GB2437527A

GB2437527A - Rainwater augmented domestic low-pressure water supply

Info

Publication number: GB2437527A
Application number: GB0607960A
Authority: GB
Inventors: Ian Shephard
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-04-24
Filing date: 2006-04-24
Publication date: 2007-10-31
Also published as: GB0707710D0; GB0607960D0; GB2437625A; GB2437625B

Abstract

A water supply system for a building having rainwater guttering comprises a receiver (21) mountable in or on the building beneath the rainwater guttering and means (20) for directing rainwater from the guttering into the receiver. A first water level detector (10) is associated with the receiver for detecting a predetermined minimum water level in the receiver. A water storage tank (13) in the building is connected to at least one water outlet in the building and is sufficiently elevated above the or each outlet to provide a flow of water from the outlet. The mains water supply to the storage tank is controlled in conventional manner by a float valve (18) which closes at a first level in the tank. A second water level detector (12) is associated with the storage tank for detecting a predetermined maximum water level in said tank above said first level. A pump (9) is provided for pumping water from the receiver (21) to the storage tank (13) through filters (15, 16) and a sterilizer (17) when the first water level detector indicates a level above the predetermined minimum and the second water level detector indicates a level below the predetermined maximum.

Description

RAINWATER AUGMENTED DOMESTIC LOW-PRESSURE WATER SUPPLY

Field of the Invention

This invention relates to a water supply system, for example for domestic use.

Background to the Invention

Increases in population, and climate changes causing periods of drought, have led to unsustainable demands being placed on potable water supplies. In a typical domestic dwelling, only a proportion of the supplied water is used for human consumption, the rest being used for washing, bathing and flushing toi-lets, for which purposes lower water purity standards are acceptable. At the same time, rainwater drainage from urban areas is creating a serious problem of increased flood risk. There is an urgent requirement to find a cheap, easily installed, and safe means of collecting additional water for domestic use while at the same time reducing rainwater run-off.

The typical domestic dwelling is provided with a high-pressure mains supply that generally feeds the cold-water circuit, and a storage tank located at a high level in the building, usually in the roof space. The storage tank provides a low-pressure supply to the hot water circuit and a cold water supply to appli-ances requiring both hot and cold feed at the same pressure, such as showers and baths. WCs may be fed from either the high-pressure or low-pressure cir-cuit and are generally fitted with pressure restrictors at their inlet valves when connected to the high-pressure circuit.

The water stored in the storage tank in the roof space is vulnerable to contamination by airborne micro-organisms, dust, smoke, insects, vermin, bats and birds, unless properly protected. Statutory Instrument 1999 No 1148 -The Water Supply (Water Fittings) Regulations 1999 -specifies requirements to protect such storage tanks from contamination by providing an overtlow pipe which excludes insects, and a cover to exclude light and insects. However, this cannot guarantee 100% protection from all possible contamination, particularly airborne micro-organisms, and for this reason water in a hot water distribution system is categorised in the Regulation as Fluid Category 2, and the incoming supply of mains water has to be protected from back siphoning by an air gap, usually via a standard ball valve. It should be noted that these regulations are not retrospective -storage tanks in properties constructed before 1999 may have little or no protection from contamination.

There have been various proposals for the collection and utilisation of rainwater. For example, GB2228521 describes a roof tile collector that feeds rainwater directly into the storage tank via the tank's overflow pipe. This re- quires the correct positioning of the tank inside the building relative to the gut-tering; in many buildings the required relationship between the two could not be achieved.

AU2003268574 is an example of a document which describes a device for intercepting rainwater from a down pipe with output via a tap. GB2231 907 describes a low-level storage tank for rainwater intercepted from a down pipe, again with output via taps. US2004108266 describes a tank-cleaning device suitable for large rainwater storage tanks.

Summary of the Invention

According to the invention, a water supply system for a building having rainwater guttering comprises a receiver mountable in or on the building be-neath the rainwater guttering, means for directing rainwater from the guttering into the receiver, a first water level detector associated with the receiver for de-tecting a predetermined minimum water level in the receiver, a water storage tank at a location in the building connected to at least one water outlet in the building and sufficiently elevated above the or each outlet to provide a flow of water from the outlet, a mains water supply to the storage tank controlled by a float valve which closes at a first level in the tank, a second water level detector associated with the storage tank for detecting a predetermined maximum water level in said tank above said first level, and a pump for pumping water from the receiver to the storage tank when the first water level detector indicates a level above the predetermined minimum and the second water level detector indi-cates a level below the predetermined maximum.

Preferably, a third water level detector is provided in association with the receiver to detect when the water level in the receiver reaches a maximum and to initiate operation of the pump if the second water level detector indicates a level below the predetermined maximum.

