when the draining outlet is opened. 
     The draining outlet may be optionally extended to a place convenient for the user to operate and a stopping mechanism provided at that point so that the operator can dose or open said draining outlet from that point. A remote electronically controlled stopping mechanism may be provided closer to the water tank, with the remote control switch available with the operator for easy operation, particularly in taller buildings. The stop cock or the remote control switch is preferably accessible and capable of being operated from a lower floor of the building such as ground floor by virtue of being fitted in an extended draining outlet pipe closer to the level from which it is desired to be operated. The stop cock or remote control switch for draining outlet is most preferably located close to the pump room housing the pump which supplies water to said tank. The supply outlet for consumers is located at the side wall at a point above the starting end of sloping floor of the tank and the water inlet is located at a point to discharge the water near the starting end of the sloping floor of the tank. 
     The bottom of the water tank in one embodiment may be inclined from all the sides to make a cone and the supply outlet can be located at the side wall of the tank preferably above the conical bottom of the tank. A draining outlet pipe may be located at the point of convergence of the cone with the draining outlet pipe extending to a convenient place at a lower floor preferably ground floor for cleaning of the water tank through a stop cock. The water inlet(s) is/are located so as to discharge the inlet water on the inclined surface(s) of the conical bottom of the tank. 
     The present invention in another embodiment provides a method of maintaining cleanliness of water in the overhead tank of a water storage system wherein the overhead tank has a sloping floor or a conical bottom with a drainage outlet at the periphery of the sloping floor at the sloping end or at the convergence of the cone forming the conical bottom comprising the steps of (a) regularly draining out the water held in the tank by opening the stop cock of the draining outlet to completely empty the tank; (b) opening the inlet of tank to dislodge any sediment or deposit still adhering to the floor or bottom of the tank by letting in the jet of one or more water inlet(s) from the water supply line and allowing it to fall on sloping floor or conical bottom of the tank while keeping the drainage outlet still open and (c) refilling the tank with fresh water from the supply inlet after dosing the drainage outlet after some time. 
     Water from the inlet falls directly on the impurities if any collected at the bottom of the water tank such that those are easily dislodged. Occasionally, a sponge or cloth like cleaner or brush attached to a long handle is used to rub out and clean the bottom and walls of the tank, followed by water being allowed to flow in the said tank for a few minutes through draining outlet for final cleaning before closing the stop cock of the said draining outlet to hold fresh clean water in the tank. The tank may have a conical funnel shaped bottom and the discharge from the inlet is directed to different points on the inclined surfaces of the conical bottom of the tank by manipulating the inlets for pumped water in the tank. 
     The invention in one embodiment provides for separate outlet for taking out potable water for consumption from an upper level of the stored water and also a sensor to actuate the pump for pumping fresh water after fall in water level to a predetermined level in the water tank, while water from the bottom outlet of inclined floor is diverted for non-potable purposes. 
     The invention in another embodiment provides a second conical or inclined floor that separates the water tank into two compartments such that the water from the lower compartment is used for non-potable purposes and the water from the upper compartment is used for potable purposes. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
       This invention is described below with the help of accompanying drawings in which:— 
         FIG. 1  illustrates a conventional common rooftop water tank. 
         FIG. 1A  illustrates another conventional water tank with a flat bottom having a sensor mechanism and the consumer outlet being located at a level around the sensor mechanism. 
         FIG. 2  illustrates a water tank according to one embodiment of the invention having an inclined bottom. 
         FIG. 2A  illustrates a water tank according to one embodiment of the invention having an inclined bottom, a sensor mechanism for refilling the tank, and a consumer outlet being located at a level around the sensor mechanism. 
         FIG. 2B  illustrates a water tank according to one embodiment of the invention having a second inclined floor, located above a first inclined floor, the second inclined floor being provided at about the midway of the vertical height of the tank with a second draining outlet at the sloping end of the second inclined floor, for draining water below the second inclined floor down towards first inclined floor. 
