GB2480834A

GB2480834A - A building comprising a rainwater collection and storage apparatus

Info

Publication number: GB2480834A
Application number: GB1009236A
Authority: GB
Inventors: Kevin Woolass
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-06-02
Filing date: 2010-06-02
Publication date: 2011-12-07
Anticipated expiration: 2030-06-02
Also published as: GB201009236D0; GB2480834B

Abstract

The apparatus includes at least one elongate storage tank 104 positioned within a roof enclosure 103 of a building and configured to span at least three roof joists 112 so as to spread the load of the tank and the collected rainwater. Rainwater is supplied from the gutter 105 via a sump 106 below the gutter and a pump (500 figure 5) for subsequent supply to a toilet 110 within the building. Water level sensors (202 fibre 2), (506 figure 5) positioned within the storage tank and sump control the operation of the pump in response to the water level in the storage tank and sump. Filters (504 figure 5) filter the rainwater from the gutter to the pump. The tank preferably has a circular cross section and may be supported by the joists or suspended by cables.

Description

RAINWATER COLLECTION AND STORAGE

The present invention relates to a building comprising means for rainwater collection and storage within a roof enclosure region of the building.

In response to an increasing global population, limited resources and a desire generally for countries and communities to adopt more efficient use of energy and natural resources, rainwater harvesting systems have been proposed for both commercial and domestic buildings.

These rainwater management systems typically harvest rainwater collected from the gutter for storage and subsequent use by utilities within the building to reduce the demand for mains water. Furthermore, harvesting rainwater reduces the demand on the main drain into which surface water is fed and where a building does not have appropriate surface water drainage, to reduce the amount of surface water that must soak-away' from the building following heavy rainfall.

Example rainwater collection and storage systems can be found in GB 2344132, GB 2439737, GB 2449534, GB 2457695, and GB 2463990.

However, these conventional systems are disadvantageous for a number of reasons. One primary barrier to widespread implementation of environmentally friendly rainwater harvesting systems is the complexity of instillation, either to a new build or an existing building including in particular the additional structural demand placed on the building to accommodate safely heavy and bulky water storage tanks. Additionally, some conventional systems involve transferring the rainwater collected at the gutter over large vertical distances for storage and/or use that requires excessive pumping, which in turn is energy inefficient.

There is therefore a need for more efficient rainwater collection and storage apparatus that may be conveniently installed within a building without substantial modification to the building in order to install and accommodate securely the apparatus.

Accordingly, the present invention provides a building configured with an energy efficient rainwater collection and storage apparatus having elongate water storage tanks that may be conveniently housed within the region of the roof and designed to distribute the weight of the storage tank and stored water. The present invention, whilst utilising one or more water pumps, is configured to minimise the head' height of the system to reduce the distance, in the vertical direction by which rainwater is transferred from the region of the gutter to the roof storage tank.

According to a first aspect of the present invention there is provided a building comprising: a roof, walls, a roof enclosure defined by the roof and a floor extending between the walls and below the roof the floor comprising a plurality of roofjoists; a gutter to collect rainwater from the roof, a sump positioned below a level of the gutter to collect rainwater from the gutter; at least one elongate water storage tank extending within the roof enclosure and having a length sufficient to span at least three roofjoists to spread the loading force of the storage tank when containing water; a pump to transfer rainwater from the sump to the storage tank; a filter to filter rainwater received by the pump from the gutter; a first water level sensor positioned at the storage tank and a second water level sensor positioned at the sump, the first and second sensors coupled together and/or to the pump electronically so as to control operation of the pump in response to a respective predetermined water level within the storage tank and the sump; at least one input conduit connecting the sump and the storage tank to allow rainwater to be transferred from the sump to the storage tank; and at least one output conduit connecting the storage tank to at least one toilet within the building to allow water to be transferred from the storage tank to the toilet.

Preferably, the water storage tank spans at least four, five, six, seven or more joists.

