WO2004065701A1

WO2004065701A1 - Rainwater filtration and collection system

Info

Publication number: WO2004065701A1
Application number: PCT/GB2003/005711
Authority: WO
Inventors: Nicholas John Trincas
Original assignee: Nicholas John Trincas
Priority date: 2003-01-23
Filing date: 2003-12-31
Publication date: 2004-08-05
Also published as: GB0330205D0; AU2003295174A1; GB2397537A

Abstract

The filter-separator device (1) is connected into a rainwater disposal pipe of a building to divert rainwater for collection. A horizontal barrier (7) is placed in the pipe with an outlet (9) above and adjacent to the barrier (7). A perforated funnel (4) extends through the barrier (7). The upper periphery of the funnel (4) extends towards the walls of the pipe above the outlet to define a separation gap (10) of width no more than two millimetres to allow flow of relatively clear water, while further clear water may flow through the perforations of the funnel (4).

Description

RAINWATER FILTRATION AND COLLECTION SYSTEM

The present invention relates to a system for filtering, collecting and storing rainwater for domestic or commercial use. More particularly, but not exclusively, it relates to a system for intercepting rainwater run-off from a roof surface so that it may be used for purposes such as toilet flushing, clothes washing and any other purpose not requiring water of potable quality. The invention further relates to filters for rainwater for use in such a system and also to an underground storage tank for use therein. The invention also relates to such a system to supply collected rainwater, further treated to be usable for bathing, or even to be potable.

In a modern British household, water usage is typically around 135 litres per day, according to Environmental Agency figures, with over 10% of this being poured straight down the drain. Toilet flushing accounts for around 35% of average domestic water consumption, and this can be even higher in a commercial situation - 65% of total water consumption has been quoted in this sector. There is no need to use drinking water to flush a toilet. Similarly, watering the garden does not need potable water, and it has found that a washing machine can run perfectly well on rainwater. Indeed, in areas where the water supply is hard, a washing machine may run better on soft rainwater. At least half of domestic water requirements could be fulfilled with rainwater instead of expensively purified and piped drinking water, and the volume of rain falling on the roof of a typical British house annually should be sufficient to fill such requirements with water to spare.

Furthermore, water supply companies are increasingly encouraging consumers to pay for domestic water supplies on the basis of a metered supply, instead of by means of a single flat- rate payment irrespective of the actual usage. A significant proportion of sewerage charges effectively constitutes a payment for taking away the rainfall that runs off roofs, through guttering and downpipes and down to the sewers. It therefore makes increasing financial sense to individual consumers, as well as environmental sense to society as a whole, to replace potable water usage with collected rainwater wherever possible.

Systems for collecting, storing and delivering rainwater have been known for several years. However, they have not been widely adopted, particularly in the domestic market. Presumably, whatever the day-to-day savings possible once a system has been installed, the capital cost of existing systems, and the cost and effort required to install them, has discouraged many potential users - particularly if they are considering adding such a system to an existing house, rather than incorporating it from scratch in a new construction.

Particular problems may arise from the extent of the excavation required for the installation of underground storage tanks for the collected rainwater, together with their ancillary apparatus such as filters. It is also believed that the filters currently employed in such systems are unnecessarily complex and expensive, and a system using simpler filters having the necessary performance would achieve more widespread adoption.

While current UK legislation limits the use of collected rainwater, however treated, as a potable water supply, it is believed that this may change in the near future. In any case, such a ban does not exist in many other countries, particularly but not exclusively those with a less-developed infrastructure than the UK. There is hence a need for rainwater collection systems as outlined above, which are also capable of delivering water treated to drinking water standards and hence usable for almost any domestic or commercial purpose. Again, such a system should be as simple to install and use as possible, to encourage its adoption.

Even where legislation inhibits the use of treated rainwater for drinking purposes, it would be beneficial to treat rainwater to the standards set for personal bathing purposes, which are significantly above those set for supplies to washing machines and toilets.

It is therefore an object of the present invention to provide a system for collecting, filtering and storing rainwater which requires a minimum of excavation for its installation. It is also an object of the present invention to provide a system for collecting, filtering and storing rainwater having simpler and effective filtration means, and to provide such filtration means usable in a rainwater collection system. A further object is to provide a storage tank adapted for use in such a rainwater collection system. Another object is to provide such a system capable of delivering a supply of water for bathing purposes or of potable water. According to a first aspect of the present invention, there is provided a system for collecting, filtering and storing rainwater comprising means to divert rainwater from rainwater disposal means of a building, first means to separate suspended solid material from said rainwater and means to store said rainwater for subsequent use, wherein said first separating means and said storage means are located in a common subterranean cavity.

Preferably, said first separating means is mounted to an upper part of said storage means.

The first separating means preferably comprises filtration means, optionally comprising a filter mesh having a nominal aperture size of less than 200 microns.

The filter mesh may have a nominal aperture size of less than 5 microns, where the water is to be used for potable but non-drinking uses.

Advantageously, the system may also comprise second separating means adapted to separate entrained debris from said rainwater, optionally to separate material having a particle size exceeding one millimetre from said rainwater.

Said second separating means may be incorporated into the diverting means.

The diverting means may then comprise a filter-separator device as described in the second aspect below.

The diverting means may be mounted to a downpipe or the like mounted between guttering on a building and drainage means thereof. The diverting means may be provided with a means selectably to allow rainwater to pass into the system, which may optionally be automatically controlled, for example in response to a water level within the storage means.