         FIG. 2C  illustrates a water tank according to one embodiment of the invention having a second inclined floor, located above a first inclined floor, the second inclined floor being provided at about the midway of the vertical height of the tank with a second draining outlet at the sloping end of the second inclined floor for draining water below the second inclined floor, and a floating ball stopper to maintain unidirectional downward flow of water, and prevent mixing of waters of the two compartments created by the second inclined floor. 
         FIG. 3  illustrates a water tank according to another embodiment of the invention with a draining facility which is more convenient to operate. 
         FIG. 4  illustrates a water tank according to yet another embodiment of the invention having a conical bottom with a draining facility which is more convenient to operate. 
         FIG. 4A  illustrates a water tank according to one embodiment of the invention having a conical bottom, a sensor mechanism for refilling the tank, and a consumer outlet being located at a level around the sensor mechanism. 
         FIG. 4B  illustrates a water tank according to one embodiment of the invention having a second conical floor, located above a first conical floor at the bottom of the tank, the second conical floor being provided at about the midway of the vertical height of the tank with a second draining outlet at the convergence of the second conical floor, for draining water below the second conical floor. 
         FIG. 4C  illustrates a water tank according to one embodiment of the invention having a second conical floor, located above a first conical floor at the bottom of the tank, the second conical floor being provided at about the midway of the vertical height of the tank with a second draining outlet at the convergence of the second conical floor for draining water below the second conical floor, and a floating ball stopper to maintain unidirectional flow of water and prevent mixing of waters of the two compartments created by the second conical floor. 
         FIG. 5  illustrates a water tank according to still another embodiment of the invention, wherein the water inlet(s) is/are located so as to discharge the inlet water at different points on the inclined surface(s) of the conical bottom of the tank. 
         FIG. 6  illustrates a water tank according to still another embodiment of the invention, wherein the water inlet(s) is/are located so as to discharge the inlet water at different points on the inclined surface of the bottom of a rectangular or cylindrical tank. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a conventional water tank  10  erected on the base  16  commonly in use today wherein water is filled through the inlet pipe  11  into the tank and the surplus water during the filling process exits through overflow pipe  12 . The outlet  14  is for consumer supply through which water is sent to the consumers. The sediments and foreign matter  15  that have deposited at the floor of the tank over a period of time can be seen. 
     As shown in  FIG. 1A , the conventional water tank may additionally have a sensor mechanism  13  which activates the water filling mechanism (pump) whenever the water level falls down to a predetermined level for injecting fresh water. The consumer supply outlet  14  are sometimes provided to be near a level at which the sensor  13  operates to inject fresh water. 
     It can be seen that the scenario here promotes accumulation of dirt, impurities, sediments etc. in the water content because nearly half of the water content is always retained as stale water every time the tank is topped up by the water filling mechanism. During such operation, fresh water falls down on the stale water content, and all the impurities and dirt get agitated and start moving around and dancing along with the swirling water content. A vertical movement of water, dirt, impurities, germs, bacteria etc. may happen due to other factors too like temperature difference, heavier and lighter contaminants etc. Consumers receive their share of such contaminated waters along with these impurities, as they open their taps. This is repeated everyday as the dirt get multiplied progressively because a water reserve of somewhat like half of the tank&#39;s capacity is required to be maintained always and no complete evacuation can take place in this case. 
       FIG. 2  shows a preferred embodiment of the present invention in which the inclined floor  21  of the water tank  20  is shown and a draining outlet  22  with a stop cock ( 27 ) is located at a point at the end of the slope of the said inclined floor  21 . The inlet  24  is meant for water to be filled into the tank by a pump or other means with overflow outlet  23 . The consumer supply outlet  25  supplies water to its consumers. The consumer supply outlet  25  is located at a level just above the starting end of the inclined floor  21 . 