Preferably, the storage tank is supported by the joists. Alternatively, the water storage tank is supported by cables and/or rigid support members, for example metal, wood or plastic struts extending from an upper region of the roof enclosure. Preferably, the water storage tank comprises a circular cross section. Optionally, a mains water input conduit is connected to the tank to allow mains water to be fed into the storage tank.

Within the specification, reference to roofjoists includes any elongate beam that extends between the walls of the building and configured to support the roof and/or upper floor of the building to define the roof enclosure below the roof These roofjoists are aligned parallel with one another and typically extend between lintels or suitable supporting structures at the upper region of the house walls. The spacing between roofjoists is determined by the distance over which the joists extend between the walls, the material of the joists and the physical dimensions of the joist including in particular the cross sectional area and cross sectional shape. The elongate storage tank of the present invention, when assembled in a use configuration has an elongate length that is sufficient to span at least three joists. That is, when configured to sit onto top of the joists, the elongate tank would be positioned in contact with at least three joists and extend over the intermediate space between all three joists. However, according to the present invention, the elongate tank is not necessarily aligned perpendicular to the joists and may be aligned parallel or transverse to the joists. Moreover, the elongate storage tank may not be supported by the joists directly and instead may be suspended by cables or rigid support struts, for example from the roof trusses so as to be not in contact with the roofjoists. However, the length of the storage tank is such that the loading forces exerted by the tank and the stored water are distributed over a single joist (when aligned parallel to the joists) or more preferably, two, three, four or more joists when aligned transverse to the roofjoists. However, and preferably, the elongate storage tank is aligned perpendicular to the roofjoists.

Where the elongate storage tank is bent round to form two or more parallel lengths, cormected by a U-bend, the length of the storage tank comprises the length from or including one end to the U-bend section.

Preferably, the first and second sensors comprise float mechanisms, the movement of which is responsive to the level of water within the respective storage tank and sump.

Optionally, the sump sensor is integral to the pump and is implemented as an electronic sensor or a mechanical actuator. Optionally, the first sensor positioned at the storage tank is implemented as an electronic sensor to determine the water level and volume within the storage tank. Preferably, the pump is positioned at the sump. Preferably, a further filter is positioned at the storage tank. Preferably the water storage tank is enclosed and comprises at least one breather vent open to the surrounding air. Preferably, a control tank is coupled to the elongate storage tank, the control tank comprising the first sensor and receiving the input conduit connecting the sump to the storage tank, the control tank being in fluid communication with the elongate storage tank. Preferably, the control tank further comprises an overflow conduit extending from the control tank to a region outside the roof enclosure. The overflow conduit also acts as a breather tube for the storage tank.

Preferably, a further breather vent is provided at one end of the elongate storage tank furthest from the control tank. Optionally, breather vents are provided along the length of the elongate storage tank.

Preferably the diameter of the elongate water tank is in the range 50 mm to 500 mm or more preferably 100 mm to 300 mm.

Preferably the vertical height difference between the sump and the storage tank is in the range 0 mm to 2000 mm and more preferably 200 mm to 1000 mm. Preferably, the elongate water storage tank comprises at least one depression region relative to the horizontal to provide water collection zones at the depression regions. Preferably at least one flow or volume meter is provided to monitor a volume of water transferred from the storage tank to the at least one toilet.

According to a specific implementation, the building may comprise two or more storage tanks, each being supplied by a sump and a pump. Each storage tank is interconnected via a connecting conduit in fluid communication. This type of coupled arrangement of storage tanks would comprise a single control tank having a sensor and mains water input conduit.

Alternatively, the mains water could be fed to each of the storage tanks, each comprising a suitable sensor to determine the water level and to activate independently pumps to supply water from sumps respectively positioned at different gutter positions.

According to further embodiments, the present apparatus may comprise a plurality of sumps positioned at different regions along the gutter and a plurality of pumps, each pump configured to supply rainwater collected at each sump into one or more elongate storage tanks within the roof enclosure.

