GB2483716A

GB2483716A - Rainwater irrigation system

Info

Publication number: GB2483716A
Application number: GB1015699.0A
Authority: GB
Inventors: Kieran Joseph Mcdonagh
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-09-17
Filing date: 2010-09-17
Publication date: 2012-03-21
Anticipated expiration: 2030-09-17
Also published as: GB201015699D0; GB2483716B; GB201111667D0; WO2012035301A1; GB2483742B; EP2616596A1; GB2483742A

Abstract

A rainwater irrigation system comprises rainwater receiving means, in the form of a down-pipe 1 connected to a substantially horizontal rainwater distribution pipe 2, which has at least one rainwater distribution part 7; and an overflow which allows rainwater to flow out of the down-pipe 1 and/or rainwater distribution pipe 2 when the level of water is not substantially above the maximum height of the rainwater distribution pipe 2.The overflow may comprise at least one hole 9 in the distribution pipe or a diverter 4, valve or weir in the down-pipe. The sectional area of the distribution pipe may be greater than that of the down-pipe. The system may include a planting area which has a rainwater storage volume which maybe adjacent or below the planting area. The storage volume may comprise a comminuted material such as ground tyres. Also disclosed is a method of irrigation using the afore described system.

Description

I

Rainwater Irrigation The present invention relates to a rainwater irrigation system and a method of rainwater irrigation.

lrrigation of plants in gardens or public spaces, whether planted in beds or planters, using rainwater has been practiced for many years. Traditionally, rainwater falling on building roofs is collected and stored in containers such as water bulls for use, whether by watering can or hose, when required.

This has the advantage of conserving expensive mains water, which does not need to be used for watering the plants.

According to current building regulations, it is necessary, for the protection of foundations and ground water systems, to control the amount of rainwater collected from building roofs and fed into the ground or local drainage systems, according to tight controls. A water butt, if of sufficient volume, can help to meet these requirements.

US 5,533,303 discloses a rainwater irrigation system wherein water drained from a roof area is collected and fed into a conventional down-pipe and stored at a lower end of the down-pipe in a storage body of enlarged diameter which in many ways acts as a water bull, The storage body is connected permanently to an irrigation system comprising a horizontally extending perforated pipe which runs adjacent to the building.

Rainwater collected by the system is stored in the storage body and fed through the perforated distribution pipe to plants planted adjacent the building.

The system allows a certain amount of water to be collected and fed at a controlled rate to the plants. In this way, the plants can be suitably irrigated when it is raining and for a certain period afterwards as the stored water is gradually fed through the perforated pipe to the plants.

Overflow is provided in the enlarged diameter section of the down-pipe so that once the storage section is full, excess water can be drained away to other means, such as land drainage or mains drainage.

The present inventors have realised that the arrangement of US5,533,303 has some disadvantages.

in particular, the inventors have realised that storing the rainwater in an enlarged diameter portion at the bottom of the down-pipe means that a large and potentially heavy volume of water has to be supported, which requires particularly strong supports either on the building or on the ground adjacent the building. Further, the storage section has to be specially designed and constructed and standard components cannot be used.

The present inventors have realised that a substantially horizontally extending distribution pipe can provide a sufficient storage volume for the amount of water to be used in irrigating the plants. In this way, a separate storage section in the down-pipe is not required. Further, the present inventors have realised that an overflow can be provided for allowing rainwater to flow out of the down-pipe or the distribution pipe when the level of rainwater has reached a level which is at or about the maximum height of the rainwater distribution pipe.

In this way, build up of a substantial volume of water in the down-pipe can be prevented, so that the weight on the down-pipe never becomes excessive. Standard components can then be used for the down-pipe, resulting in simplicity of design and economies in construction.

It is also found that the head of water stored is always substantially the same, with relatively little variation, as the height of the overflow above the distribution pipe is not large. In this way, the watering rate for the plants is closely predictable and does not vary excessively according to the volume of water stored.

A further advantage of the present invention is that the force of water leaving the rainwater distribution pipe never exceeds a certain value, so that damage to plants can be avoided.