     In another preferred embodiment of the present invention, as shown in  FIG. 2A , the water tank, in addition to the one shown in  FIG. 2  and discussed in the preceding paragraph, has a sensor mechanism  29  at about the midway of the vertical height of the water tank, while the consumer supply outlet  25  is located near a level which is around the level of the sensor mechanism  29  which activate the pump to inject fresh water as soon as the level of water inside the tank falls below a pre-determined level which is level of reserve to be maintained. The draining outlet  22  is provided at the lowest point of the slope which may be extended and connected to a network of secondary uses for non-potable purposes like toilet cisterns, washing machines, floors and driveway cleanings, gardening etc. The sensor mechanism  29  is there to activate at the right moment to replenish whatever water mass finds way out of the draining outlet  22  and maintaining the reserve as per the requirement. Consumers continue to receive potable grade water through the consumer outlet near the mid-height of the tank. The water inlet  24  may be constructed with multiple openings or pores so as to discharge jets of inlet water at different points of the inclined floor  21  of the tank  20  thereby helping to dislodge the impurities adhering to the bottom of the tank more reliably after switching off the sensor in case no reserve is required, thereby completely evacuating the water tank for cleaning purposes. A substantial improvement in level of cleanliness is achieved from this arrangement in comparison with that of the conventional tank of  FIG. 1  and  FIG. 1A  because dirt and impurities do not get an opportunity to accumulate but are let out through draining outlet  22  of the inclined floor progressively. 
     In another preferred embodiment of the present invention, as shown in  FIG. 2B , the water tank, in addition to the first inclined floor at the bottom of the tank shown in  FIG. 2A  and discussed in the preceding paragraph, is provided with a second inclined floor  32  somewhere near the mid way of the vertical height of the water tank  20  but below the level of the sensor mechanism  29 , which divides the tank broadly into two compartments, namely, upper compartment  33  and lower compartment  35 , one above the other, but the second inclined floor  32  is located above the first inclined floor  21 . The consumer supply outlet  25  is located at a level above the starting end of the second inclined floor  32 . A second draining outlet  34 , located at the sloping end of the second inclined floor  32  is capable of draining out completely the water content in the upper compartment  33  down to the lower compartment  35  so created. Thus, the vertical movement of water and impurities etc. is mostly curtailed to a minimum which can happen only through the second draining outlet  34 , which is an opening wide enough to simultaneously fill the lower compartment to constantly maintain the reserve level therein. This second draining outlet  34  may be just a simple opening, as shown in  FIG. 2B , or a check valve may be provided to allow only unidirectional downward flow. Alternatively, a U or other shaped tube may be used to ensure unidirectional movement of water from upper compartment  33  to the lower compartment  35  of the tank. This arrangement ensures better cleanliness environment in the upper compartment  33  which houses the potable grade water for supply to consumers. The water tank may also have a siphoning facility  36  to supply water to consumers. The water inlet  24  may be constructed with multiple openings or pores so as to discharge jets of inlet water at different points on the second inclined floor  32  of the tank  20 , thereby helping to dislodge impurities adhering at the second inclined floor  32  and transferring them to the lower compartment  35 . Thus, potable grade clean water from the upper compartment  33  is provided to the consumers via the consumer supply outlet  25 , while the water from the lower compartment  35 , which comes out from the draining outlet  22 , may be extended and connected to a network of secondary uses like toilet cisterns, washing machines, floors and driveway cleanings, gardening etc. The sensor mechanism  29  is there to activate the pump at the right moment to replenish whatever water level falls to a pre-determined level at the upper compartment  33  to maintain supply of potable grade water to consumers. 