A specific implementation of the specific implementation of the present invention will now be described, by way of example only and with reference to the accompanying drawings in which: figure 1 is a schematic side elevation view of a building having a rainwater collection and storage apparatus according to a specific implementation of the present invention; figure 2 is a schematic cross sectional side elevation view at the roof region of the building of figure 1; figure 3 is a schematic plan view of the elongate storage tank positioned within the roof enclosure of figure 2; figure 4 is a schematic side elevation view of the elongate storage tank of figure 3; figure 5 is a schematic cross sectional side elevation view of a section of gutter and sump detailed at figures 1 and 2; figure 6a is a cross sectional end view of the gutter and sump of figure 5; figure 6b is a cross sectional end view of the gutter, downpipe and a downpipe extension according to a specific implementation of the present invention; and figure 6c is a plan view of the gutter, downpipe and downpipe extension of figure 6b.

Referring to figure 1, building 100 includes walls 101, roof 102 and a roof enclosure 103 closed at its lowermost end by floor 113 extending between walls 101. Floor 113 is formed, at least partially, by a plurality ofjoists or support beams 112 also extending between walls 101. A gutter 105 extends around the lowermost perimeter of roof 102 so as to collect run-off rainwater received from roof 102. An elongate rainwater storage tank 104 is positioned perpendicular to the joists 112 within roof enclosure 103 and extends at least half the distance between walls 101 in a substantially horizontal plane. Storage tank 104 is configured to store a volume of collected rainwater 109 with the load being supported joists 112.

At least one sump 106 is positioned below gutter 105 and in fluid communication therewith so as to receive the collected rainwater from roof 102. A rainwater transfer conduit 107 provides fluid communication between sump 106 and storage tank 104. A control tank 111 is positioned at one end of the elongate storage tank 104 in close proximity to sump 106, and is configured to receive the supply conduit 107 and house additional sensor and float arrangements illustrated with reference to figures 2 to 4.

An output conduit 108 extends from storage tank 104 into the main occupancy area 114 of building 100. According to specific embodiments, conduit 108 may extend within the cavity wall region (not shown) of building 100. Conduit 108 provides fluid communication between storage tank 104 enabling supply to toilets 110.

Referring to figure 2, control tank 111 comprises a substantially cuboid configuration and is provided in fluid communication with the elongate storage tank 104 configured to store the main body of collected rainwater 109. Tank 104 comprises a substantially cylindrical cross section being appropriately sized to enable convenient installation within the roof enclosure 103, for example via a loft hatch or attic stairwell. Alternatively, the elongate storage tank may be installed by removing one or more roof tiles so as to gain access through the roof. Accordingly, tank 104 may be divided into coimectable sections 104a, 104b, 104c and 104d referring to figure 3. Each section 104 may be supported directed upon joists 112 or preferably via intermediate mountings 206 to ensure tank 104 remains stably mounted when in use. According to further embodiments, tank 104 may be suspended above joists 112 via suitable mounting cables (not shown) extending from transverse roof struts 208 or diagonal roof struts 210.

Control tank 111 houses a first float mechanism 200, configured such that movement of the float by the rising water level within tank 111 provides an electronic output signal coupled directly or indirectly to pump 500 mounted at sump 106 referring to figure 5.

Alternatively, a mechanical or electronic signal from sensor arrangement 200 may be supplied or communicated to a control flow valve configured to regulate the flow of water transferred from sump 106 to tank 111.

Similarly, tank ill accommodates a mains water float arrangement 202 also responsive to the water level within tank 111 and 104. Mains float arrangement 202 is also configured to output an electronic signal and/or to regulate mechanically a control valve positioned at a mains water supply conduit 209 configured to supply mains water from the mains water supplytotanklil.

A suitable overflow conduit 205 extends from tank 111 and out of the roof enclosure 103 so as to provide a safety overflow in the event of a failure of float mechanism 200.