Preferably, the water from the receiver is pumped through water cleaning means before entering the storage tank. The water cleaning means may com-prise a filter, for example a replaceable cartridge filter, and preferably comprises two filters with successively finer filtration, for example a 5 micron filter followed by a 1 micron filter. More preferably, the water cleaning means includes a steri-lizer to destroy bacteria in the water. The sterilizer suitably includes an ultra violet lamp. The sterilizer preferably contains an alarm, which operates to pro-vide an alarm signal when the light intensity has deteriorated with age to the point that it is no longer effective and the lamp needs to be replaced. This alarm signal may be used to provide an additional control of the power supply to the pump so that the pump will not operate when the light is inadequate. The sys-tem is therefore fail-safe. At the same time as changing the UV lamp the filters would also be changed. The replacement of these items is the only essential maintenance activity required although a periodic inspection of the gutters, col-lection device and down pipes is advisable to ensure they are free of debris.

Filtration and sterilization of the water pumped from the receiver will en-sure that it is of a standard at least as high as the water already stored in the storage tank. On the other hand, if a separate storage tank and pipework are used exclusively to supply non-potable water, for example for WC flushing, the cleaning means could be dispensed with.

The water cleaning means may be incorporated into a single enclosure with the receiver, so that the receiver, water cleaning means and pump can be fitted as a single unit to which only the necessary water connections need to be made. The electricity supply for the pump, controls and sterilizer may be from the building's mains supply, but it might also be possible to incorporate into the unit enclosure a battery supplied by renewable energy, for example from a photovoltaic panel or a wind generator, thereby making the device self-contained.

Alternatively, at least some of the components, for example the water cleaning means, may be located remotely from the receiver, for example in the roof space of the building adjacent to the storage tank.

The receiver preferably includes means for separating larger solids from the water stored therein. These may include a primary filter and/or an adapta-tion to the inlet to the receiver to divert larger particles and debris into the drain.

Preferably, the adaptation includes a guide surface for incoming water which employs the Coanda effect to divert water into the receiver while allowing solids to drop into the drain.

The invention provides a basic system which supplies rainwater to aug-ment the existing low-pressure water circuit and, apart from the adjustment of the ball valve, requires no modification to the existing plumbing. As a minimum, the supplied rainwater will augment the feed to the hot water system. Potentially the storage tank could also supply the cold feed to baths, showers, washing machines and WC's if it does not already do so. The extent of plumbing modifi- cations required would vary enormously from property to property and the ex-tent of the work would be at the discretion of the property owner. If all or most of such appliances are to be supplied then the storage capacity should be in-creased by installing a larger storage tank, or a second storage tank alongside and interconnected to the existing tank. All these considerations can be readily accommodated in the design of new properties.

In hard water areas there is an additional advantage. Rainwater is soft water and its use in the way described will help reduce the amount of soap and detergent required for washing. In properties already fitted with water softeners the volume of water drawn by the system from the softener will be reduced by the use of rainwater thus enabling regeneration cycles to be lengthened and salt consumption to be reduced

Brief Description of the Drawings

In the drawings, which illustrate an exemplary embodiment of the inven-tion: Figure 1 is a part-sectioned diagrammatic representation of the system of the invention; and Figure 2 is a diagram of the pump operating relay circuit of the system of Figure 1.

Detailed Description of the Illustrated Embodiments Referring to Figure 1, rainwater from the roof is fed via gutters and down-pipe 20 to a receiver unit 21 mounted on the exterior wall of the building as close as possible to the gutter/down-pipe connector. Incoming water, which may be contaminated with floating debris such as leaves and solid debris such as grit, is fed down an input chute 1 inclined at an angle slightly below the horizon-tal. This chute terminates in a downward curved surface 2, which curves under the chute 1. The water clings to the curved surface and is carried backwards through a comb 3 and over a divider 4 to fall into a collection chamber 5. All but very small solid contaminants are collected by comb 3 and drop into the dis-charge chamber 6, to be discharged into the drain in the usual manner.

As the water level rises in the collection chamber 5 it flows through a primary filter 7 into a delivery chamber 8 containing a submerged electric pump 9, a low-level float switch 10 and a high-level float switch 11. The water level rising in the delivery chamber 8 closes the low-level float switch 10 followed by closing of the high-level float switch 11. The output from the pump 9 is directed through successive filters 15 and 16, and a sterilizer unit 17, which incorporates a UV lamp, to discharge into the standard storage tank 13 in the building, which is adapted by the provision of a high level float switch 12 and by adjusting the mains water-controlling float valve 18 so that the valve shuts off at a level below the level detected by the float switch 12, for example with the tank half full.