     In another preferred embodiment of the present invention, as shown in  FIG. 2C , the water tank, in addition to the one shown in  FIG. 2B  and discussed in the preceding paragraph, additionally has a floating ball stopper  42  to stop water passing through second draining outlet  34 . The lower compartment  35  below the second inclined floor  32  holds the water kept in reserve for fire fighting eventualities, should the occasion arise. This reserve has always to be maintained at full and gets water from the second draining outlet  34 . The upper compartment  33  located above the second inclined floor  32 , which receives fresh water through inlet  24 , serves to supply fresh potable grade water to consumers and gets maintained regularly through renewal of its water content in the manner as discussed above. In this embodiment, the draining outlet  22  at the bottom of the lower compartment  35 , may, like in previous embodiment, preferably, be connected to a network of secondary uses like toilet cisterns, floor cleaning outlets, gardening terminals, cleaning of driveway etc. and may be, for cloth washing terminals as well. In the process, the inclined floor  21  is getting cleared of impurities and sediments substantially, as water in the surrounding spaces finds way out through the draining outlet  22 . The space getting so vacated in the lower compartment  35  gets automatically filled simultaneously from the upper compartment  33  through second draining outlet  34 , just to be stopped by the stopping mechanism  42  when the lower compartment  35  is filled to its capacity. In the process the second inclined floor  32  too gets cleared of impurities and sediments to a fairly good extent. 
     In  FIG. 3 , the water tank  20  of the present invention is shown on the top of a building  30 . Here its draining outlet pipe has been extended and brought along the height of the building of several floors down to the ground level. Its stop cock  27  is accessible from the ground level and can be operated from there itself and is close to pump room  31  housing the pump which supplies water to the tank  20 . 
       FIG. 4  shows another preferred embodiment of the present invention in which the water tank  20  is filled with water up to level  26 . The water inlet is depicted by  24 , the overflow outlet by  23 , and the supply outlet for consumers by  25 . Here the bottom of the tank is inclined from all the sides somewhat into a funnel shape converging at  22  the converging point of the cone, thereby providing a conical floor  48 , where draining outlet pipe  30  is attached. Said outlet  30  extends to a convenient place from where the draining process can be carried out comfortably at regular intervals through the stop cock  27 . 
     In another preferred embodiment of the present invention, as shown in  FIG. 4A , the water tank, in addition to the one shown in  FIG. 4  and discussed in the preceding paragraph, has a sensor mechanism  29  near the midlevel of the water tank, while the consumer supply outlet  25  is located near a level which is around the level of the sensor mechanism  29  which activates the pump to inject fresh water as soon as the level of water inside the tank falls below a pre-determined level. The draining outlet  22  is provided at the convergence of the conical floor  48  which may be extended and connected to a network of secondary uses like toilet cisterns, washing machines, floors and driveway cleanings, gardening etc. The sensor mechanism  29  is there to activate at the right moment to replenish whatever water mass finds way out of the draining outlet  22  and maintaining the reserve as per the requirement. Consumers continue to receive potable grade water through the consumer outlet near the midlevel of the tank. The water inlet  24  may be constructed with multiple openings or pores so as to discharge jets of inlet water at different points on the conical floor  48  of the tank occasionally after switching off the sensor mechanism  29  for complete evacuation of water. thereby helping to dislodge the impurities adhering to the bottom of the tank more reliably. A substantial improvement in level of cleanliness is achieved from this arrangement in comparison with that of the conventional tank of  FIG. 1  because dirt and impurities do not get an opportunity to accumulate but are let out through draining outlet  22  of the conical floor  48  progressively. 