Elongate tank 104 and control tank 111 are substantially sealed vessels and are open to the surrounding air via a breather conduit 203 extending from supply conduit 107. Breather conduit 203 extends from the highest point of supply conduit 107 so as to avoid a reverse siphon effect' that would otherwise occur when the pump is deactivated and the water level within tank 111 is sufficiently high so as to submerge the output end of the supply conduit 107. The elongate storage tank 104 and control tank 111 are also vented via overflow conduit 205 and a further vent 300 (referring to figure 3) positioned at a region of the elongate storage tank 104 furthest from control tank 111. According to a further embodiment, tank 104 is devoid of additional vent 300 and re-enters control tank 111 so as to form a loop arrangement with both ends of the elongate tank 104 connected in fluid communication via the control tank 111. Supply conduit 107 enters control tank 111 via conduit extension 204 that terminates within tank 111 at a particulate filter 201.

Collected rainwater 109 within elongate tank 104 is connected in fluid communication with toilets 110 within building 100 via output conduit 108 that connects to the lowermost region of tank 104 via downpipe 207. For convenience and to minimise disruption during installation, mains supply conduit 209 may be routed through the cavity wall region of the building 100 at the same place as the supply conduit 108.

According to a further embodiment, the building 100 may comprise two or more water collection storage apparatus as depicted in figure 2, with each control tank 111 interconnected by conduit section 211. That is, each collection apparatus comprises the modular elongate storage tank 104, a control tank 111, supply conduit 107, sump 106 and associated pump. However, the second collection apparatus, at control tank 111 may not comprise a separate mains water input conduit 209 and/or sensor arrangement 200.

Referring to figure 3, elongate storage tank 104 is configured to extend over the majority of the floor space between the roof enclosure 103 and to span a maximum and optimum number ofjoists 1 12a, 1 12b, 1 12c, 1 12d and 1 12e so as to maximise distribution of the loading force created by tank 104 and stored water 109. In particular, tank 104 extending perpendicular or transverse to joists 112 is modular in construction and comprises a bent U-bend section 1 04b such that tank 104 bends back on itself so as to provide at least two parallel sections 104a, 104d positioned side-by-side in the horizontal plane above joists 112. The length of tank 104 may therefore be defined as the distance between control tank 111 and U-bend section 104b. Accordingly, the weight of the stored water 109 is distributed across the plurality ofjoists 1 12a to 112e and along the length of each joist as the tank 104 bends back on itself and comprises parallel runs.

Control tank 111 is supported upon a support platform 302 extending between joists 112a and 112b. Alternatively, control tank 111 may be suspended by the same cabling or rigid support struts (not shown) to support the elongate tank 104 according to the further embodiment.

Referring to figure 4, the elongate tank sections 104 are declined relative to the horizontal so as to provide a depression region along the length of tank 104. Accordingly, when the level of water 109 within tank 104 is low, the depression regions ensure that any remaining water drains to the lowest point provided at junction 301 between the interconnected tank sections 104c and 104d. Downpipe 207 extends from the lowermost region ofjunction 302 to couple in fluid communication tank 104 with output conduit 108 supplying toilets 110.

Water 109 collected at the depression region of tank 104 acts as a reserve, or surplus water volume, in the event of a minimum water level within the storage tank immediately prior to refilling by the mains water supply (in the event of an absence of rainfall over a long period). Accordingly, if water is demanded from the storage system via toilet flushing, there is sufficient surplus water 109 to ensure water is supplied immediately before and during water top-up' via the mains water supply. This reserve 109, provided by the downward-angled interconnection of elongate storage tank segments 1 04c and 1 04d, ensures water is supplied during the time taken to refill the system with mains water.

Water level sensor mechanism 202 comprises a buoyancy float 301 having a substantially cuboidal configuration with a substantially planar surface in contact with the water level.

Float 301 is configured to be entirely submerged by the water within control tank 111 such that additional water collected within tank 111 does not increase the force exerted by float ion a seal mechanism (not shown) at tank ill. Such a force would otherwise compromise the seal mechanism and reduce its longevity. Moreover, the volume of float 301 that is submerged within water 109 is minimised so as to increase the sensitivity of the sensor mechanism 202. This cuboidal float arrangement may be provided at all water level float monitoring system 200, 202 and 506 referring to figures 2 to 5.

