AU3555802A - Rainwater tank cleaning system - Google Patents

Description

-21)- Background: In many households dependent on the collection of rainwater as a source of drinking water, the Collection Area iS normally the house roof and the rainwater is stored in a tank that can be constructed of iron, polyethylene, or concrete and which is located on a level below and in close proximity to the house roof so that the water flows by gravity down to the spouting and the collection tank.

Wind blown seeds, leaves, sticks, pollen, sand, road dust, bird droppings and dead iDSect can accumulate on the roof.

A problem associated with rainwater stored'in a tank is a build-up of sediment and plant material, which has been carried off the roof along the spouting by the rainwater, and into the storage tank.

The sediment decaying, places an oxygen demand on the tank water. The process of decay can significantly lower the available oxygen, in the water.

Teeare devices to minimise the plant material which is carried off the roof devices such as screens that fit into the gutter to prevent the accumulation of leaves and filters or leaf diverters on the spouting outlet and/or the entrance to the tank, which, also minimnise the deposit of leaves in the tank. There devices do not however prevent smaller particles such as Pollen, road dust sand and broken parts of leaves and sticks from accumulating in the rainwater tank.

It is known. to vacuum out tanks to remove the build up of sediment, in the same manner that swimmning pools can be vacuumed out. The equipment to do so is expensive and it is normal for a bouseholder to engage an independent contractor to occasionally clean out the tank.

The cost of cleaning out a rainwater tank can be several hundred dollars.

As storage tanks are located below the roof, it is necessary to use a pump to either pump the water to a header tank to thus provide pressure to the household water system, or to use the pump itself to provide pressure to the househol d water system.

The pumps draw in and break down the water sodden plant material to minute but still visible particles Ihat contaminate the household -water supply.

These particles can be clearly seen. when a glass. of water is poured and are more obvious when water is; run into a bath.

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In addition the impurities flow into the hot water cylinder where they cause a build up of material within the cylinder itself.

The inventor has come up with a novel and inexpensive system for removing the build up of sediment from rainwater tanks.

Invention: In one broad aspect the rainwater cleaning system (tank-vaCT?4) comprises a pipe means having a closed end located on the floor of the tank and having an open end connectable to an outflow from the tank. Located near the closed end of the pipe is at least one hole, preferably a number of holes; the combined surface area of the hole or holes preferably equals the surface area of the outflow. The outflow pipe preferably+ bas at least one'aiT hoie on its upper surface which permits the ingress'of air and prevents the siphoning of water from the rainwater tank.

Drawings: The invention will now be further described by way of example only with reference to a preferred embodiment and to the attached drawings in which: Fig. 1 is a section view of a preferred embodiment of the present invention.

Fig. 2 is an exploded view of the pipe as shown in Fig. 1.

Fig. 3 is an exploded view of the overflow pipe shown in Fig. 1.

-Fig, 4 shows a flexible pipe as a second embodiment of the present invention.

Fig. 5 shows a pipe means having multiple pipes as a third embodinment of the present invention.

Shown in Fig. 1 is the tank-vat m system installed in a plastic rainwater tank I having an inlet 2 and an outlet 3. A rainwater pipe 4 from the roof disc harges water into the inlet 2.

When the water from the inlet 2 enters the tank the water level is r-aised above outlet 3 causing the tank to overflow.

The present invention comprises a polyethylene pipe 5 having six identically sized holes and IQOA out in the sides of the pipe 5. The free end. 1I of the pipe 5 is sealed usua.lly with a, cap 12. The other end 13 is attached to an elbow, 14 which is itself attached to a second pipe 104857FCAF.402.doc/HC/kc The pipe 15 is connected to a second elbow means 16 which is itself connected to the outlet pipe 3.

In Fig. 3 is shown an exploded view of the small holes 18 formed in outlet pipe 3 at 17, to prevent a siphoning effect from the invention. The discharge area of the outlet pipe 3 is the same as the total area of the holes 10 and 10A cut into the pipe S.

Working Example 1: A 150 litre tank was used for trials. A 40mm diameter PVC water pipe had one end sealed and six holes drilled into it. This pipe was placed on the base of the plastic water tank. The surface area of the six boles equalled the surface area of the discharge outlet for maximum outflow. Various types of sediment were placed in the tank and the tank was caused to overflow. When the tank overflowed the sediment was drawn into the six holes in the pipe and exited from the tank via the outlet. The amount of sediment exiting the tank could be clearly measured from observing changes in the colour of the water exiting the tank.

Regardless of whether leaves, dirt or sand particles were used as sediment, the result was an almost instant removal of the sediment whenever the tank overflowed.

Working Example 2: In a similar manner to Example 1 the invention was trialled on a 4,000 gallon rainwater tank.

The only difference was that an 80 mm PVC water pipe was used rather than the 40mm PVC pipe. Again six holes were drilled in the pipe and sediment was added to the tank. When the tank was caused to overflow, the sediment was drawn out of the tank through the holes in the pipe.

When water flows from the house roof and enters the inlet 2 of the tank; rather than flowing directly through the outflow 3, the tank-vacT' system causes the water at the base of the tank to enter the holes 10 and 10a located in the pipes at the base of the tank 1. The water entering the holes in the 10 and 10a pipe 5 draws in the sediment, plant material, dirt and other particulate solids on the base of the storage tank and by siphon action washes them out through the overflow 3. In this way the fresh water entering the tank is not immediately reroved by the overflow and the tank is automatically cleaned.

The tank-vacTM overflow system provides for cleaning of the rainwater tank whenever the water storage system begins to overflow.

S04S57FC.APF.4E2A.MC/WAe As seen in Fig.. 2 the section of pipe 5 that lies on the base of the tank has a number of holes and IlOa drilled into the side of the pipe. The size of the holes and the number of holes and IlOa can be varied to take account of particu] ar contaminant problems.

If large leaves have been drawn into the water storage system then the holes in the flexible pipe can be made of sufficient diameter to allow the leaves to be drawn into the pipe and discharged from the overflow.

Whilst the cleaning action will work regardless of the size and number of holes i the pipe it is preferably that the total surface area of the holes drilled into the tank-vac~m pipe equal the surface area of the water tank overflow. The. suction is maintained thr~ough the siphon system. This invention allows the older less oxygenated water in the tank to be expelled whenever fresh water enters the tank.

To prevent excess water siphoning from the storage tank the tank-vac system is controlled by forming of at least one air hole in the top of the overflow pipe and on the outside of the tank.

It is envisaged that the invention would be sold as a kit with instuctions. The kit comprising the following: A pre-drilled pipe for the base of the tank; An end cap for the pre-drilled pipe; A pipe to rise uip the inside of the tank; Two right-angled bend&; pvc solvent glue; A square of fine mesh In tanks which are not readily accessible, it may be necessary to make a new overflow outlet or to position the pipe within the tank by means of mechanical tongs.

Whilst the invention has been described with particular reference to a rigid pipe, it is quite clear that the invention will also work with flexible piping as shown it Fig. 4, which will allow for movement of the pi1pe around the base of the tank.

In place of a single pipe multiple pipes can be used as shown in Fig. 104157FCAPFA.4odR'qCc