The system may be provided with a plurality of diverting means, each mounted to respective downpipe means and all connected to a common first separating means and storage means.

According to a second aspect of the present invention, there is provided a filter-separator device adapted to be mountable to a rainwater disposal means of a building to divert rainwater therefrom for collection, and comprising a hollow vessel open at an upper and a lower end and divided into an upper and a lower chamber by generally horizontal barrier means, outlet means extending outwardly from the upper chamber adjacent said barrier means and funnel means extending from within the upper chamber through said barrier means to the lower chamber, wherein an upper periphery of the funnel means extends towards the walls of the upper chamber above the outlet means to define a separation gap therebetween.

Preferably, said separation gap has a width of no more than two millimetres.

Advantageously, said gap has a width of between one-tenth of a millimetre and one millimetre, optionally of approximately one half of a millimetre.

Preferably, the outlet means is connected to rainwater collection means and the lower chamber is connected to drainage means. Rainwater may then pass into the hollow vessel through its upper end and impinge upon the gap, solid material larger than the separation gap being swept into an interior of the funnel means and thence into the lower chamber and out of the vessel.

The funnel means may optionally comprise filter mesh means, such that water may also pass from an interior thereof towards the outlet means.

The filter-separator device is preferably adapted to be mounted to a downpipe.

The hollow vessel may then be adapted to connect to said downpipe at the upper and lower ends of the vessel.

The filter-separator device may be provided with means selectively to guide water away from said separation gap and towards the lower chamber, thereby halting collection of rainwater.

According to a third aspect of the present invention, there is provided a filtration device for rainwater comprising first chamber means provided with inlet means, second intermediate chamber means, and third chamber means provided with first outlet means for filtered water, wherein filter mesh means are provided between the second and third chamber means, and the first and second chamber means are connected by separation gap means.

Preferably, the first chamber means is provided with means to divert water entering through the inlet means towards the separation gap means. The first chamber means may be provided with second outlet means for water carrying solid material unable to pass through said separation gap means.

The filter mesh means may comprise a mesh of metal, optionally stainless steel, having a nominal aperture size of no more than 200 micrometres, advantageously having a nominal aperture size of no more than 125 micrometres, optionally of no more than 20 micrometres, and in some cases, no more than 5 micrometres.

The filter mesh may extend within and spaced from the walls of the second chamber means to define the third chamber means within the second chamber means.

The separation gap means may be disposed generally above an upper periphery of the filter mesh means to guide water passing through the gap means towards the filter mesh means.

The separation gap means preferably comprises an elongate narrow gap having a width of no more than two millimetres, advantageously of between one millimetre and one-tenth of a millimetre, and optionally of approximately one-half of a millimetre.

The separation gap means may be defined by flange means extending from a wall of the first chamber towards the diverter means.

The diverter means may comprise a generally conical body with the separation gap means extending around a basal periphery thereof. The flange means may extend towards said basal periphery of the conical body, leaving a gap of substantially constant width.

Alternatively, the flange means may extend generally parallelly to the conical body adjacent its basal periphery, spaced therefrom by a gap of substantially constant width.

The filtration device is preferably mountable to a storage tank for filtered rainwater, optionally directly mountable to a filling inlet in an upper surface thereof.

According to a fourth aspect of the present invention, there is provided a storage tank adapted for subterranean use in a rainwater collection system, provided with rainwater filtration means mounted to an upper portion thereof.

Preferably, said rainwater filtration means comprises a filtration device as described in the third aspect above.

Advantageously, said filtration means is housed within turret means extending upwardly from a main body of the storage tank.

According to a fifth aspect of the present invention, there is provided a water filtration and supply apparatus, mountable to a water storage tank, comprising water filtration means, water supply means connectable to a premises to be supplied, pressure sensing means linked to said water supply means and control means therefor. Preferably, the apparatus comprises container means enclosing at least said water filtration means and said control means.

Advantageously, the container means is divided into two chamber means, a first containing the water filtration means and a second being waterproof and containing the control means.

The apparatus may be mountable to an upper portion of a subterranean storage tank, optionally to turret means extending upwardly from a main body of the storage tank.

The apparatus may comprise pump means locatable within the storage tank and controllable by the control means.

The control means may be adapted to operate the pump means when the pressure sensing means detects water being taken from the water supply means.

The apparatus may be provided with means to sense the water level within the tank.

The control means may be adapted to halt operation of the apparatus when said water level falls below a preselected level.

The water filtration means may comprise a filtration device as described in the third aspect above.

In a preferred embodiment, the apparatus comprises water sterilisation means. Advantageously, the water sterilisation means comprises ultraviolet light irradiation means.

The apparatus may also comprise additional water filtration means comprising a porous, optionally microporous, solid filtration medium.

Said solid filtration medium may comprise activated carbon, optionally also comprising silver.

Said water sterilisation means and/or said additional water filtration means may be located within said waterproof second chamber means.

Preferably, the apparatus also comprises means to monitor and display to a user operating data such as a volume of water held within the tank and indications concerning any malfunctions which may occur.

The monitoring and display means may be provided with means to convert water level data to volumetric data, for example taking into account the shape of the tank.

The monitoring and display means may be provided with memory means to store malfunction indications, including date and time indications, for subsequent use in the course of repair and maintenance work.