     In another preferred embodiment of the present invention, as shown in  FIG. 4B , the water tank, in addition to the first conical floor  48  located at the bottom of the tank, as shown in  FIG. 4A  and discussed in the preceding paragraph, the tank  20  is provided with a second conical floor  48 ′ in the mid way of the vertical height of the water tank but below the level of the sensor mechanism  29 . The second conical floor  48 ′ is located above the first conical floor  48  that divides the tank broadly into two compartments, namely, upper compartment  33  and lower compartment  35 , one above the other. The consumer supply outlet  25  is located at a level above the starting end of the second conical floor  48 ′. A second draining outlet  50 , which is located at the convergence of the second conical floor  48 ′ is capable of draining out completely the water content from the upper compartment  33  down to the lower compartment  35  so created. Thus, the upward movement of water and impurities etc. is mostly curtailed to a minimum which can happen only through the second draining outlet  50 , which is a small hole. This second draining outlet  50  may be just a simple opening, as shown in  FIG. 4B , or a check valve to allow only unidirectional downward flow. Alternatively, a U-shaped tube may be used to ensure movement of the contents of the upper compartment  33  to the lower compartment  35  and to prevent the reverse flow. This arrangement discourages vertical movement of water and impurities in the upward direction and ensures better cleanliness environment in the upper compartment which holds the potable grade water for supply to consumers. The water tank may also have an alternative siphoning facility  36  to supply water to consumers. The water inlet  24  may be constructed with multiple openings or pores so as to discharge jets of inlet water at different points on the second conical floor  48 ′ of the tank  20 , occasionally after switching off the sensor mechanism  29  for complete evacuation of water from upper compartment  35 , thereby helping to dislodge impurities adhering to the second inclined floor  48 ′ more reliably and transferring them to the lower compartment  35 . Thus, potable grade clean water from the upper compartment  33  is provided to the consumers via the consumer supply outlet  25 , while the water from the lower compartment  35 , which comes out from the draining outlet  22 , may be extended and connected to a network of secondary uses like toilet cisterns, washing machines, floors and driveway cleanings, gardening etc. The sensor mechanism  29  is there to activate at the right moment to replenish whatever water mass finds way out of the draining outlet  22  and maintaining the reserve as per the requirement. 
     In another preferred embodiment of the present invention, as shown in  FIG. 4C , the water tank, in addition to the one shown in  FIG. 4B  and discussed in the preceding paragraph, additionally is provided with a floating ball stopper  42  to stop water passing through second draining outlet  50  when the lower compartment  35  is full. The lower compartment  35  below the second conical floor  48 ′ holds the water kept in reserve for fire fighting eventualities, should the occasion arise. This reserve has always to be maintained at full and gets water from the second draining outlet  50 . The upper compartment  33  located above the second conical floor  48 ′, which receives fresh water through inlet  24 , serves to supply fresh potable grade water to consumers continuously through renewal of its water content in the same manner as discussed above. In this embodiment, the draining outlet  22  at the bottom of the lower compartment  35 , may, like in previous embodiment, preferably, be connected to a network of secondary uses like toilet cisterns, floor cleaning outlets, gardening terminals, cleaning of driveway etc. and may be, for cloth washing terminals as well. In the process, the first conical floor  48  is getting cleared of impurities and sediments substantially, as water in the surrounding spaces finds way out through the draining outlet  22 . The space getting so vacated in the lower compartment  35  gets automatically filled from the upper compartment  33  through second draining outlet  50 , just to be stopped by the stopping mechanism  42  when the lower compartment  35  is filled to its capacity. In the process the second conical floor  48 ′ too gets cleared of impurities and sediments to a fairly good extent. Near total cleaning of the sloping floor is achieved regularly or whenever desired through complete evacuation of the upper compartment through its draining outlet  50  and allowing falling water through inlet  24  to impact on the second conical floor  48 ′ in the upper compartment  33 . A suitably long handle brush may also be used to further clean the conical floor in the upper compartment. In one embodiment, the upper floor may be a conical floor while the lower floor may be an inclined floor and vice versa. 
       FIG. 5  shows a water tank according to still another embodiment of the invention, wherein the water inlet(s) is/are located so as to discharge the inlet water jets at different points on the inclined surface(s) of the conical bottom of the tank. 
       FIG. 6  shows a water tank according to still another embodiment of the invention, wherein the water inlet(s) is/are located so as to discharge the inlet water jets at different points on the inclined surface of the bottom of a rectangular or cylindrical tank. 
     The funnel shape of the tank helps to draw the water with any suspended material inside the tank towards the convergence point  22  when the draining outlet  30  is opened for draining out the contents of the tank. Flow convergence coupled with gravity plays a prominent role relative to a situation where the draining outlet is situated on the periphery or elsewhere. When the tank is filled, all the dirt and foreign matter are directed towards the outlet  22 . This helps in draining out the contaminated water and clean the tank. 