Accordingly, the present invention provides a rainwater irrigation system, comprising means for receiving rainwater from a roof surface, a substantially horizontal rainwater distribution pipe, having at least one rainwater distribution part, an overflow being provided for allowing rainwater to flow out of the rainwater receiving means or the rainwater distribution pipe when the level of rainwater is at a height which is not substantially above the maximum height of the rainwater distribution pipe.

Further, the present invention provides a method of rainwater irrigation, using the rainwater irrigation system of the invention.

Preferred and optional features of the invention will be described further below.

The overflow may be provided in any of: a. The rainwater receiving means, b. The rainwater distribution pipe, or c. Another body which is in fluid communication with the rainwater receiving means and/or rainwater distribution pipe.

The overflow is provided to allow rainwater to flow out of the rainwater receiving means; rainwater distribution pipe or other body when the level of rainwater is at a height which is not substantially above the maximum height of the rainwater distribution pipe, preferably when the level of rainwater exceeds 10mm (and more preferably 5mm) above the maximum height of the rainwater distribution pipe.

The overflow may have any suitable form. For example, it may comprise an overflow hole whose lower edge is not substantially above the maximum height of the rainwater distribution pipe. The hole may be in communication with an overflow pipe.

The overflow may comprise a weir, the lowest point of the upper edge of which is at a height which is not substantially above the maximum height of the rainwater distribution pipe. The weir may communicate with an overflow pipe or duct.

The overflow pipe or duct may be provided to direct overflow water to: A soakaway A land drain A storm drain Mains drainage Water storage, for example a water butt or tank.

or any other suitable water disposal system.

The overflow rainwater may be retained by an infiltration system. The infiltration system suitably comprises a space filled with a granular material, such as sand or gravel or materials such as ground up lyre.

The overflow may, additionally or alternatively comprise a valve which is configured to open when the height of water exceeds a predetermined level, preferably 10mm above the maximum height of the rainwater distribution pipe. For example, the valve may be operated by the weight of water. It may be operated by a sensor which detects the level of water and which gives a signal if the level of water exceeds the predetermined level, the signal being configured to operate the valve. The valve may be operated by a float, such as a ball valve.

The overflow may be provided in, or in connection with the down-pipe. For example, it may comprise a diverter of a known type. Such diverters are known for use, for example with water butts, for allowing water to flow into a water butt until the water level in the water butt reaches a certain level after which water flows down a waste pipe.

The overflow may comprise a hole or weir formed in the rainwater distribution pipe.

There may be a plurality of overflows provided that the lowest is not substantially above the maximum height of the rainwater distribution pipe. For example, there may be a plurality of holes or weirs. In this way, each hole or weir can be made relatively small but the whole system will be able to cope with even quite large overflow volumes in case of storm showers.

The overflow may for example comprise at least one hole formed in the top portion of the rainwater distribution pipe, for example at or near the top of the rainwater distribution pipe.

The overflow may comprise at least one hole of diameter in the range 1cm -l0cms, more preferably in the range 2cms -Scms in the rainwater distribution pipe.

The means for receiving rainwater from a roof surface may be any conventional means. It is an advantage of the invention that commonly available materials can be used for the rainwater receiving means For example, rainwater may be collected by a system comprising any or all of gutters, rain hoppers or any other conventional means.

The rainwater is suitably collected in at least one down-pipe. The term down-pipe' as used herein indicates a pipe extending adjacent to a wall of a building, suitably substantially vertically, and fixed to the building at at least one point for delivering rainwater from the roof to the rainwater irrigation system. The rainwater receiving means may be of any suitable material, for example metal such as galvanised steel or synthetic material such as thermoplastic, for example UPVC, polyethylene or any other suitable material. It may comprise a tube or duct. The tube or duct may have any suitable cross section, for example round or square. It may have any suitable cross sectional area or dimension as are commonly used in the art for rainwater goods such as down-pipes. The rainwater receiving means preferably has a maximum outer dimension of at least 75mm, preferably at least 100mm. It is preferably no more than 200mm, preferably no more than 150mm.