The apparatus may be provided with electrical power storage means adapted to provide power thereto in the absence of mains electrical power. The electrical power storage means may be charged from a mains electrical power supply.

Alternatively or additionally, it may be charged by electricity generating means linked directly thereto.

Said electricity generating means may comprise solar or wind-powered electricity generating means.

According to a sixth aspect of the present invention, there is provided a storage tank adapted for subterranean use in a water supply system, provided with a water filtration supply apparatus as described in the fifth aspect above, mounted to an upper portion thereof.

Preferably, said water filtration and supply means is mounted to turret means extending upwardly from a main body of the storage tank.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which:

Figure 1 shows, in schematic cross-section, a filter-separator unit of the present invention, for use in a downpipe;

Figure 2 is a side elevation of the filter-separator unit of Figure 1;

Figure 3 shows, in schematic cross-section, a variant of the unit of Figure 1;

Figure 4 shows, in schematic cross-section, a further variant of the unit of Figure 1;

Figure 5A shows, schematically, an existing rainwater collection system; Figure 5B shows, schematically, a rainwater collection system of the present invention;

Figure 6 shows, in schematic cross-section, a first tank-top filter unit of the present invention;

Figure 7 shows the preferred arrangement of the filter unit of Figure 6 together with an underground storage tank;

Figure 8 is a cross-sectional elevation of a second tank-top filter unit of the present invention;

Figure 9 is a cross-sectional elevation of a third tank-top filter unit of the present invention;

Figure 10 is a cross-sectional elevation of a fourth tank-top filter unit of the present invention;

Figure 11 is a cross-sectional elevation of a fifth tank-top filter unit of the present invention;

Figure 12 is a plan view of a tank-top filter, purification and control unit of the present invention;

Figure 13 is a cross-sectional elevation of the filter, purification and control unit of

Figure 12 in place on an underground storage tank; and

Figure 14 is a plan view of a tank-top filter and control unit of the present invention.

Referring now to the Figures, and to Figures 1 and 2 in particular, a filter-separator unit 1 is dimensioned to be fitted into a conventional downpipe leading generally downwardly from a roof gutter to a rain gulley, drain, sewer or soakaway. The unit 1 is provided at its upper 2 and lower 3 ends with connection fittings (not shown) compatible with the particular downpipe used. The unit 1 is provided with a funnel 4 comprising a frustocomcal upper portion 5 and a generally cylindrical lower portion 6. An annular floor 7 extends between the funnel section 4 and a wall 8 of the unit 1. A side spout 9 extends generally horizontally through the outer wall 8, its lowest surface being level with the floor 7.

The frustocomcal portion 5 of the funnel 4 extends towards the walls 8 of the unit 1 , leaving a narrow gap 10 approximately half a millimetre wide between its upper rim and the wall 8. The frustocomcal portion 5 comprises stainless steel or another metal, and in one embodiment forms a continuous surface, while in an alternative embodiment it comprises a filter mesh, ideally a mesh with a nominal aperture size of approximately 125 microns. Where the water is to used for potable, but non-drinking, purposes, it is advisable for the mesh to have a nominal aperture size of approximately 5 microns.

In use, rainwater from the roof guttering flows down the downpipe into the upper end 2 of the unit 1, normally mainly following the walls 8, as shown by arrows 11. This water may contain both fine suspended material and coarser debris, such as leaves, bird droppings, mould and the like, washed off the roof and into the gutter. This coarse debris cannot pass through the gap 10 between the upper rim of the frustocomcal portion 5 and the walls 8, and is washed into an interior of the funnel 4, being led through the lower portion 6 thereof and out through the lower end 3 of the unit 1 to drain, as in a conventional downpipe.

However, a substantial proportion of the water passes through the gap 10, following arrows 12. The continuous floor 7 prevents flow down the downpipe, and so this water exits through the side spout 9, which leads to a storage tank (see below). When the frustoconical portion 5 comprises a filter mesh, a proportion of the water which flows into the interior of the funnel 4, carrying the coarse debris, passes outwardly through the mesh and joins the water which has passed through the gap 10 in flowing out through the spout 9. In this case, some debris may be left on or around the funnel 4 until there is a sufficiently great flow of water (e.g. in a rainstorm) to wash it across the mesh without all the water being diverted to the spout 9. Selection of units 1 with and without mesh portions 5 thus depends on a desired compromise between maximum collection of rainwater and the amount of debris to be swept to drain.

The filter-separator unit 13 of Figure 3 is similar to the unit 1 of Figure 1, with the addition of a pivotable diverter flap 14 adjacent its upper end 2. The diverter flap 14 is controllably pivotable between a generally horizontal disposition as shown and a generally vertically extending disposition. In its generally vertical disposition, the flap 14 does not interfere with water flow through the unit 13, which operates as described above for the unit 1 of Figure 1.

In its generally horizontal disposition, the periphery of the flap 14 approaches the walls 8 of the unit 13, disturbing the even flow of water, and diverting flow onto the funnel 4 of the unit 13 and thence to drain.

The filter-separator unit 13 is usable to prevent over-filling of a rainwater storage tank. In existing systems (see below), such a tank is usually provided with an overflow system leading to a drain, sewer or soakaway. However, it is inefficient to lead rainwater completely through a filtration and collection system, only for it to be passed to drain. A level sensor is therefore provided within the storage tank which sends a signal to control gear for the diverter flap 14 when the storage tank is close to full. The diverter flap 14 is then pivoted to its horizontal disposition, preventing rainwater from flowing through the side spout 9 to the storage tank and instead diverting it directly to drain.

