GB2331323A

GB2331323A - Domestic water supply system

Info

Publication number: GB2331323A
Application number: GB9723921A
Authority: GB
Inventors: John Frederick Lawrence
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-11-12
Filing date: 1997-11-12
Publication date: 1999-05-19
Anticipated expiration: 2017-11-12
Also published as: GB2331323A9; GB9723921D0; GB2331323B

Abstract

In order to collect and make available grey water and rain water so that they can be used for example in irrigation and toilet flushing, grey water is collected from domestic washing facilities and stored in a grey water tank (14), rain water is collected and stored in a rain water tank (not shown), flow of water between the grey water tank and rain water tank being substantially impeded, grey water and rain water being pumped from the grey water tank and rain water tank to a point at which grey water and rain water are put to use using a pump means which is for pumping water both from the grey water tank and the rain water tank.

Description

2331323 System for Collecting and Making Available Grey Water and Rain

Water.

The present invention relates to improvements in and relating to systems for collecting and making available various forms of waste water, which can be used in various applications to supplement the normal mains water supply.

Over the past few years, attention has been focused on reducing the use of treated water, in particular in response to climate changes in the United Kingdom and elsewhere, increasing consumer demand and also in response to a general desire to conserve resources. Accordingly, systems have been proposed for collecting, storing and delivering water such as rain water or so-called "grey water". The term "grey water" denotes lightly soiled water from domestic washing facilities such as hand wash basins, sinks, baths, showers etc. The collected water can be used typically for irrigation of the garden (particularly in the summer months) or as toilet flushing water.

Heavily soiled water such as water from toilets or from kitchen waste disposal units is commonly termed 'Mack water". It is normally unsuitable for reuse in the domestic context as it requires considerable amount of treatment before it can be reused.

Such systems for using grey water and/or rain water may also include features such as overflow from storage tanks to the main drainage system and auxiliary feed of mains water to the system in case the supply of rain water/grey water falls below a certain level.

Systems for the use of grey water in toilet flushing and/or irrigation are described in GB 2253235,GB227372andWO94/10892. Systems for the use of grey water supplemented with rain water in flushing toilets are described in WO 94/10892, GB 2302904 and GB 2249121. Systems for the use of grey water supplemented with rain water for both toilet flushing and irrigation are described in GB 2236138 and WO 97/33676.

Although grey water is lightly soiled, it may contain small levels of bacterial material. It is desired to destroy this bacteria as much as possible before using it in irrigation. Slowly dissolving tablets which yield chlorine on solution have been proposed in relation to the use of grey water in toilet flushing and in irrigation have been proposed. However, there is a problem that chlorine can be toxic to plants and soil life, which can make it unsuitable for use in irrigation systems.

Problems have been encountered in selecting the size of the tank for storing water for reuse. If the tank is too large, the rate of changeover of water contained in the tank may be very low, leading to stagnation and fouling of the water. If the tank is too small, it may not be able store a useful quality of water.

The present inventor has now realised that, where a system makes use of both rain water and grey water, separate storage means can be provided for the rain water and grey water, allowing the respective tanks to be optimised to the particular rate of supply of rain or grey water. Further, a single pump can be provided to deliver water from both of the rain water and grey water tanks to the point of use without any problems of cross infection.

Accordingly, the present invention provides a system for collecting and making available grey water and rain water from domestic sources, comprising:

means for collecting grey water from domestic washing facilities, a grey water tank for storing collected grey water, means for collecting rain water, a rain water tank for storing collected rain water, at least one pump means for pumping grey water and rain water from the grey water tank and the rain water tank respectively, to a point at which grey water and rain water are to be put to use, wherein flow of water between the grey water tank and the rain water tank is substantially impeded and wherein the or each pump means is for pumping water from both the grey water tank and the rain water tank.

In a second aspect, the present invention provides a method of collecting and making available grey water and rain water from domestic sources, comprising collecting grey water from domestic washing facilities, storing the grey water in a grey water tank, collecting rain water, storing collected rain water in a rain water tank, wherein flow of water between the grey water tank and the rain water tank is substantially impeded, and pumping grey water and rain water from the grey water tank and rain water tank to a point at which grey water and rain water are to be put to use, wherein grey water and rain water are pumped by the same pump.

The present invention also extends to a kit of parts for installing a system according to the present invention, the kit comprising pipe means for collecting grey water and rain water, grey water tank and rain water tanks and pump means, the pump means being arranged for pumping water from both the grey water tank and rain water tank when installed.

With the system of the invention, the size of the grey water and rain water tanks may each be separately set so that, taking into account the expected rate of supply of rain water or grey water, the residence time of water in that tank is kept relatively low, so that it does not become anaerobic and foul, whilst still storing a useful volume of water.

Preferably, the grey water tank and rain water tank are located near to one another, so that the distance from the tanks to the pump may be made substantially the same and as small as possible. For example, the tanks may comprise separate containers located near one another or they may comprise separate compartments of a single container.

Flow of water between the grey water and rain water tanks is substantially impeded. This means that, as far as possible, there will be no flow one way or the other between the tanks. There is a possibility that there could be flow from one tank to the other via the pump. To prevent or reduce this, the pump means may be suitably designed so that there is substantially no communication between the tanks. Non-return valves may be provided between the tanks and the pump so that water drawn into the pump will not go back into either tank.

In this way, the invention provides a simple, inexpensive and flexible system for maximising use of waste water. Preferred features of the invention are as follows.