The elongate storage tank section 104 extends from control tank lii a distance 401 above the base or floor 402 of the control tank iii. Accordingly, any sediment within the water of control tank 111 settles to the bottom of this tank and is not allowed to flow into the elongate storage tank 104. That is, the entry port or communication between control tank 111 and elongate tank 104 is at a predetermined height above the level of the floor 402 of tank iii.

Referring to figures 5 and 6a to 6c, sump 106 comprises a substantially square cross-section and extends along the underside of a section of gutter 105 positioned to receive water from roof 102. In particular, gutter 105 is modified by formation of an elongate slot 507 formed in the gutter floor such that water within gutter 105 drains under gravity into sump 106.

A filter medium 504 is housed within sump 106 which is divided into a first compartment 501, housing pump 500 and a second compartment 502 housing a float mechanism 506, 509. Filter medium 504 comprises any conventional particulate or fibrous filler to inhibit particulate matter from passing into the pump body and in particular the perforated inlet tube 505.

Float compartment 502 is provided in fluid communication with the pump compartment 501 via one or a plurality of apertures formed within a partition wall 503. Float 506 is moveably housed within compartment 502 and is response to the water level as water flows into the compartment from the pump compartment 501. A flap 510 is positioned directly above the float compartment 501 and is hingeably mounted at pivot 511. Water within gutter 105 is capable of flowing under and around flap 510 and into float compartment 502 via aperture 508. However, the main supply route for rainwater into compartment 502 is via sump compartment 501 and the aperture(s) within partition wall 503. Movement of float 506 is output via suitable electrics 509 that are coupled to pump 500 so as to provide operational control of the pump to supply water to the control tank 111. That is, in use pump 500 is operable only when there is sufficient water within sump 106 as detected by float arrangement 506, 509. Similarly, pump 500 is inoperative to supply water to control tank 111 when there is sufficient water within tank 104, this being determined by float mechanism 200 which is also coupled to pump 500 and/or float arrangement 506, 509. By separating the sump into the first and second compartments 501, 502 and interconnecting them by partition wall 503, the sump arrangement ensures that the pump is activated only when there is sufficient water collected within the sump. That is, the compartment arrangement provides a mechanical time delay to ensure the pump is submerged before the float mechanism 506 is actuated by the rising water level. According to further specific implementations, the invention comprises a plurality of sumps, each having a dedicated operational pump and sensor arrangement implemented electronically or mechanically.

Referring to figures 6a to 6c gutter 105 also comprises a downpipe extension 513 having a cross sectional profile corresponding to that of downpipe 512 that is positioned in fluid communication with gutter 105. Downpipe extension 513 comprises a slightly smaller cross sectional width than downpipe 512 so as to slot within downpipe 512. The extension 513 may be secured in position by suitable screws or other means provided through the lower region of extension 513 and upper region of downpipe 512. Alternatively, a locating flange or collar (not shown) may be provided at the perimeter of downpipe extension 513 so as to seat the extension 513 within the upper region of downpipe 512 so as to extend from the base region of gutter 105. That is, downpipe extension 513 projects upwardly from downpipe 512 into the region defined by gutter 105 and is sealed at the interface region between downpipe 512 and gutter 105. A length of extension 516 extends into downpipe 512 so as to hold extension 513 in position and ensure water does not flow over the external surface of downpipe 512.

Downpipe extension 513 is configured so as to provide a conduit 600 through which rainwater within gutter 105 may flow into downpipe 512. Accordingly, water is prevented from flowing into the upper region of downpipe 512 directly by extension 513. The water level 514 is therefore configured to rise along the length of downpipe extension 513 to an uppermost open end 515. Only when the water level 514 rises to a height at and above the height by which the upper end 515 of extension 513 projects above the gutter base 105 will the collected rainwater flow into the downpipe 512. This increased volume of water within the gutter 105 is therefore available for transfer to the storage tank 104 within the roof enclosure 103 via sump 106 and pump 500.

