AU2003212066B2 - Self-Cleaning Water Tank - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Booth Holdings (QId) Pty Ltd Actual Inventor: Graham Roy Booth Address for Service: CULLEN CO.

Patent Trade Mark Attorneys 239 George Street Brisbane, Qld. 4000 Australia.

Invention Title: Self-Cleaning Water Tank Details of Associated Provisional Application: PS3372 3 July 2002 The following statement is a full description of this invention, including the best method of performing it known to us: SELF-CLEANING WATER TANK This invention relates to water storage and is particularly concerned with self-cleaning water storage tanks.

BACKGROUND OF THE INVENTION Rainwater collection and storage is becoming a major priority in urban development as water resources are becoming scarce and depleted with ever increasing use by an increasing population. Pressure is being applied to developers and individual household owners to maximise the conservation of mains water supply by supplementing, or even replacing it, with their own water collection systems. There is, however, a reluctance by individuals to collect and store rainwater falling on their roof because of the contamination which can occur in the water on storage. Typically, the water collected from the roof of a building is passed into a storage tank and the entrained contaminants settle to the bottom of the tank. It is from the bottom region that the water is usually drawn for use with the result that the contaminants are the first to be ingested.

OBJECT OF THE INVENTION It is therefore an object of the present invention to provide a water storage tank from which such contaminants can be effectively removed.

SUMMARY OF THE INVENTION According to the present invention there is provided a selfcleaning water storage tank, said tank including: a rainwater inlet; a contaminated water outlet; and a potable water outlet, wherein the rainwater inlet is positioned at a lower region of the tank and expels water in a pathway which follows a perimeter of the lower region so as to produce a vortex within the tank, and wherein the contaminated water outlet is positioned at a lower central region of the tank so that contaminated water that has accumulated at the lower central region can be removed from the tank therethrough.

DETAILED DESCRIPTION OF THE INVENTION The formation of a vortex within the tank results in a concentration of the entrained particulate contaminants by that vortex due to centrifugal and rotational forces bringing the heavier contaminants together by known physical principals. Such vortex formation is also a function of gravitational forces and the direction of spin of the planet. Therefore, to ensure that turbulence does not occur in water which would result in the contaminants being dispersed throughout the body of stored water, it is necessary that the rainwater inlet direct the rainwater in an anti-clockwise direction in storage tanks located in the Southern Hemisphere of the planet, and in a clockwise direction in storage tanks located in the Northern Hemisphere. That is, alignment of the rainwater inlet is with the natural direction which water flows in the particular Hemisphere as is, for instance, observed when water flows out a plug-hole in a wash basin.

The water storage tank can be any conventional tank used for storing water. However, in order to maximise the self-cleaning attributes it is preferred if the tank has a cylindrical sidewall. This ensures minimal turbulence and maximises the formation of a uniform vortex. Preferably, the tank has a cylindrical sidewall, a base and a top.

The rainwater inlet is preferably located at a lower end of a conduit that extends through the top of the tank to the lower region of the tank. The conduit can be, for example, a pipe, such as a PVC pipe. The lower end of the conduit can have a bend such that rainwater is expelled in the desired direction to produce the vortex. The lower end can be of reduced diameter relative to the remainder of the conduit, for increasing the flow rate of the rainwater through the rainwater inlet. An upper end of the conduit can be connected to, for example, a gutter of a roofed structure. The contaminated water outlet is preferably located at a lower end of a conduit and is in close proximity of the base of the tank. The conduit can be, for example, a pipe, such as a PVC pipe. The conduit can extend along a central axis of the storage tank and an upper end of the conduit can extend through the sidewall of the tank. The upper end of the conduit can be connected to a pump or syphoning means to draw out the contaminated water at the centre of the vortex, or the contaminated water can be expelled from the tank when the tank overfills with water and the water level is above the upper end of the conduit.

The tank can have a control valve such as a tap mounted to the tank sidewall and the portable water outlet can be located at an end of the control valve. Preferably, the potable water outlet is located just beneath the surface of the tank water. The potable water outlet is preferably located at an upper end of a conduit, such as a flexible tube. A float, connectable to the upper end of the flexible tube, can maintain the position of the potable water outlet just beneath the surface of the tank water. A lower end of the flexible tube can be connected to a control valve, such as a tap, mounted to the tank sidewall adjacent the base thereof. The control valve, or a pump, can regulate the flow of tank water from the flexible tube.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a conventional water storage tank containing contaminated water; Figure 2 is a cross-sectional view of a water storage tank when a vortex is produced therein; Figure 3 is a cross-sectional view of a water storage tank containing contaminated water according to an embodiment of the present invention; Figure 4 is a plan view of part of the water storage tank of Figure 3; and Figure 5 is a cross-sectional view of a water storage tank, like the tank of Figure 3, according to another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In all the drawings, like reference numerals refer to like features.