The rainwater distribution pipe is substantially horizontal. There may be a slight fall in the rainwater distribution pipe from an end where it receives rainwater from the rainwater receiving means to a distal end, to assist with flow of water. The fall is preferably in the range of no more than 10mm per m.

Preferably, there is no section of enlarged cross-section in the down-pipe itself, though there may be an increase in cross-section between the down-pipe and the rainwater distribution pipe.

The rainwater distribution pipe may be formed of any suitable material, for example galvanised steel or synthetic material such as thermoplastic, for example UPVC or polyethylene. Preferably, it has an outer dimension of at least 75mm, preferably at least 100mm and more preferably at least 125mm. Preferably its maximum outer dimension does not exceed 300mm, being preferably not greater than 250mm The outer dimension in the range 100mm to 250mm is particularly suitable, as it gives a good balance of rainwater storage capacity, lack of visual intrusion and ability to distribute rainwater distribution over a sufficient distance.

The volume of the rainwater distribution pipe should be sufficient to accommodate a predetermined volume of rainwater. The predetermined volume of rainwater is preferably calculated in each case with reference to: a. Providing continuous irrigation of plants, for a predetermined period of time after rainfall has ceased at a predetermined rate of irrigation, and/or b. The capacity to contain a certain amount of rainwater, having reference to expected seasonal rainwater volumes for the location at which the system is used and with reference to building regulations limiting the volume of rainwater which may be discharged to the ground or local drainage systems.

The rainwater distribution pipe may have any suitable cross sectional shape for example circular or square. The aspect ratio, defined as the ratio of the cross sectional shape between the greatest dimension and the least dimension, is preferably in the range 0.5-2, more preferably in the range 1.5-0.75, and most preferably at or near unity. That is, the cross sectional shape is preferably a regular shape, as this gives low flow resistance.

The rainwater distribution pipe may also be formed of a flexible material, such as a hose, though in this case it is preferably supported so that it maintains a substantially horizontal configuration.

The rainwater receiving means can feed rainwater to the rainwater distribution pipe by

any suitable means.

There may be a conventional junction between the rainwater receiving means and the rainwater distribution pipe, for example an elbow junction or a T-junction or a diverter as described above, They may be connected by a short length of tubing for example a hose. It is preferred that the rainwater receiving means and the rainwater distribution pipe are connected by a connection in which there is substantially no narrowing, so that good flow is obtained.

In a preferred embodiment, a sectional area of the rainwater distribution pipe is greater than that of the rainwater receiving means, being for example at least 1.25 times the cross sectional area, more preferably at least 1.5 times the cross sectional area. This is found to give a good balance of flow properties and rainwater storage capacity.

The rainwater distribution pipe preferably has a closed end remote from the connection to the rainwater receiving means. For example, it may comprise an end cap of known type.

The rainwater distribution pipe is preferably mounted adjacent a building, for irrigating plants planted adjacent the building. Such plants typically are most at risk from water stress and the present invention provides a particularly reliable means of watering them. However, the rainwater distribution pipe could be placed in any suitable configuration, for example extending along a fence.

The rainwater distribution pipe may be supported by any suitable means. For example, it may rest upon the ground if the ground is substantially horizontal. However, it is preferably mounted on at least one support and preferably a plurality of supports. The skilled person will be able to determine the design of the supports for supporting the weight of the rainwater distribution pipe when it is full of water. The supports may be mounted on the ground or on the wall of a building or on a fence.

The rainwater distribution part may comprise any suitable means. For example, it may comprise at least one hole. Preferably, there are a plurality of rainwater distribution parts, for example a plurality of holes. The holes may be placed at regular intervals along the length of the distribution pipe. The holes may be selectively openable or closable so that certain areas do not receive rainwater irrigation (for example adjacent a manhole).

The rainwater distribution hole or holes suitably has a diameter in the range 1mm- 20mm, more preferably 2mm -10mm.

The rainwater distribution pipe may be continuous or it may be interrupted. If it is interrupted, sections may be joined by a syphon. For example, the rainwater distribution pipe may be broken adjacent a door, with a syphon pipe extending downwardly from a first section, below the level of the door sill and upwardly to join the second section of rainwater distribution pipe.