The filter-separator unit 15 of Figure 4 has the additional feature that it has an aperture 16 extending generally centrally tlirough its diverter flap 17. The aperture 16 may comprise a simple hole or may have a frustoconical surround 18 as shown. In either case, when the apertured diverter flap 17 is vertically aligned, rainwater flows tlirough the unit 15 as described for the unit 1 of Figure 1. When the apertured diverter flap 17 is pivoted into its horizontal disposition, its periphery contacts the walls 8 of the unit 15, interrupting water flow along the walls 8. Instead, the water passes through the aperture 16 and streams downwardly, through an axial zone of the funnel 4, to drain. None of this water will reach the gap 10 and pass therethrough to the side spout 9, and it will also be guided away from the frustoconical portion 5 of the funnel 4 (which may, as above, optionally comprise mesh).

In both units 13, 15 having a diverter flap 14, 17, the flap 14, 17 may controllably be pivoted in either direction using a low voltage electric motor, or it may be pivoted against a spring biased to return it to a preferred disposition (usually one in which water is diverted away from the storage tank, as a fail-safe).

Figures 5A and 5B show an existing rainwater collection system and an improved system embodying the present invention, respectively. Each is shown in connection with a conventional dwelling house 19, although they are equally applicable to commercial, industrial or agricultural premises. In the conventional system, rainwater run-off from a roof 20 passes to a downpipe 21 provided with a separator 22 which separates a debris-laden stream which continues to drain

23 from a stream of water containing only finer suspended material, which is led to a bottle gulley 24. Several downpipes 21 can be connected to a common bottle gully 24.

A number of types of separator 22 are currently available, although the filter-separator units 1, 13, 15 described above could also be used in their place in a conventional system, providing a degree of improved performance and/or economy.

From the bottle gulley 24, the rainwater is conventionally piped to a first pit 25, which contains a fine filtration unit 26. The fine filtration unit 26 separates a majority of the suspended material from the rainwater, leaving only the finest particulates. These will have no harmful effects, should water containing them be used for flushing toilets, for example. It has also been found that they have no effect on the cleaning efficiency of modern clothes washing machines. The fine filtration unit 26 is conventionally a complex device such as a vortex filter, requiring considerable capital outlay.

From the fine filtration unit 26, the filtered rainwater flows down to an underground storage tanlc 27, buried in a second pit which has been backfilled leaving an inspection chamber 28 extending to ground level. The storage tank 27 has an overflow 29 leading to a sewer or a deep soakaway. The fine filtration unit 26 has a pipe 30 tlirough which separated suspended material is led to waste, either via the tanlc overflow 29 or to a separate sewer connection or deep soakaway. The conventional system can be difficult to install correctly, as it relies on correct relative levels and gradients between the bottle gulley 24 and the first pit 25 containing the fine filtration unit 26, and between the fine filtration unit 26 and the storage tank 27. This is made more difficult by the uneven "ground levels" frequently encountered in practice. The net result is that the second pit for the storage tank 27 usually has to be dug deeper than otherwise strictly necessary, merely to accommodate the correct gradients between the various components.

As a rule, water stored more than 450mm below ground level never becomes cold enough' to freeze. It is therefore unnecessary to bury a storage tank 27 more than about 500mm below ground level. Furthermore, the inspection chamber 28 in the conventional system is wasted space, except in the very rare event that access to the tank 27 is needed.

The rainwater collection of the present system therefore differs by having a fine filtration unit 26 located within the inspection chamber 28, as shown in Figure 5B. This system is identical to that shown in Figure 5 A up to the bottle gulley 24, although it is preferred to use one of the filter-separator units 1, 13, 15 described above as the separator 22.

Only a single pit need be dug to accommodate the storage tanlc 27 and the fine filtration unit 26.

With the correct choice of fine filtration unit 26 (eg see below), it is straightforward to provide a single connection between the bottle gully 24 and the fine filtration unit 26 having a suitable gradient, with the inspection chamber 28 being no more than 500mm deep. The depth of the pit can thus be kept to a minimum. A soakaway for the overflow 29 and the waste pipe 30 can also be provided at a lesser depth than for existing systems.

Many storage tanks 27 are provided with a "turret" on their upper surface to which inspection hatches may be fitted. It is envisaged that storage tanks 27 for use in the present system could be produced with a turret approximately 500mm tall, which could form an inspection chamber 28 of suitable dimensions, and be adapted to contain the fine filtration unit 26.

One example of a fine filtration unit 26 adapted for use in the present system (and possibly also of benefit in existing systems) is shown in Figure 6. The inspection chamber 28 has an inlet 31 for collected rainwater, which flows on to a filter screen 32 extending across the chamber 28. This filter screen 32 comprises a filter mesh, conveniently of stainless steel and having a normal aperture size of 125 microns. A portion of the rainwater, containing particulates unable to pass through the filter screen 28, exits tlirough an outlet 33 leading to a sewer or soakaway as described above. A remainder of the rainwater passes downwardly through the filter screen 32 and enters the storage tanlc 27 tlirough a tanlc inlet 34, which is provided with one of a number of known "calming" arrangements. The inspection chamber 28 has an inspection hatch 35 through which the filter screen 32 may periodically be inspected and cleaned if necessary. The entire filter screen 32 may be removed for access to the storage tank 27 itself.