     It can be seen that as the conventional water tank  10  of  FIG. 1  and  FIG. 1A  is filled everyday, the sediments or foreign matter start depositing from day one. It adds up everyday and over a period of time forms a sludge like layer  15  at the floor of the tank. The cleaning process of such water tank being lengthy, time taking, labour intensive one, requires some preparation and advance planning to carry out the same and the supply of water from this tank requires to be discontinued during the process. The cleaning process in such conventional tank is carried out at fairly longer intervals because the aforesaid difficulties tend to delay the job. For this long period, the users consume everyday, progressively more dirtier water. 
     In sharp contrast, the proposed water tank  20  provides comparatively much higher level of cleanliness in water which is almost like the fresh water that is filed into the tank everyday due to the fact that the foreign matter in water does not get enough time to deposit at the inclined bottom  21  due to the slope and is regularly drained out through the outlet  22  situated at its lowest point at the end of the slope. This draining out of all contaminated water can be carried out as frequently as desired because this requires only opening and closing of a tap, which even a child can do. In order to make the job still more convenient, the said draining outlet can be extended to a lower floor of convenience closer to the pump, even to the ground level as in  FIG. 3  and the stop cock  27  fitted there to enable cleaning of the overhead tank before pumping fresh water into the tank. 
     A typical action for maintenance of this proposed water tank may be to first drain out the contents of the tank by opening the stop cock  27 . When it is fully empty the pump is started. Water starts falling on the floor of the tank through the inlet  24  which dislodges most of the sediments and deposits on the sloping floor of the bottom of the tank that drains out through the outlet  22  or  30 , as the case may be. Occasionally, at long intervals, a sponge or cloth like cleaner or brush attached to a long handle can be used to rub out clean the bottom and walls of the tank, if so desired, followed by letting inlet water to flow in for a few minutes to clear these materials and finally the stop cock of the said draining outlet is closed. The tank is then ready to fill with fresh clean water. 
     In the embodiment of the invention illustrated in  FIG. 5 , the water inlet(s) is/are so located as to discharge the inlet water on the inclined surface(s) of the conical bottom of the tank. 
     It is also observed that a slope of around 15 to 25 degrees to the horizontal of the inclined bottom appears fairy workable for the impurities like a mixture of common soil and sand to move towards the draining outlet if the tank is made of metal. A larger angle will obviously result in a more favourable flow pattern. The material and surface qualities and conditions of the inclined bottom of the tank and the nature of impurities or sediments are also factors that determine the extent of slope for the inclined bottom to make the operation smooth. 
     This process of complete renewal of water is carried out regularly. As a result, the level of dirt in water is not allowed to rise by accumulation over a period of time. This is in contrast with the current scenario where in a conventional water tank the level of dirt keeps on rising everyday progressively till it is cleaned after a long interval. The level of cleanliness in the invented water tank always remains very high and it very rarely requires a thorough cleaning. 
     The present invention helps to realize the following advantages:
         i) The level of dirtiness in the water tank according to the invention remains always at a very low level as compared to a conventional tank, which requires an extensive and expensive cleaning.   ii) The draining out of the contents of the water tank of the present invention is extremely simple and can be carried out regularly and as frequently as desired.   iii) The regular draining out of the content of the water tank of the present invention does not require additional manpower nor any special equipments or arrangement for the purpose and without any long disruption of water supply as in the case of conventional water tank cleaning.   iv) Storage of potable grade and non potable grade waters along with their outlets getting separated in the tank itself makes it possible that their transit and entry into kitchens, wash basins etc. are too separated from that of toilet cisterns etc., linked to W.C. ultimately. This eliminates any possibility of hygiene and sanitation problems arising out of present methods of single transit and entry of water for all those utilities.   v) The cost, time and labour involved in maintenance and cleaning the proposed tank is comparatively very low.   vi) The resultant health and hygiene benefits for consumers are enormous.