The rainwater distribution holes may be of any suitable size, to provide the desired rate of watering, taking into account the maximum head of water in the pipe! The rainwater distribution pipe may comprise at least one selectively operable tap or valve. The selectively operable tap or valve may be operated by hand or by mechanical means, such as an electric motor, which itself is selectively operable by a user or by a user-instructed programmable means.

In this way, water contained in the rainwater distribution pipe can be used for other purposes at the decision of a user, for example to water plants which are not adjacent to the rainwater distribution pipe. For example, a conventional water butt tap may be provided. It may be located in either the rainwater receiving means or the rainwater distribution pipe.

In practice, the rainwater distribution pipe of the present invention can act as: A water storage device, and/or, A device for directing irrigation to planted areas.

Preferably, the rainwater distribution pipe is configured to distribute rainwater over a substantial length, suitably in excess of Im, more preferably in excess of 2m and most preferably in excess of 3m. In this way, rainwater is distributed over a large area. This is beneficial compared to conventional rainwater absorption systems such as soak aways, which concentrate large amounts of water to a single location.

The rainwater distribution pipe may also be buried in soil.

A combination of different types of rainwater distribution part may be provided.

The rainwater irrigation system of the present invention may also include at least one planting area for receiving rainwater from the rainwater distribution pipe. The planting area is preferably adjacent a building. The planting area is advantageously below the rainwater distribution pipe.

Where a planting area is located adjacent to a building, the maximum quantity of rainwater that it can receive can be defined by local building regulations and the watering rate should be designed in accordance with these regulations.

The planting area may comprise an area in the ground or a separate planter or raised bed.

The planting area preferably comprises a first layer, comprising soil or planting medium into which plants are planted. Preferably, a rainwater storage volume is also provided adjacent to or below the planting area. The rainwater storage volume preferably comprises a packing material.

The packing material preferably comprises a material which, when packed, provides a permeable mass with a substantial hold-up volume for water. For example, it may be formed of crushed concrete, gravel, sand or any other suitable material, for example ground tyre material.

Alternatively, the rainwater storage volume may comprise baled tyres.

An impermeable barrier may be provided between a building wall and the planting layer and/or between the building wall and the rainwater storage volume to prevent rainwater damage to the wall.

The present invention will be further described by way of example only with reference to the accompanying drawings, in which:

Bilef Description of the Drawings

Figure 1 is a plan view of a first embodiment of a rainwater irrigation system according to the invention.

Figure 2 is an elevation view of the rainwater irrigation system of Figure 1.

Figure 3 is a plan view of a second embodiment of a rainwater irrigation system according to the present invention.

Figure 4 is an elevation view of the rainwater irrigation system of Figure 3.

Figure 5 is a sketch plan view of a building which includes a rainwater irrigation system according to the present invention.

Figure 6 is a sketch cross sectional view of planting areas for irrigation according to the present invention.

Detailed Description of the Drawings

Figure 1 shows a first embodiment of a rainwater irrigation system according to the invention. It comprises a rainwater receiving means in the form of a down-pipe I which receives rainwater from guttering and other conventional equipment on a roof (not shown). The down-pipe I is of conventional design.

The rainwater irrigation system further comprises a rainwater distribution pipe 2. It is formed of a substantially horizontally arranged plastic pipe of diameter 150mm which is mounted adjacent a wall, shown schematically cross hatched.

The down-pipe I and the rainwater distribution pipe 2 are connected by a T-Junction which is of a special design for increasing the cross sectional area from the down-pipe to the rainwater distribution pipe 2. The T-junction further includes a diverter 4. The diverter 4 comprises an upwardly directed truncated cone which is in fluid connection with a lower down-pipe 5. The lower down-pipe 5 is connected to means such as a conventional drain for disposing of overflow water. Any suitable means can be used for disposing of overflow water. The diverter comprises, at the top, slots 6. The lower position of the slots 6 defines the height at which overflow will commence. It can be seen that it is located just below (and no more than 10mm above) the maximum height of the rainwater distribution pipe 2, in accordance with the invention. As a result, the height of water in the down-pipe never becomes very large, so that large loads are not placed upon the down-pipe and so that the head of water in the rainwater distribution pipe does not become excessive. When the water level in the rainwater distribution pipe 2 reaches the level of the bottom ends of the slots 6, water starts to feed down into the lower down-pipe 5.