Figure 7 shows how the storage tanlc 27 and inspection chamber 28 are co-located beneath ground level, with only the inspection hatch 35 exposed once the system has been installed. A second form of fine filtration unit 26 is shown in Figure 8. The inspection chamber 28 is provided with an inlet 31, an outlet 33 and a tank inlet 34 as described above. A substantially cylindrical filter element 36 is located within the inspection chamber 28 with its axis substantially vertically aligned. An upper part 37 of the walls of the filter element 36 comprises a stainless steel filter mesh, which may be as fine as twenty micron nominal aperture size, while a lower portion 38 thereof is unperforated. The filter element 36 is replaceably removable, the lower portion 38 locating holdingly around a flow wedge ring 39 mounted to a floor of the inspection chamber 28. An annular lip 40 encircles the inspection chamber 28 adjacent an upper edge of the filter element 36, extending towards the filter element 36 and thereby forming a narrow gap 41 approximately half a millimetre wide. A non-perforated stainless steel deflector cone 42 is mounted to an upper end of the filter element 36.

In use, rainwater enters through the inlet 31 and falls on to the deflector cone 42, breaking up its flow. A majority of the water then passes through the narrow gap 41, entering a cylindrical zone 43 surrounding the filter element 36. A remainder of the water flows out of the inspection chamber through the outlet 33, carrying any suspended material unable to pass tlirough the gap 41. Water passing through the gap 41 tends to flow down an outer surface of the filter mesh of the filter element 36 and then pass therethrough. Particulates unable to pass tlirough the filter mesh collect in a sump zone 44 adjacent the unperforated lower portion 38 of the filter element 36. The sump zone 44 should be cleaned out periodically. In practice, it is found that the cylindrical zone 43 and the sump zone 44 can be as little as fifty millimetres wide, and the sump zone 44 and lower portion 38 of the filter element 36 can be as little as twenty five millimetres deep. The flow wedge ring 39 slopes downwardly from its outer periphery towards the centrally located tank inlet 34, to guide the flow thereinto of water passing tlirough the filter element 36.

A third form of the fine filtration unit 26 is shown in Figure 9, which is similar to the second form but has an inlet 31 disposed generally vertically above the deflector cone 42. In place of the generally horizontal lip 40 shown above, this unit 26 has a frustoconical lip 45 which extends generally in alignment with and slightly overlaps with a lower periphery of the deflector cone 42, again leaving a narrow gap 41 of around half a millimetre in width. A coarse filter mesh 46 may optionally be provided, immediately beneath the gap 41. The remainder of the filtration unit 26 is very similar to that shown in Figure 8. An upper section 47 of the unit is detachable to allow access to the filter element 36, e.g. for cleaning.

In use, water flows down the inlet 31 and contacts the diverter cone 42, flowing down its surface to the gap 41. A majority of the water passes tlirough the gap 41 (and optionally the coarse mesh 46) and is filtered tlirough the filter element 36 as described above. A remainder of the water, carrying material unable to pass through the gap 41, flows down an upper surface of the frustoconical lip 45 and then out through one or more outlets 33. This arrangement may provide more effective flow patterns than that described above.

Figure 10 shows a fourth form of the fine filtration unit 26, which is very similar to the unit 26 of Figure 8, except adjacent its tank inlet 34. This unit 26 omits the flow wedge ring 39 of the unit 26 of Figure 8. A chimney 48 extends upwardly from the tank inlet 34 and acts, in use, as a weir. Water passing through the walls of the filter element 36 accumulates until it reaches a level 49 at which it overflows an upper end of the chimney 48 and cascades through the tanlc inlet 34 into the storage tank 27. The filter element 36 has an annular base 50 which locates over the chimney 48 to hold the filter element 36 in position. When the filter element 36 is removed for cleaning, the chimney 48 prevents debris, for example debris which has collected in the sump zone 44, from entering the tank inlet 34 and the storage tank 27.

Figure 11 shows a fifth form of the fine filtration unit 26. This is very similar to the unit 26 of Figure 9, except that it omits the flow edge ring 39, it is provided with a chimney 48 extending upwardly from the tanlc inlet 34, and its filter element 36 has an annular base 50 which locates around the chimney 48, as for the unit 26 of Figure 10. As for the unit 26 of Figure 10, the chimney 48 acts as a weir when the unit 26 is in use, and prevents debris entering the tank inlet 34 when the filter element 36 is removed for cleaning.

Figures 12 and 13 show an integrated tank-top unit 51, mounted to the turret of an underground storage tank 27. The integrated unit 51 is divided into two chambers, a "wet" chamber 51 and a "dry" chamber 53, by a waterproof barrier wall 54. The integrated unit 51 has a one-piece cover 55 (omitted from Figure 12 to show an interior of the unit 51) provided with sealing strips 56 of silicone or other elastomeric material. Alternatively, a separate cover may be provided for each chamber 52, 53. In either case, the cover 55 or covers can be removed to allow maintenance, cleaning or the like.

The wet chamber 52 contains a fine filtration unit 26. While a fine filtration unit 26 as shown in Figure 8 is here in use, any of the alternative fine filtration units 26 described above may be used, or even a mesh filter of conventional design. Water exits the filtration unit 26 through the tank inlet 34 and flows into the storage tank 27 via a calming inlet 57 at a lower end of the tank inlet 34. The filtration unit 26 is removable for cleaning and for access to an interior of the storage tank 27.

