GB2383373A

GB2383373A - System for reusing grey water

Info

Publication number: GB2383373A
Application number: GB0130275A
Authority: GB
Inventors: John Gowan Lomas
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-12-19
Filing date: 2001-12-19
Publication date: 2003-06-25
Anticipated expiration: 2021-12-19
Also published as: GB2383373B; GB0130275D0

Abstract

The system for reusing grey water, which is particularly for use in a domestic environment, comprises a receiver for receiving waste water from a source plumbing installation, a storage tank 12, a transfer unit 10 for transferring water from the receiver to the storage tank and a feed system for transferring water from the storage tank to a target plumbing installation 70, wherein the storage tank is at a height greater than that of the target plumbing installation so that water can be transferred from the tank to the target plumbing installation under the action of gravity. The source plumbing installation is may include one or more of a bath, a wash-hand basin or a shower, while the target plumbing installation may include one or more of a toilet cistern, a horticultural irrigation system or a shower. The transfer unit may be a pump 14 which operates only when required and the unit may also include a detection means such as a pressure switch which operates the pump on detection of water. The receiver may include a reservoir 24 for receiving water from the source installation which is smaller than the storage tank and in which the pump may be submerged. The reservoir may contain less water than is normally released from the source plumbing installation and water not transferred to the storage tank may be transferred to a waste water disposal outlet 44. The storage tank may include a limit valve that limits that amount of water that can enter the tank and a second valve 64 which operates to introduce mains water if the level of water in the tank falls below a minimum level. A dosing unit 16 may operate to add a quantity of conditioning chemical to the water and the unit may introduce the chemical as the water leaves the transfer unit or into the water in the storage tank, with the dosing unit and transfer unit sharing a common housing in the former case. A drainage system may prevent water from remaining in the storage tank for an excessive period of time that includes a valve 78 that periodically opens to drain the tank.

Description

Waste water processing system This invention relates to a waste water processing system. In particular, it relates to a system for processing grey water in a domestic environment.

At present, most domestic premises are provided with a single supply of water that has been processed to a standard that is high enough to enable the water to be fit for human consumption without any further processing. Since most premises have just one supply of water, much of this water is used for a various purposes that do not require water processed to such a high standard. Moreover, many premises have just one waste water removal system, water entering the system being processed to render harmless the worst contamination that might be contained in the water, yet much waste water is only lightly contaminated.

Since the treatment of both supply water and waste water has an environmental impact and a financial cost, the conventional systems for water supply, use and treatment are doubly wasteful. Water of unnecessarily high quality is used for many tasks in which the water is not required for human consumption, and lightlycontaminated waste water is removed and is subject to treatment that is beyond what is necessary.

It has been recognised that water that has been used, but which is not heavily contaminated, can be re-used in an application in which high purity is not essential.

This water is known as"grey water". An example of grey water is water drained from a bath or shower. An example use of grey water is in flushing a toilet.

Various schemes for re-cycling grey water have been proposed. The disclosures of DE-A-4001635 and DE-A-3932022 describe systems in which water is collected from baths, showers and so forth, drained into a tank, and subsequently pumped to a header tank for re-use. A disadvantage with such systems is the need to install a large collection tank, which is likely to be costly and inconvenient and may not be

possible in some cases. Moreover, the installations as a whole are complex. Other proposals for grey water recycling include the disclosure of US-A-have as an aim the processing of grey water to produce potable water. Such systems are economically viable only where the availability of potable water is restricted or is very costly; their use is not particularly appropriate for a small domestic installation in other circumstances.

An aim of this invention is to provide a system for grey water recycling that can be installed readily, to provide water at its output for use in conditions in which water of a potable standard of purity is not required.

Therefore, this invention provides a system for re-using grey water comprising a receiver for receiving waste water from a source plumbing installation; a storage tank; a transfer unit for transferring water from the receiver to the storage tank; and a feed system for transferring water from the storage tank to a target plumbing installation; in which: the storage tank is at a height greater than that of the target plumbing installation whereby water can be transferred from the tank to the target plumbing installation under the action of gravity.

Such a system can be installed using substantially fewer components and with substantially less complication than the systems known from previous publications.

In a typical installation, the source plumbing installation might include one or more of the following: a bath, a wash-hand basin or a shower. The target installation might include one or more of a toilet cistern, a horticultural irrigation system or an external water supply. (These lists should by no means be considered to be comprehensive; there are likely to be many other possible applications of the invention.)

The transfer unit may include a pump. Most advantageously, the transfer unit further includes detection means for detection of waste water from the source plumbing installation, the detection means being operative to cause the pump to operate upon detection of such water. In such embodiments, the pump operates only when required. For example, the pump may be an electric pump, and the detection means may include a pressure switch.