The rainwater distribution pipe comprises rainwater distribution holes 7. The holes 7 are shown arranged at regular intervals in the bottom portion of the pipe 2. Their diameter will be determined by the person skilled in the art to provide sufficient water rate for plants to be watered by the rainwater irrigation system and is suitably 2mm -10mm.

Brackets of conventional design 8 are provided for the down-pipe I and for the rainwater distribution pipe at regular intervals so that these can be supported on the wall 3.

A further overflow is provided by a series of larger diameter holes 9 which are formed adjacent the top of the rainwater distribution pipe 2. They are of diameter 1cm -10cm.

These provide another route for overflow water when the rainwater distribution pipe 2 becomes full. In particular, overflow water can be distributed evenly across a large area of soil, where it can be spread out and absorbed by the soil, so that efficient absorption of rainwater during storm conditions can be obtained, without overloading local drainage systems and providing a valuable delay to the flow of rainwater into local drainage systems, helping to avoid surge.

The rainwater distribution pipe is closed at its right hand end by an end cap 10.

Figure 3 shows another embodiment of rainwater irrigation system according to the invention. It comprises the same style of down-pipe 1 connected to a T-junction 3 incorporating a diverter 4 and a lower down-pipe 5 as shown in Figures 1 and 2.

However, in this case, the rainwater distribution pipe 12 is not provided with rainwater holes 7. instead, the rainwater distribution pipe acts as a rainwater storage device, rainwater being removed using a tap 13 in a manner similar to a conventional water butt.

However, overflow holes 9 are provided at the top in the same way as Figure 1.

Figure 5 is a sketch plan view of a building 14 which includes a number of rainwater irrigation units each comprising a rainwater irrigation system according to the invention.

They each comprise a down-pipe I for accepting water from guttering (not shown) which collects rainwater from the roof of the building 14. The down-pipe 1 is connected to a water distribution pipe 2, in each case, which is mounted adjacent a wall of the building 14 for irrigating with rainwater planting areas 15 which are shown cross hatched.

Any configuration of planting areas and associated rainwater irrigation systems may be used.

Figure 6 is a sketch cross section through a planting area used in connection with an irrigation system according to the present invention.

The down-pipe 1 and the distribution pipe 2 can be seen adjacent a wall, shown cross hatched. A planting area 15 is provided. Below the planting area there is a granular infiltration bed 16. This will be formed of granular material for example a no-fines granular material having aggregate size of lOmm-3Omm with a 30% minimum void ratio. It may comprise for example crushed concrete or baled tyres. This granular infiltration bed 16 can act as a rainwater storage volume.

If, in the case of a heavy storm, the amount of water delivered by the rainwater irrigation pipe 5 exceeds the storage capacity of the planting area 15, water will infiltrate into the infiltration bed 16. It can be stored there in the pores between the aggregate. This gives a useful rainwater storage volume which helps to absorb large quantities of rain in case of a storm, helping to meet requirements of local building regulations relating to the disposal of rainwater. A land drain (not shown) can be incorporated in the granular infiltration layer 16 if necessary. An impermeable membrane 17 is provided between the planted area 15, the granular infiltration bed 16 and the wall, to prevent damage to the foundations of the building 14. A layer of soft sand 18 is provided between the granular infiltration bed and the impermeable material to prevent damage to the latter.

The relative area, depth and accordingly volume of each of the planted areas 15 and the granular infiltration bed 16 can be balanced with the rainwater collection area of the building 14 and expected local rainwater levels to ensure that the amount of rainwater distributed into the adjacent soil 19 does not exceed local building regulations.

The present invention has been described above by way of example only and modifications can be made within the invention. The invention also extends to any generalisations of any of the features described herein or any combination of any such features or any generalisation of any such combination.