The integrated unit 51 is preferably used in conjunction with a submerged pump 58, which stands on a floor of the storage tanlc 27 adjacent the tanlc inlet 34, for ease of access for installation, removal and maintenance. The submerged pump 58 is provided with a flexible or pivotably mounted intake tube 59, suspended at its end remote from the pump 58 from a float 60. The intake tube 59 is provided adjacent the float 60 with a water intake unit 61 comprising a suction filter and a non-return valve. Thus, the submerged pump 58 can only pump water out of the tank 27 from immediately below a water surface, remote from any sediments that may have collected on the floor of the tank 27, despite all the filtration steps employed. The submerged pump 58 is also provided with a pivotably mounted float 62 to sense the water level within the tank 27; other conventional liquid level sensors may be substituted therefore. The submerged pump 58 supplies water through a watertight brass connector 63 in the barrier wall 54 for further treatment by apparatus located in the dry chamber 53.

In the dry chamber 53, water from the tank 27 is piped into and out of an activated carbon water filter 64 of conventional form, to remove potentially harmful dissolved and suspended impurities. The water filter 64 shown is known as a "whole house" filter, being sized to treat an entire domestic water supply, in place of individual filters associated with particular appliances, for example. The preferred filter medium is currently activated carbon treated with silver compounds, although other microporous solid organic or inorganic filter media may also be of use, such as suitably doped zeolites. From the water filter 64, the water is piped via a differential pressure control unit 65

(functions described below) to an ultraviolet treatment unit 66, in which it is irradiated with intense ultraviolet light to kill bacteria and other micro-organisms therein. From the ultraviolet treatment unit 66, the water is pumped back tlirough a brass connector 63 in the barrier wall 54 and a non-return valve 67 to an outlet 68 of the integrated unit 50.

The dry chamber 53 of the integrated unit 51 also contains a UN controller unit 69 for the ultraviolet treatment unit 66, a power supply 70 and a programmable logic controller (PLC) 71. The power supply 70 includes a transformer to convert mains alternating current to direct current at a suitable voltage for any component of the integrated unit 51 requiring it. The PLC 71 is in overall control of the operation of both the integrated unit 51 and a remainder the water supply system of which it forms a part, as described below. (Note: electrical connections have been omitted from the Figures for clarity).

In operation, rainwater is collected, filtered through the fine filtration unit 26 and stored in the tanlc 27, generally as described above. If the supply of rainwater exceeds demand, excess rainwater can be released from the tank 27 via an overflow 72 leading to an existing drain or to a soakaway. Alternatively, excess rainwater can be diverted before it reaches the tank 27 (see above).

The differential pressure control unit 65 is connected to pressure and/or flow sensors located in the water supply system of the premises supplied. When water is taken from the system (e.g. a tap is opened or a cistern is flushed) the differential pressure control unit 65 registers this and activates the submerged pump 58. Water is then pumped from the tanlc 27, through the water filter 64 and the UN treatment unit 66 to the premises supplied. When demand ceases, the control unit 65 turns the pump 58 off again.

Conventionally, these pressure and/or flow sensors would comprise pressure-sensing diaphragm valves and/or in-line flow switches, located upstream and downstream of the unit 51. However, such electromechanical devices tend to be expensive and sophisticated, possibly leading to reliability problems.

An alternative, less complex, approach would be to monitor the pressure drop across a single flow restricting device, such as a solenoid valve or an orifice plate mounted downstream of the unit 51. As soon as water is taken from downstream of this restrictor, a pressure differential will be established across it, which will be detected and a signal sent to turn on the pump 58 in the tank 27. Once the offtake of water is complete, the pressure differential will disappear, and the pump 58 is stopped.

Another approach is to insert a Pelton wheel arrangement with a rotary motion sensor into the water supply piping downstream of the unit 51, optionally with a venturi to direct water on to its cups. Taking water from the piping will lead to a flow of water turning the Pelton wheel. In one embodiment, any rotation of the Pelton wheel produces a signal to turn on the pump 58. In another, a threshold rotation rate is set for the Pelton wheel, above which the pump 58 operates but below which it stops.

The differential pressure control unit 65, PLC 71 and UV controller unit 69 are linked to ensure that the UN treatment unit 66 operates only when water is being passed therethrough. Sources, for such UN treatment units 66 may occasionally fail. As the sterilisation effect of the UN treatment is essential to ensure that water from the integrated unit 51 is of potable quality, the PLC 71 monitors the current drain by the UV controller unit 69. Should this drop, indicating UN source failure, the PLC 71 cuts power to the submerged pump 58 so that no untreated water is supplied. A signal is sent by cable or radio to a display unit within the premises supplied, to indicate that the UN source must be replaced before the rainwater supply system can be used once more. Similar signals can be sent in case of pump 58 failure or the like.

Should the level sensor float 62 indicate that the water level in the tanlc 27 has fallen so low that the intake unit 61 would be close to the floor of the tank 27, and so might be taking in undesirable material from near the floor, the PLC 71 will switch off the pump 58.

The operation of the integrated unit 51 in these circumstances will depend on exactly how the rainwater supply system, the conventional mains water supply and the water system within the premises are connected. There are several alternatives.