In use, surface water from roof 102 is collected within gutter 105 which drains into sump 106. If there is capacity to receive water within tank 104 and tank 111, as determined by the water level monitor 200 within tank 111, pump 500 is maintained in a passive active state via an electronic couple between component 200 and the pump 500. However, water is only pumped from sump 106 to control tank 111 via conduit 107 if a sufficient water level is detected within sump 106 by float arrangement 506, 509 that is operable to activate pump 500 following displacement of float 506.

In particular, water level monitor 200 may be regarded as the master control and is configured to supply power to the water level monitor 506, 509 positioned at the sump 106 only in response to the detection of insufficient water within the elongate storage tank 104.

The secondary water level monitor 506, 509 is then configured to provide power to the pump 500 only if there is sufficient water detected within compartment 502 and 501. That is, pump 500 is activated only when there is output power from the master and secondary water level monitors 200 and 506, 509 respectively.

Water is then fed into tank 111 via second filter 201, also configured to remove any fine particulate matter. The collected water then flows from control tank 111 into elongate storage tank 104 ready for supply to toilets 110. If tank 104 and 111 are filled to capacity, water level monitor 200 deactivates pump 500 via an override control of float arrangement 506, 509 within sump 106. Similarly, if the water level within control tank 111 and elongate tank 104 drops below a predetermined level, float arrangement 202, 301 are configured to operate a control valve at mains water supply conduit 209 to supply mains water into tanks ill and 104.

In order to monitor a volume of water supplied from tanks 104 to toilet 110, a suitable water rate or flow monitor 400 is coupled at conduit 108. Further gauges may also be coupled to various different regions of the apparatus so as to monitor a volume of water supplied to tanks 111, 104 from the one or plurality of sumps 106 positioned around the gutter 105 of building 100. This way, it is possible to calculate the volume of mains water used and the volume of collected rainwater used.

According to a further implementation, control tank 111 may be configured to accommodate means to chemically treat the water 109 within tanks 104, 111. For example, an interchangeable container may be housed within tank 111 to house purification or coloration tablets and the like.