Referring first to Figure 1, there is shown a conventional water storage tank 1 having a rainwater inlet 2 located at an upper region of the tank 1 and an outlet 3 for water 5 located at a lower region of the tank 1. As sediment 4 collects at a bottom of the tank 1, it is clear that this is what is collected when water 5 is withdrawn through the outlet 3. It is to be noted that water 5 in tank 1 circulates vertically, as indicated by the arrows.

Referring now to Figure 2, when a vortex is created in a storage tank 6 containing water having entrained particular contaminants, the heavierthan-water contaminants 7 accumulate in a central lower region of the tank 6.

It is to be noted that water in tank 6 circulates horizontally, as indicated by the arrows.

Figures 3 and 4 show a polyethylene self-cleaning water storage tank 10 according to a first preferred embodiment of the invention. The tank has a top 11, a cylindrical sidewall 12 and a base 13. A rainwater inlet is located at a lower region of the tank 10, a contaminated water outlet 16 is located at a lower central region of the tank 10, and a potable water outlet 17 is located at the lower region of the tank The rainwater inlet 15 is located at a lower end of a 90 mm PVC pipe 18. Pipe 18 extends through an opening of the top 11. The lower end of pipe 18 has a bend such that the rainwater inlet 15 directs incoming rainwater in a circular motion around the lower region of the tank The contaminated water outlet 16 is located at a lower end of a 90 mm PVC pipe 20 that extends down a central axis of the tank 10 so as to terminate 20 mm above the base 13 of the tank 10. An upper end 21 of the pipe 20 extends through the sidewall 12 of the tank A tap 22 regulates the flow of water through the potable water outlet 17. In Figure 3, the outlet 17 is located at a lower region of the tank Figure 5 shows a polyethylene self-cleaning water storage tank according to a second preferred embodiment of the invention. The tank has the features of tank 10 except that the potable water outlet 17 is located just beneath the surface of the tank water 31. The potable water outlet 17 is located at an upper end of a hose 32. A float 33 with legs or a cage around it is connected to the hose 32 and keeps the potable water outlet 17 in position just beneath the surface 31 of the water. The cage prevents contaminants from being drawn into the hose 32 should the level of the water in the tank 10 drop to the lower region of the tank 10. A lower end of the hose 32 is connected to the tap 22.

In operation, rainwater from a roofed structure flows by way of rainwater inlet 15 to the lower region of the storage tank 10. Here the water is ejected around the sidewall 12 of the tank 10 as shown in Figure 4 and a vortex is set in place causing heavier-than-water particular contaminants (as indicated by the dotted lines) to migrate to the central lower region of the tank 10. The particulate laden water accumulates in the central lower region of the tank 10 and it can be passaged through the contaminated water outlet 16 for discharge to waste or, preferably, for grey-water usage purposes. The upper end 21 of pipe 20 can be connected to a pump or syphoning means to draw out the contaminants 40 at the central lower region of the tank 10, or the contaminants 40 can be expelled from the tank 10 when the tank 10 overfills and the water level is above the upper end 21 of pipe 20. Uncontaminated water can be drawn off for household usage by opening tap 22.

In this way, the tank is self-cleaning and uncontaminated water is made available to the consumer in an efficient and cost-effective manner.

Whilst the above has been given by way of illustrative example of the invention, many modifications and variations may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth.

Claims (11)

1. A self-cleaning water storage tank, said tank including: a rainwater inlet; a contaminated water outlet; and a potable water outlet, wherein the rainwater inlet is positioned at a lower region of the tank and expels water in a pathway which follows a perimeter of the lower region so as to produce a vortex within the tank, and wherein the contaminated water outlet is positioned at a lower central region of the tank so that contaminated water that has accumulated at the lower central region can be removed from the tank therethrough.

2. The self-cleaning water storage tank of claim 1, wherein the tank has a cylindrical sidewall, a base and a top.

3. The self-cleaning water storage tank of claim 2, wherein the rainwater inlet is located at a lower end of a conduit and the conduit extends through the top of the tank to the lower region of the tank.

4. The self-cleaning water storage tank of claim 3, wherein the lower end of the conduit has a bend.

The self-cleaning water storage tank of any one of claims 2 to 4, wherein the contaminated water outlet is located at a lower end of a pipe in close proximity of the base of the tank.

6. The self-cleaning water storage tank of claim 5, wherein the pipe extends along a central axis of the tank and an upper end of the pipe extends through the sidewall of the tank.

7. The self-cleaning water storage tank of any one of claims 2 to 6, wherein the potable water outlet is located just beneath the surface of the water in the tank

8. The self-cleaning water storage tank of claim 7, wherein the portable water outlet is located an upper end of a flexible tube and the other end of the flexible tube is connected to the sidewall of the tank adjacent the base thereof.

9. The self-cleaning water storage tank of claim 8 further having a float connected to the upper end of the flexible tube.

The self-cleaning water storage tank of claim 8 or claim 9 further having a control valve for regulating the flow of water through the potable water outlet.

11. A self-cleaning water tank substantially as hereinbefore described with reference to any one of Figures 3 to DATED this 11 th day of July 2003 Booth Holdings (QId) Pty Ltd By their Patent Attorney CULLEN CO