The receiver may include a reservoir for receiving water from the source plumbing installation. The reservoir can act as a source of water for the pump. In typical embodiments, the size of the reservoir is small; that is to say, it is substantially smaller than the storage tank. Moreover, the reservoir can most typically contain less water that is normally released from the source plumbing installation. For example, the reservoir may be dimensioned to contain no more than 5 litres of water. In embodiments according to this paragraph, the transfer unit may include a submersible pump.

Advantageously, water that enters the transfer unit which is not transferred to the storage tank is transferred to a waste water disposal outlet. This allows waste water to be processed if, for example, it arrives at a rate greater than the rate at which it can be processed by the transfer unit, and also ensures that spillage does not occur in the event of failure of the transfer unit.

The storage tank may include a level valve to limit the amount of water that can enter the storage tank. The storage tank may further include a second level valve that operates to introduce mains water into the storage tank in the event that the level of water in the tank falls below a threshold level.

A system embodying the invention most typically further comprises a dosing unit that operates to add a quantity of conditioning chemical to the water. The dosing unit may, for example, introduce the conditioning chemical into the water as it leaves the transfer unit. In such embodiments, the dosing unit and the transfer unit may be contained in a common housing. Alternatively, the dosing unit may introduce conditioning chemical into the storage tank. In such embodiments, the dosing unit and the transfer unit are typically remote from one another.

Embodiment of the invention may include a draining system that operates to ensure that water does not remain in the storage tank indefinitely. For example, the draining system may include a valve that is opened periodically to drain water from the storage tank.

Embodiments of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings, in which: Figure 1 is a block diagram of a first system embodying the invention; Figure 2 is a diagram of a transfer unit of the system of Figure 1; and Figure 3 is a logic diagram showing the sequence of operation of a system embodying the invention.

With reference first to Figure 1, a system embodying the invention is installed to receive waste water from a bath or a shower waste outlet and to provide that water to fill a toilet cistern.

The system of Figure 1 includes a transfer unit 10 and a storage tank 12. The transfer unit 10 incorporates a transfer pump module 14 and a dosing module 16 contained, for convenience of installation, within a common housing 18.

The transfer unit 10 has an input pipe 20 into which is fed waste water draining from the outlet of a bath and/or a shower. The input pipe 20 feeds water to an input port 22 a reservoir 24 within which the pump module is contained. The reservoir 24 serves as a waste water receiver, to supply water to an input port of the pump module 14. An electric submersible pump is disposed within the reservoir. The pump is controlled by a pressure switch that is located within the reservoir 24. The switch and pump and connected such that the pump can run only when water is present in the reservoir 24. The pump has an output port 26 that is connected to a non-return valve 28, which is, in turn, connected to an output pipe 30 of the transfer unit 10.

The dosing module 16 includes a reservoir 32 and a dosing pump 34 connected by a feed pipe 36. The pump, in this embodiment, is a peristaltic pump, this being

selected as being capable of dispensing a small and carefully measured quantity of liquid.

For use, the reservoir contains a concentrated bactericide. Conventional household bleach has been found to provide adequate bacteriological protection, and has advantages in that it is cheap and easy to obtain economically. During such time that the pump module 14 operates to pump waste water, the dosing pump 34 runs to pump the bactericide from the reservoir 32 into the outlet port 26 of the pump module 14. This ensures that the water exiting the pump module 14 is dosed with the concentrate at a substantially constant ratio. In order that the reservoir 32 can be refilled as required, it has a closure 38 that can be accessed through an upper panel of the transfer unit 10.

The reservoir 24 is provided with a second outlet 40 at a level above the inlet port 22. The second outlet 40 feeds waste water that exceeds a predetermined level to drain though a waste pipe 42 to waste at 44. This ensures that water which enters the transfer unit 10 and which is not removed by the pump is led away safely to waste.

Water that leaves the transfer unit 10 through the outlet pipe 30 is fed through a transfer pipe 50 to the storage tank 12, where it enters the tank through an upper

cover 52 through an inlet port 54. A flow detector 48 is located in the transfer pipe 50 to detect flow of water in the pipe 50. The flow detector 48 acts as a control for the dosing pump 48, energising the pump only when water is flowing in the outlet pipe 30.

The tank 12 has an outlet port 56 that extends through its sidewall close to the base of the tank. The outlet port 56 provides an outlet of the system from which water can be conveyed to water-consuming installations, in this case, a toilet cistern 70. A valve 58 is optionally provided in the outlet to enable water to be drawn off for testing.