Firstly, the outlet 68 of the integrated unit 51 and the conventional rising main of the mains water supply can be connected to the premises water system as alternative sources. A solenoid non-return valve, controlled by the PLC 71, closes the rising main whilst there is sufficient rainwater in the tanlc 27 to supply the premises water system. When rainwater runs short, and the PLC shuts off the submerged pump 58 the solenoid valve is opened and the premises are supplied with water direct from the mains until enough fresh rainwater has collected for the rainwater supply system to operate once more. Alternatively, in a preferred arrangement, the rising main is instead connected to the rainwater tank 27, via a solenoid valve and a conventional tundish valve. A tundish valve, in which water is projected from a nozzle obliquely into a conical receiver, ensures that the water is well oxygenated, preventing it becoming stagnant in the tank 27. It also acts as a non-return valve. UK regulations specify that a tundish valve must be mounted at least

150mm above the device that it feeds (here the tanlc 27), ideally between 150 and 300mm thereabove. The underground location of the integrated unit 51 and tank 27 make this simple to arrange, and the tundish valve can deliver mains water straight to the fine filtration unit 26 through the same inlet 31 as is used for collected rainwater. Thus, when the water level in the tank 27 falls too low, the PLC 71 opens the solenoid valve on the rising main, and oxygenated mains water is delivered to top-up the water in the tank 27 until an inflow of collected rainwater is re-established.

As a third option, the rising main is connected both directly to the premises and via a tundish valve to the tank 27. When the water in the tanlc 27 runs low, the PLC 71 opens a solenoid valve in the rising main. The premises are supplied directly with mains water and simultaneously the tanlc 27 is topped-up. When the level of water in the tank 27 has reached a preselected level above the minimum at which the submerged pump 58 was turned off, the mains supply to the premises is cut off once more, and supply from the tank 27 is resumed. This avoids rapid on-off cycling of the pump 58 and the other components of the integrated unit 51, which might lead to early component failure.

Should there be a general power failure, preventing operation of the integrated unit 51, or should the pump 58 fail, preventing delivery of water from the tank 27, it will be necessary to revert to water from the rising main for all purposes. A connecting pipe therefore leads from the rising main to the piping connecting the integrated unit 51 and the premises to be supplied. A solenoid valve in this connecting pipe closes it under normal operating conditions. If the pump 58 fails, however, the PLC 71 allows this solenoid valve to open, allowing mains water to flow into the piping between the unit 51 and the premises. A nonreturn valve prevents this water from flowing to the unit 51 and the tanlc 27. Another nonreturn valve is sited in the connecting pipe to prevent water flowing back into the rising main.

In the event of a power failure, the solenoid valve in the connecting pipe is biased to fail open, again establishing a flow of mains water to the premises. When the power is restored, or the pump 58 is operating once more, the PLC 71 closes this solenoid and delivery to the premises of treated water from the tank 27 is resumed.

Since the embodiments of the system described above are largely dependent on a mains electricity supply, they may not be suitable for isolated locations. Also, it would be preferable to have a water supply that would continue to operate even when mains electricity has been interrupted. It is believed that regulations are proposed or already in force in some jurisdictions bamiing water supply systems that would fail along with the mains electricity supply.

For such situations, it is envisaged that electrical accumulators would be provided, to build up a reserve of energy that would allow prolonged operation of the system in the absence of a mains power supply. As Figure 7 shows, there is a space above the tank 27, to one side or another of the inspection chamber 28, where a bank of lead-acid batteries or other accumulators could conveniently be located. These could be trickle-charged from the mains power supply to keep them fully topped up until they are needed. Instead of relying on the mains power supply, the systems described could also be powered by solar panels or wind power, in each case using a bank of electrical accumulators to store power. The solar panels could be mounted to an appropriately aligned house wall or fence, but it would be particularly convenient if they were mounted above the tanlc 27, either on or next to the inspection hatch 35. Such an arrangement would be particularly useful in regions of the world without either mains water or mains electricity supplies.

The system described, comprising the integrated unit 51 and tank 27 located in a common underground chamber, may also be used in conjunction with a spring or borehole water supply, as well as with a rainwater collection system as described.

An alternative form of integrated unit 73 is shown in Figure 14. This is substantially identical to the integrated unit 51 of Figures 12 and 13, except that the "whole house" water filter 64, the UV treatment unit 66 and the UV controller unit 69 are omitted. Thus, water from the alternative integrated unit 73 will not have been purified to drinking water standards and can only be employed for non-potable uses, such as flushing toilets and the like (see above).

However, this integrated unit 73 does include the fine filtration unit 26, the differential pressure control unit 65 and the PLC 71 in a single conveniently installable and maintainable unit, bolted to the top of the underground storage tanlc 27. It is thus a significant improvement on current systems for supplying collected rainwater to a premises, which must be fitted piecemeal and require considerable ancillary work. A monitor unit may be provided to indicate to an occupant of the premises various data concerning the operation of either version of the integrated unit 51, 73. This monitor unit is situated within the premises, being connected to the unit 51, 73 by a multi-core cable. The unit is powered by a 12v dc supply, fed along the multi-core cable from the unit 51, 73. The unit provides information concerning the amount of water in the tank 27, and audible and visual alarms to alert the occupant in the event of a malfunction.