Claims

CLAIMS: 1. A rainwater irrigation system, comprising means for receiving rainwater from a roof surface, a substantially horizontal rainwater distribution pipe, having at least one rainwater distribution part, an overflow being provided for allowing rainwater to flow out of the rainwater receiving means or the rainwater distribution pipe when the level of rainwater is at a height which is not substantially above the maximum height of the rainwater distribution pipe.
2. A rainwater irrigation system according to claim 1, wherein the overflow is configured to allow rainwater to flow out of the rainwater receiving means or the rainwater distribution pipe when the level of rainwater exceeds 10mm above the maximum height of the rainwater distribution pipe.
3. A rainwater irrigation system according to claim 1 or 2, wherein the overflow comprises at least one overflow hole.
4. A rainwater irrigation system according to any preceding claim, wherein there is at least one overflow hole in the rainwater distribution pipe.
5. A rainwater irrigation system according to any preceding claim, wherein the overflow comprises at least one weir.
6. A rainwater irrigation system according to any preceding claim, wherein the overflow comprises at least one weir in the rainwater receiving means.
7. A rainwater irrigation system according to any preceding claim, wherein the overflow comprises a valve which is configured to open when the height of water exceeds a predetermined level which is not substantially above the maximum height of the rainwater distribution pipe.
8. A rainwater irrigation system according to any preceding claim, wherein the rainwater receiving means has a maximum outer dimension of at least 75mm, preferably at least 100mm.
9. A rainwater irrigation system according to any preceding claim, wherein the outer dimension of the rainwater receiving means is no more than 200mm, preferably no more than 150mm.
10. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution pipe has an outer dimension of at least 75mm, preferably at least 100mm and more preferably at least 125mm.
11. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution pipe has a maximum outer dimension which does not exceed 300mm, being preferably not greater than 250mm.
12. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution pipe has an outer dimension in the range 100mm to 250mm.
13. A rainwater irrigation system according to any preceding claim, wherein the rainwater receiving means and the rainwater distribution pipe are connected by at least one of an elbow junction, a T-junction or a diverter.
14. A rainwater irrigation system according to any preceding claim, wherein the rainwater receiving means and the rainwater distribution pipe are connected by a connection in which there is substantially no narrowing.
15. A rainwater irrigation system according to any preceding claim, wherein the sectional area of the rainwater distribution pipe is greater than that of the rainwater receiving means.
16. A rainwater irrigation system according to any preceding claim, wherein the sectional area of the rainwater distribution pipe is at least 1.25 times the cross sectional area, more preferably at least 1.5 times the cross sectional area of the rainwater receiving means.
17. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution device comprises at least one simple hole formed in the rainwater distribution pipe.
18. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution device comprises at least one tap.
19. A rainwater irrigation system according to any preceding claim, further comprising at least one planting area for receiving rainwater from the rainwater distribution pipe.
20. A rainwater irrigation system according to any preceding claim, wherein the planting area comprises a first layer, comprising soil or planting medium into which plants are planted.
21. A rainwater irrigation system according to any preceding claim, wherein a rainwater storage volume is also provided adjacent to or below the planting area.
22. A rainwater irrigation system according to claim 21, wherein the rainwater storage volume comprises a packing material.
23. A rainwater irrigation system according to claim 22, wherein the packing material comprises at least one of gravel and comminuted material, such a ground tyres.
24. A rainwater irrigation system according to claim 21 or 22, wherein an impermeable barrier is provided between a building wall and the planting layer and/or between the building wall and the rainwater storage.
25. A method of rainwater irrigation, comprising using the rainwater irrigation system of any preceding claim.
26. A rainwater irrigation system, substantially as herein described with reference to the accompanying drawings.