Within the storage tank 12, devices are provided to control the level of water in the tank 12. First, a maximum level float switch 60 extends through a sidewall of the

tank 12. The float switch 60 has a pivoting arm 62, which can float upon water in the tank 12. When the water rises to raise the arm 62, the switch causes power to the pump 14 to be interrupted, thereby preventing further water being delivered to the tank 12. The tank also has a float-operated valve 64 that receives a feed of fresh mains water and controls its delivery into the tank 12. A float 66 carried on an arm 68 controls the float-operated valve 64. The float 66 and the arm 68 are configured such that the float-operated valve 64 opens only when a small amount of water remains in the tank 12 (say, enough to flush the toilet one or two times). This ensures that the tank 12 always contains enough water to meet a demand for water even when sufficient recycled waste water is not available. However, it ensures that fresh water is used only when its use is essential to meet such requirements.

It will be noticed from the drawing that the outlet from the float-operated valve 64 is separated vertically from the level of water in the tank. This is to comply with regulations in force in some jurisdictions that aim to ensure that grey water cannot contaminate the fresh water supply. In other regulatory environments, such a configuration may be unnecessary.

An optional feature of this embodiment ensures that water does not stay in the tank indefinitely. This can be undesirable under some environmental conditions (e. g. in warm countries) since it can give rise to a build-up of bacteria and other contamination in the event that the appliances fed by the system are unused for some time. This is implemented by provision of an outlet port 78 in the base of the tank connected to the drain 44 through a dump valve 80. The dump valve 80 is electrically controlled, whereby application of an electrical signal to the dump valve 80 causes water to drain from the tank 12 through the valve to the drain 44. To implement this feature, the dump valve may be actuated for a predetermined time once in a preset period (of, say, several days) to empty the tank completely.

Operation of the system is controlled by an electronic control unit that operates in accordance with the logic diagram shown in Figure 3. The control unit also operates three warning lights, one red, one amber and one green, to provide the user with a visual indication of the state of the system. Again, the sequence of operation of these lights is made clear in the logic diagram of Figure 3.

In the embodiment described above, the principal operational components of the system (the dosing unit and the transfer unit) are contained within the housing, which, in many cases, is advantageously compact and modular. However, in an alternative configuration, the dosing unit is positioned remote for the transfer unit, most typically close to the storage tank. This configuration can be advantageous for use where space available for the transfer unit is limited.

Claims

1. A system for re-using grey water comprising: a. a receiver for receiving waste water from a source plumbing installation; b. a storage tank; c. a transfer unit for transferring water from the receiver to the storage tank; and d. a feed system for transferring water from the storage tank to a target plumbing installation; in which: the storage tank is at a height greater than that of the target plumbing installation whereby water can be transferred from the tank to the target plumbing installation under the action of gravity.

2. A system according to claim 1 in which the source plumbing installation includes one or more of the following: a bath, a wash-hand basin or a shower.

3. A system according to claim 1 or claim 2 in which the target installation includes one or more of a toilet cistern, a horticultural irrigation system or an external water supply.

4. A system according to any preceding claim in which the transfer unit includes a pump.

5. A system according to claim 4 in which the pump operates only when required.

6. A system according to claim 5 in which the transfer unit further includes detection means for detection of waste water from the source plumbing installation, the detection means being operative to cause the pump to operate upon detection of such water.

7. A system according to claim 6 in which the pump is an electric pump, and the detection means may include a pressure switch.

8. A system according to any preceding claim in which the receiver includes a reservoir for receiving water from the source plumbing installation.

9. A system according to claim 8 in which a submersible pump is disposed within the reservoir.

10. A system according to claim 8 or claim 9 in which the size of the reservoir is substantially smaller than the storage tank.

11. A system according to claim 10 in which the reservoir can contain less water that is normally released from the source plumbing installation.

12. A system according to any preceding claim in which water that enters the transfer unit which is not transferred to the storage tank is transferred to a waste water disposal outlet.

13. A system according to any preceding claim in which the storage tank includes a level valve to limit the amount of water that can enter the storage tank.

14. A system according to any preceding claim in which the storage tank further includes a second level valve that operates to introduce mains water into the storage tank in the event that the level of water in the tank falls below a threshold level.

15. A system according to any preceding claim further comprising a dosing unit that operates to add a quantity of conditioning chemical to the water.

16. A system according to claim 15 in which the dosing unit introduces conditioning chemical into the water as it leaves the transfer unit.

17. A system according to claim 16 in which the dosing unit and the transfer unit are contained in a common housing.

18. A system according to claim 15 in which the dosing unit introduces conditioning chemical into the storage tank.

19. A system according to any preceding claim that includes a draining system that operates to ensure that water does not remain in the storage tank indefinitely.

20. A system according to claim 19 in which the draining system includes a valve that is opened periodically to drain water from the storage tank.

21. A system for re-using grey water substantially as herein described with reference to the accompanying drawings.