Claims

Claims: 1. A building comprising: a roof, walls, a roof enclosure defined by the roof and a floor extending between the walls and below the roof, the floor comprising a plurality of roofjoists; a gutter to collect rainwater from the roof; a sump positioned below a level of the gutter to collect rainwater from the gutter; at least one elongate water storage tank extending within the roof enclosure and having a length sufficient to span at least three roofjoists so as to spread the loading force of the storage tank when containing water; a pump to transfer rainwater from the sump to the storage tank; a filter to filter rainwater received by the pump from the gutter; a first water level sensor positioned at the storage tank and a second water level sensor positioned at the sump, the first and second sensors coupled together and/or to the pump electronically so as to control operation of the pump in response to a respective predetermined water level within the storage tank and the sump; at least one input conduit connecting the sump and the storage tank to allow rainwater to be transferred from the sump to the storage tank; and at least one output conduit connecting the storage tank to at least one toilet within the building to allow water to be transferred from the storage tank to the toilet.
2. The building as claimed in claim 1 wherein the elongate storage tank spans at least four joists.
3. The building as claimed in claims 1 or 2 wherein the storage tank is supported by the joists.
4. The building as claimed in claims 1 or 2 wherein the storage tank is supported by cables extending from an upper region of the roof enclosure.
5. The building as claimed in any preceding claim wherein the storage tank comprises a circular cross section.
6. The building as claimed in any preceding claim further comprising a mains water input conduit connected to the tank to allow mains water to be fed into the storage tank.
7. The building as claimed in any preceding claim wherein the first and second sensors comprise float mechanisms, the movement of which is responsive to the level of water within the respective storage tank and sump.
8. The building as claimed in any preceding claim wherein the pump is positioned at the sump.
9. The building as claimed in any preceding claim further comprising a filter positioned at the storage tank.
10. The building as claimed in any preceding claim wherein the storage tank is enclosed and comprises a breather vent open to the surrounding air.
11. The building as claimed in any preceding claim comprising a control tank coupled to the elongate storage tank, the control tank comprising the first sensor and receiving the input conduit connecting the sump to the storage tank, the control tank in fluid communication with the elongate storage tank.
12. The building as claimed in claim 5 wherein the diameter of the elongate tank is in the range 50 mm to 500 mm.
13. The building as claimed in claim 5 wherein the diameter of the storage tank is in the range 100 mm to 300 mm.
14. The building as claimed in any preceding claim wherein a vertical height difference between the sump and the storage tank is in the range 0 mm to 2000 mm.
15. The building as claimed in any preceding claim wherein a vertical height difference between the sump and the storage tank is in the range 200 mm to 1000 mm.
16. The building as claimed in any proceeding claim wherein the elongate storage tank comprises at least one depression region relative to the horizontal to provide water collection zones at the depression region.
17. The building as claimed in any preceding claim comprising at least one flow or volume meter to monitor a volume of water transferred from the storage tank to the at least one toilet.Amendments to the claims have been filed as follows.Claims: 1. A building comprising: a roof, walls, a roof enclosure defined by the roof and a floor extending between the walls and below the roof, the floor comprising a plurality of roofjoists; a gutter to collect rainwater from the roof; an elongate sump positioned below a level of the gutter and extending along the underside of the gutter to collect rainwater from the gutter; at least one elongate water storage tank extending within the roof enclosure and having a length sufficient to span and be supported by at least three roofjoists so as to spread the loading force of the storage tank when containing water; a pump to transfer rainwater from the sump to the storage tank; a first water level sensor positioned at the storage tank and a second water level sensor positioned at the sump, the first and second sensors coupled together and/or to the pump electronically so as to control operation of the pump in response to a respective 0) predetermined water level within the storage tank and the sump; Q at least one input conduit connecting the sump and the storage tank to allow Q rainwater to be transferred from the sump to the storage tank; and CO at least one output conduit connecting the storage tank to at least one toilet within the building to allow water to be transferred from the storage tank to the toilet; wherein a vertical height difference between the sump and the storage tank is in the range 200 mm to 1000 mm.2. The building as claimed in claim 1 wherein the elongate storage tank spans at least four joists.3. The building as claimed in any preceding claim wherein the storage tank comprises a circular cross section.4. The building as claimed in any preceding claim further comprising a mains water input conduit connected to the tank to allow mains water to be fed into the storage tank.5. The building as claimed in any preceding claim wherein the first and second sensors comprise float mechanisms, the movement of which is responsive to the level of water within the respective storage tank and sump.6. The building as claimed in any preceding claim wherein the pump is positioned at the sump.7. The building as claimed in any preceding claim further comprising a filter positioned at the storage tank.8. The building as claimed in any preceding claim wherein the storage tank is enclosed and comprises a breather vent open to the surrounding air.9. The building as claimed in any preceding claim comprising a control tank coupled to the elongate storage tank, the control tank comprising the first sensor and receiving the Q input conduit cormecting the sump to the storage tank, the control tank in fluid communication with the elongate storage tank.10. The building as claimed in claim 3 wherein the diameter of the elongate tank is in the range 50 mm to 500 mm.11. The building as claimed in claim 3 wherein the diameter of the storage tank is in the range 100mm to 300 mm.12. The building as claimed in any proceeding claim wherein the elongate storage tank comprises at least one depression region relative to the horizontal to provide water collection zones at the depression region.13. The building as claimed in any preceding claim comprising at least one flow or volume meter to monitor a volume of water transferred from the storage tank to the at least one toilet.14. The building as claimed in any preceding claim further comprising a filter to filter rainwater received by the pump from the gutter. r r Ct)