27. A method of rainwater irrigation, substantially as herein described with reference to the accompanying drawings. £Amendments to the claims have been filed as follows: 1. A rainwater irrigation system, comprising means for receiving rainwater from a roof surface, a substantially horizontal rainwater distribution pipe, having at least one rainwater distribution part, means being provided for feeding rainwater from the means for receiving rainwater to the rainwater distribution pipe, at least one overflow hole in the rainwater distribution pipe being provided, a second overflow being provided in the means for receiving rainwater, wherein the second overflow is configured to allow rainwater to flow out of the means for receiving rainwater when the level of rainwater in the means for receiving rainwater is at a predetermined height, the predetermined height being in the range up to 10mm above the maximum height of the rainwater distribution pipe.2. A rainwater irrigation system, comprising means for receiving rainwater from a roof surface, a substantially horizontal rainwater distribution pipe, having at least one rainwater distribution part, means being provided for feeding rainwater from the means for receiving rainwater to the rainwater distribution pipe, at least one overflow hole in the rainwater distribution pipe being provided for allowing rainwater to flow out of the overflow hole in the rainwater distribution pipe. 0** : 20 3. A rainwater irrigation system according to claim 2, wherein there is a plurality of S.....* * overflow holes **.* * * I 4. A rainwater irrigation system according to claim 1, wherein the second overflow comprises at least one overflow hole. 0I * * I I * SI5. A rainwater irrigation system according to claim 4, wherein the second overflow comprises at least one weir in the rainwater receiving means.6. A rainwater irrigation system according to claim 1, 4 or 5, wherein the means for feeding rainwater from the means for receiving rainwater to the rainwater distribution pipe comprises a diverter, the diverter including the second overflow.A p7. A rainwater irrigation system according to any of claims 1 or 4 to 6, wherein the second overflow comprises a valve which is configured to open when the height of water exceeds 10mm above the maximum height of the rainwater distribution pipe.B. A rainwater irrigation system according to any preceding claim, wherein the means for receiving rainwater has a maximum outer dimension of at least 75mm, preferably at least 100mm.9. A rainwater irrigation system according to any preceding claim, wherein the outer dimension of the means for receiving rainwater is no more than 200mm, preferably no more than 150mm.10. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution pipe has an outer dimension of at least 75mm, preferably at least 100mm and more preferably at least 125mm.11. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution pipe has a maximum outer dimension which does not * . 20 exceed 300mm, being preferably not greater than 250mm. p* .fl*. * *12. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution pipe has an outer dimension in the range 100mm to 250mm. *. ** p S ** * 13. A rainwater irrigation system according to any preceding claim, wherein the means for receiving rainwater and the rainwater distribution pipe are connected by at least one of an elbow junction or a T-junction.14. A rainwater irrigation system according to any preceding claim, wherein the means for receiving rainwater and the rainwater distribution pipe are connected by a connection in which there is substantially no narrowing.AS15. A rainwater irrigation system according to any preceding claim, wherein the sectional area of the rainwater distribution pipe is greater than that of the rainwater receiving means.16. A rainwater irrigation system according to any preceding claim, wherein the sectional area of the rainwater distribution pipe is at least 1.25 times the cross sectional area, more preferably at least 1.5 times the cross sectional area of the rainwater receiving means.17. A rainwater irrigation system accorthng to any preceding claim, wherein the rainwater distribution device comprises at least one rainwater distribution hole formed in the rainwater distribution pipe.18. A rainwater irrigation system according to any preceding claim, wherein the rainwater distribution device comprises at least one tap.19. A rainwater irrigation system according to any preceding claim, further comprising at least one planting area for receiving rainwater from the rainwater distribution pipe.S* * 20 d St 20. A rainwater irrigation system according to claim 19, wherein the planting area comprises a first layer, comprising soil or planting medium into which plants are planted.21. A rainwater irrigation system according to claim 19, wherein a rainwater storage volume is also provided adjacent to or below the planting area.22. A rainwater irrigation system according to claim 21, wherein the rainwater storage volume comprises a packing material.23. A rainwater irrigation system according to claim 22, wherein the packing material comprises at least one of gravel and comminuted material, such as ground tyres. a24. A rainwater irrigation system according to claim 21 or 22, wherein an impermeable barrier is provided between a building wall and the planting layer and/or between the building wall and the rainwater storage volume.25. A method of rainwater irrigation, comprising using the rainwater irrigation system of any preceding claim.26. A rainwater irrigation system, substantially as herein described with reference to the accompanying drawings. p. * * 0 * 0.I* I0*0 * *S Ip * 0 5-*5 *5 * * a Se * * a. * 5