The volume of water held within the tank 27 is indicated by a vertical bar display made up of light emitting diodes (LEDs) or a liquid crystal display (LCD). To produce a linear volume scale, the monitor unit is provided with a chip programmed to convert a measured water level within the tanlc 27 to a water volume, talcing the shape of the particular tank 27 into account (most tanks are generally horizontally-aligned cylinders).

The monitor unit is also programmed to sound an audible alarm and illuminate a warning light in response to a range of different malfunctions. Ideally, a different audible alarm can be assigned to each type of malfunction. The monitor unit also has an alphanumeric display to indicate fault codes specific to each malfunction.

Four possible malfunctions that would need to be notified to the occupant as soon as possible are:

1. The water level sensor within the tanlc is not working correctly;

2. The pump in the tank is switched on, but no water is flowing out of the integrated unit (as indicated by a flow sensor located in the outlet therefrom); 3. The tank is empty, but no water is flowing into it (where the tank is provided with a top-up system from the mains);

4. The power to the pump has failed, or the unit is otherwise inoperative, but a replacement flow from the rising main has not been established.

Other malfunctions may be indicated if desired. Once a malfunction has been detected, the monitor unit stops monitoring for that particular malfunction, and continues to display the appropriate fault code, until it is instructed that the malfunction has been corrected.

The monitor unit has a memory in which is recorded the nature of any malfunction, together with the date and time at which it occurred. A serial data communications link is provided, so that maintenance and repair personnel can download these data to a hand-held computer or the like, for diagnostic purposes. It is envisaged that variants may be capable of transmitting such data remotely, for example via the Internet or wireless communication links.

With sufficient memory, a complete record can be kept of the history of the system, including data on its normal operation as well as on malfunctions.

The monitor unit also displays when a service visit is required, either to correct a fault or for routine maintenance. As part of a service visit, data such as the time and date, a recommended period before the next routine visit, and a contact telephone number can all be uploaded to the monitor unit via the serial communications link. If desired, further tallies and displays indicating the status of other components of the integrated unit may be added. However, in most cases, a simple "power on" LED will suffice.

Claims

1. A filter-separator device mountable to a rainwater disposal means of a building to divert rainwater therefrom for collection, said device comprising a hollow vessel open at an upper and a lower end and divided into an upper and a lower chamber by generally horizontal barrier means, outlet means from the upper chamber adjacent said barrier means and funnel means extending from above the outlet means within the upper chamber tlirough said barrier means to the lower chamber with an upper periphery of the funnel means extending towards the walls of the upper chamber to define a separation gap therebetween.

2. A device as claimed in claim 1, wherein said separation gap has a width of no more than two millimetres.

3. A device as claimed in claim 2, wherein said gap has a width of between one-tenth of a millimetre and one millimetre, optionally of approximately one half of a millimetre.

4. A device as claimed in any one of the preceding claims, wherein the outlet means is connected to rainwater collection means and the lower chamber is comiected to drainage means.

5. A device as claimed in any one of the preceding claims, wherein the funnel means comprises filter mesh means, such that water may also pass from an interior thereof towards the outlet means.

6. A device as claimed in any one of the preceding claims, further provided with means selectively to guide water away from said separation gap and towards the lower chamber, thereby substantially halting collection of rainwater.

7. A filtration separation device for rainwater comprising first chamber means provided with inlet means, second intermediate chamber means, and third chamber means provided with first outlet means for filtered water, filter mesh means between the second and third chamber means, and separation gap means connecting the first and second chamber means.

8. A device as claimed in claim 7, wherein the first chamber means is provided with means to divert water entering through the inlet means towards the separation gap means.

9. A device as claimed in either claim 7 or claim 8, wherein the first chamber means has second outlet means for water carrying solid material unable to pass through said separation gap means.

10. A device as claimed in any one of claims 7 to 9, wherein the filter mesh means comprises a mesh of metal, optionally stainless steel, having a nominal aperture size of no more than 200 micrometres, advantageously having a nominal aperture size of no more than 125 micrometres, optionally of no more than 20 micrometres, and in some cases, no more than 5 micrometres.

11. A device as claimed in any one of claims 7 to 10, wherein the filter mesh extends within and is so spaced from the walls of the second chamber means as to define the third chamber means within the second chamber means.

12. A device as claimed in any one of claims 7 to 11, wherein the separation gap means has a width of no more than two millimetres, advantageously of between one millimetre and one-tenth of a millimetre, and optionally of approximately one-half of a millimetre.

13. A device as claimed in any one of the preceding claims, further comprising means to store said rainwater for subsequent use and located, with said device, in a common subterranean cavity.

14. A device as claimed in any one of the preceding claims, further comprising a water storage tank, water supply means connectable to a premises to be supplied, pressure sensing means linked to said water supply means and control means therefore.

15. A device as claimed in claim 14, further comprising pump means within the storage tank and controllable by the control means to be operated when the pressure sensing means detects water being taken from the water supply means.

16. A device as claimed in either claim 14 or claim 15, further comprising means to sense the water level within the tanlc.

17. A device as claimed in any one of claims 14 to 16, further comprising means to monitor and display to a user operating data such as volume of water held within the tank and indications concerning any malfunctions which may occur.

18. A device as claimed in claim 17, wherein the monitoring and display means include memory means to store malfunction indications, including date and time indications, for subsequent use in the course of repair and maintenance work.

19. A filtration/separation device substantially as described herein with reference to the Figures of the accompanying drawings.