Provided the high level float switch 12 fitted to the storage tank 13 is closed and the lamp in the UV sterilizer 17 is serviceable, the initial closure of high-level float switch 11 causes a relay 14 (see Figure 2) to close. This relay completes two circuits -a hold on' circuit via the low-level float switch 10 to maintain the relay in the closed position, and the supply circuit to the pump. The pump 9 starts to run to empty the delivery chamber 8 via the filters 15 and 16 and the UV sterilizer 17 into the storage tank 13.

Adjustment of the float valve 18 so that it closes once the tank is half full leaves the remaining capacity of the tank available for the incoming processed rainwater while ensuring that an adequate supply is always available for use even in periods of drought. As the water level in the delivery chamber 8 starts to fall, the high-level float switch 11 opens again but the hold on' circuit maintains the power supply to the pump 9 and the water level continues to fall until the low-level float switch 10 opens. This breaks the hold on' circuit, tripping the re-lay and disconnecting the power supply to the pump. The cycle repeats as more rainwater feeds through to again raise the level in the delivery chamber 8.

In intense rainfall, the rate of input of rainwater may exceed the capacity of the pump and the water level in both the collection chamber 5 and the deliv-ery chamber 8 will continue to rise above the level defined by the high-level float switch 11. Also, if the storage tank is full or if the UV light is not working then the pump will not run and incoming rainwater will similarly raise these levels beyond the setting of the high-level float switch 11. In these circumstances, as the water level reaches the level of the output of overflow pipe 22, water will start to flow through the overflow pipe and discharge into the discharge chamber 6. In this process suction is created at the bottom end of overflow pipe 12 which will draw any sediment from the bottom of collection chamber 5 and discharge it into dis-charge chamber 6, thus self-cleaning the collection chamber 5. The overflow pipe will slow the rate at which the water level will rise, but eventually the water level may reach the top of divider 4 and overflow into the discharge chamber 6, taking with it any floating debris and thus completing the self-cleaning process.

Claims

CLAIMS

1. A water supply system for a building having rainwater guttering comprises a receiver mountable in or on the building beneath the rainwater gut-tering, means for directing rainwater from the guttering into the receiver, a first water level detector associated with the receiver for detecting a predetermined minimum water level in the receiver, a water storage tank at a location in the building connected to at least one water outlet in the building and sufficiently elevated above the or each outlet to provide a flow of water from the outlet, a mains water supply to the storage tank controlled by a float valve which closes at a first level in the tank, a second water level detector associated with the storage tank for detecting a predetermined maximum water level in said tank above said first level, and a pump for pumping water from the receiver to the storage tank when the first water level detector indicates a level above the pre-determined minimum and the second water level detector indicates a level be-low the predetermined maximum.

2. A water supply system according to Claim 1, wherein a third water level detector is provided in association with the receiver to detect when the wa-ter level in the receiver reaches a maximum and to initiate operation of the pump if the second water level detector indicates a level below the predeter-mined maximum.

3. A water supply system according to Claim 1 or 2, comprising wa-ter cleaning means between the pump and the storage tank.

4. A water supply system according to Claim 3, wherein the water cleaning means comprise a filter.

5. A water supply system according to Claim 4, wherein the water cleaning means comprise at least two filters with successively finer filtration.

6. A water supply system according to any preceding claim, wherein the water cleaning means comprise a sterilizer.

7. A water supply system according to Claim 6, wherein the sterilizer includes an ultra violet lamp.

8. A water supply system according to Claim 7, wherein the sterilizer contains an alarm, which operates to provide an alarm signal when the light in-tensity of the UV lamp has deteriorated with age to the point that it is no longer effective and the lamp needs to be replaced.

9. A water supply system according to Claim 8, wherein the alarm signal is used to provide an additional control of the power supply to the pump so that the pump will not operate when the light is inadequate.

10. A water supply system according to any preceding claim, wherein the water cleaning means is incorporated into a single enclosure with the re-ceiver.

11. A water supply system according to any preceding claim, wherein the receiver includes means for separating larger solids from the water stored therein.

12. A water supply system according to Claim 11, wherein the sepa-rating means comprise a primary filter.

13. A water supply system according to Claim 11 or 12, wherein the separating means comprise a guide surface employing the Coanda effect to di-veil water into the receiver while allowing solids to drop into a drain.

14. A water supply system according to any preceding claim, compris-ing a battery to provide electrical power for the pump and, if required, for the water cleaning means, and electricity generating means to recharge the battery.

15. A water supply system according to Claim 14, wherein the elec-tricity generating means comprise a photovoltaic panel or wind generator.

16. A water supply system for a building, substantially as described with reference to, or as shown in, the drawings.