WATER STORAGE FACILITY
TECHNICAL FIELD
This invention relates to improvements in facilities for storing water, and particularly relates to a specially designed water tank and a method of placing the water tank on a ground surface.
BACKGROUND ART Water storage tanks are extremely important in areas beyond the reach of reticulated water. Even in areas where reticulated water is available, water tanks are still used to store rain water. More recently, storage and re-use of grey water is becoming more common.
Existing water tanks are most commonly used to catch roof water, but there is also a need for water tanks to catch and store run-off surface water.
To date, water tanks are commonly formed from rigid steel or plastic materials. In order to prevent leakage, the tanks are manufactured in as few pieces as possible (usually off site) and are then transported to the required position. Transport of rigid tanks is difficult and expensive and the large rigid tanks require extensive site preparation. Existing tanks are usually formed from concrete which is prone to cracking, steel which is prone to rusting; and plastic which is rather soft and is fairly easily pierced. All conventional tanks require emptying to enable cleaning, and entry and removal of debris is only possible through a limited opening in the roof. Existing tanks are difficult if not impossible to place in narrow areas or areas having small access points. DISCLOSURE OF THE INVENTION
The present invention is directed to a water tank which may overcome at least some of the abovementioned disadvantages or provide the public with a useful or commercial choice.
In one form, the invention resides in a flexible water tank comprising a flexible bladder having a bottom wall for contact with a ground surface, an inlet at one end region of the bladder and adjacent the bottom wall, and an outlet at an opposed end region of the bladder and also adjacent
the bottom wall.
In another form, the invention resides in a flexible water tank comprising a flexible bladder having a bottom wall for contact with a ground surface, an inlet, an outlet, a top wall and at least one internal tie extending between the bottom wall and the top wall to prevent the top wall from ballooning out when the bladder is filled with water.
In another form, the invention resides in a method for collecting and storing water in a water tank, the method comprising providing a flexible water tank which has a flexible bladder having a bottom wall for contact with a ground surface, an inlet at one end region of the bladder and adjacent the bottom wall, and an outlet at an opposed end region of the bladder and also adjacent the bottom wall, placing the bladder on a sloping ground surface such that the inlet is higher than a major portion of the bladder.
The flexible water tank having an inlet and an outlet both adjacent the bottom wall of the tank allows the tank to be used on slopes. For instance, the flexible tank can be placed on a slope with the inlet at the top and the outlet at the bottom and this allows the tank to be filled from ground water.
To assist in the filling action, it is preferred that a water catchment sheet, skirt or like member is placed in front of the inlet such that rain water or surface water falling onto the sheet or skirt is funneled towards and through the inlet. The sheet or skirt can be of any desired size to suit.
The flexible water tank can be of various sizes and shapes and it is envisaged that the water tank can hold between 5,000 - 50,000 litres or more.
The water tank can be made of any suitable flexible material which should have suitable qualities in meeting drinking standards, tear resistance and weathering. The tank could be made from one or more flexible sheet members which can be attached together in a watertight manner, for instance by welding or gluing.
The inlet and the outlet may be formed from tubes which can be attached to the flexible bladder. These tubes can have a diameter of
between 5 - 20cm and preferably have a diameter of approximately 10cm. The tubes may be round, polygonal or other configurations.
The outlet is suitably associated with a valve mechanism to allow water to be removed from the bladder when required. It is also envisaged that from time to time the bladder needs to be flushed to remove any debris and it is preferred that the valve arrangement is able to fully open to assist in the flushing action.
In order to facilitate debris removal, it is preferred that the outlet region of the tank is tapered towards the outlet such that any debris is collected adjacent the outlet area.
To prevent the flexible bladder from ballooning outwardly, it is preferred that the top wall of the bladder is tied for instance to the bottom wall of the bladder, by one or more internal ties or partitions. In one form, the internal ties comprise tubes which extend from the inside of the bottom wall to the inside of the top wall and are joined at both walls to hold the walls in a spaced relationship. These tubes can be formed from rigid plastic or similar material to provide the entire bladder with a degree of dimensional stability. It is preferred that the tubes are slotted or otherwise perforated such that water can flow into the tubes in order to maximise the internal usable volume of the bladder. The tubes could be formed from flexible material which will allow bladder to adopt a "lay flat" configuration and can allow the tank to be rolled up or folded when not in use, or during transportation either to a site or between sites.
By having a flexible bladder, site preparation is not as stringent, it being only required that the site is cleared of sharp objects and is reasonably even and cleared. The site should be slightly inclined in order to allow the bladder to fill with water. However, it could be envisaged that the inlet could be L-shaped or upwardly inclined to allow the bladder to be filled even on a substantially level site. In one form, the flexible water tank can be anchored to the ground surface. This can be achieved by anchoring means which could comprise pins or pegs. In an embodiment, the flexible bladder can be
provided with at least one attachment which allows a peg or like member to pin the bladder to the ground surface. The at least one attachment can be in the form of an elongate skirt which can extend adjacent the inlet of the flexible bladder with the skirt being formed with a number of eyelets or holes through which anchoring pegs can be driven.
The flexible water tank can have a relatively low profile and, for instance, can be approximately 50 - 100cm above the ground surface. The volume of the tank can vary depending on the ground conditions and the slope but can be between 5,000 - 50,000 litres or more. The tank can be positioned directly on a sloping ground surface and can be used to collect run-off ground water. Alternatively, the tank can be attached to the downpipe of a roof to collect rain water, or to a grey water outlet pipe to collect and store grey water for possible re-use. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described with reference to the following figures in which
Figure 1 is a schematic side view of a flexible water tank according to an embodiment of the invention.
Figure 2 is a top view of the tank of Figure 1. Figure 3 is a view of the inlet end of the tank of Figures 1 and 2.
Figure 4 is a view of the outlet end of the tank of Figures 1 and 2.
BEST MODE Referring to the figures, there is shown a flexible water tank 10 which comprises essentially of a flexible bladder 11 which has a bottom wall 12 which sits on the ground surface, a top wall 13, and inclined front wall 14, and a back wall 15 which tapers when viewed in plan and which is better illustrated in Figure 2. Bladder 10 has an inlet 16 and an outlet 17 both of which are adjacent bottom wall 12. Top wall 13 and bottom wall 12 are tied together through a number of vented tubes 18 which are illustrated in Figures 2 and 4. Vented tubes 18 are formed from the same tube material as inlet 16 and outlet 17 to
economize on parts. Tubes 18 extend inside bladder 11 and do not perforate either the top wall or the bottom wall. The tubes themselves are slotted, apertured or otherwise vented inside the bladder such that they can fill with water and therefore maximise the available internal volume of bladder 11. Bladder 11 is made from any flexible material with suitable qualities in meeting drinking standards, strength, tear resistance and weather resistance.
The outlet end 15 of the water tank is tapered as illustrated in Figure 2 in order to facilitate debris removal. The inlet end 14 tapers as illustrated in Figure 1 to a reinforced seam 19 formed with holes 20. Holes 20 allow anchoring pegs (not shown) to be driven into the ground to enable the water tank to be fixed onto steeper slopes where anchoring may be required.
The flexible water tank can be collapsed to a fairly small volume making transportation to a site less costly and easier.
By having the inlet and outlet at ground level, the tank can more easily collect run-off ground water especially if a collecting sheet or skirt is pegged in front of the tank.
It should be appreciated that various other changes and modifications can be made to the embodiment described without departing from the spirit and scope of the invention as claimed.