The grey water and/or rain water collected can be made available for use as flushing water for toilets, in garden irrigation or in general exterior use, e.g. for washing vehicles.

In order to allow grey and/or rain water (hereinafter "collected water") to be used in toilets, the pump preferably pumps the collected water along a pipe to a holding tank such as a break tank at high level. For example, the break tank may be in the loft space. The holding tank should be placed at a height which allows water to be fed under - 5 gravity to toilets. When full, a valve such as a ball-valve in the holding tank may closeoff the supply of water from the pump. The resulting increase in pressure in the pipe from the pump preferably operates pressure sensitive means such as a pressure switch to switch off the pump. The holding tank preferably includes an auxiliary mains water supply. The auxiliary mains water supply may be operated by a ball-valve and fed through a non-return valve. The auxiliary mains supply preferably introduces mains water if the level of water in the holding tank drops below a certain level. Preferably, there is also an overflow in the holding tank whereby excess water may be drained away, for example back to the grey water storage tank or out through an overflow or to discharge externally. Preferably, the level of the overflow is below the input level of the auxiliary mains supply.

The holding tank may be insulated to prevent freezing in winter.

In irrigation, the system may be used to service specialist automatic underground irrigation systems including pop-up sprinklers and porous trickle feed pipes. Control means may be provided as discussed below. Fertiliser/weed killer dispensers may be provided in the irrigation system.

Grey water is collected for example from baths, showers, basins and sinks and similar washing facilities. Preferably, water will not be taken from dishwashers or clothes washing machines, because such water may contain components such as borates which are toxic to plants. Further, water from kitchen sinks and waste disposal units will not normally be used, as they can contain a very high level of solids which can give problems due to fouling of filters and rapid stagnation of the water or bacterial buildupHowever, water treatment means such as settling tanks, sand filters, aerobic treatment tanks, or septic tanks may be used to provide treated black water. Infra-red or other supplementary treatment could be used to purify discharge from a septic tank or the like to a suitable standard. Rain water can be collected from the guttering system of the building. Grey water can be collected by a separately installed system of pipes, or by interceptors placed in existing piping systems for delivering the grey water to the drainage system. It is important that grey water collected for the use according to the present invention is not in contact in any way with foul water from the toilets etc.

Collected water preferably passes down replacement or existing drainage pipes to back inlet gullies, for example, to provide an odour trap and access f ilters.

for cleaning and access to The present invention is suitable for domestic and some commercial use. This includes houses, bungalows, flats, commercial sites, camping sites etc. or any similar installation which has similar patterns of grey water generation, water external use (for example for irrigation) and similar demands for toilet flushing.

The means for collecting water and/or the means for storing collected water preferably comprises filter means for removing solids from the collected water. Thefiltersmaybe for collecting granular materials such as grit, soap remains, scum, hair etc. There may be a single filter. However, preferably there are a plurality of filters arranged in sequence, with the coarsest filter first. Preferably, the filters are arranged in gullies or with man-holes so that they can be readily accessed for cleaning andlor replacement. For example, filters may be provided respectively in the gully, in the tank and in the line connecting the tank and the pump. The filters may comprise barrier filters, for example made in synthetic materials, cyclone filters for centrifuging out heavier than water solids, packed bed filters such as sand filters etc.

The means for storing collected water typically comprise metal (e.g. steel), glass reinforced plastic, or reinforced plastic tanks (e.g. polyethylene). Typically, they are placed below ground level. This has advantages of easy support of the containers, ready flow under gravity to the tanks, easy flow from the tanks to overflows, easy access via normal gullies/man-holes for servicing and protection from light frost.

Means for disinfecting collected water may be provided, for example in the means for storing collected water. For example, anti-bactenial chemicals could be introduced into the water in the storage means. Preferably, the anti-bacterial agent comprises chlorine. This chlorine may be provided by an automatic dosing system as in public swimming baths or, more simply, by slow dissolving tablets. Such slow dissolving tablets may be contained in a cage or trap suspended at low level in the containers for collected water. Preferably, means are provided to allow access to the tank to replace or restore the source of disinfectant chemical. Access to test water for purity is preferably through the grey/rain water inlet.

It will be a simple matter for a person skilled in the art to select an appropriate rate of feed of disinfectant chemical so that, given the normal rate of through flow of collected water, the build-up of disinfectant chemical in the collected water is maintained at a low level whereby toxic levels of disinfectant are not fed to plants. For example, the number of tablets required to be placed in the tank at any one time can be altered according to the rate of flow of collected water through the tank.

The tanks are preferably of size in the region 1,000-10,000 litres, for example 1,4009,000 litres. The tanks can comprise vessels of any suitable shape. For example, they may comprise spheroidal or cylindrical vessels, preferably having at least one extension volume or 'turret' for housing for example the pump or inlet means.

Overflow means may be provided in both tanks. The tank for collected grey water should overflow into the foul water drainage system, preferably through a trap such as a S-bend. The tank for collected rain water should overflow into a normal rain water storm drain or soak-away system (e.g. a perforated pipe in a trough in the ground lined with sand or gravel).

The skilled person will be able to select the power of the pump required in dependence upon height to which the water should be pumped, the pressure required and the rate of flow of water required. For example, the pump may be in the range 300 to 5,000 watts more preferably 500-3,000 watts.

A control system may be provided to allow substantially automatic operation of the system. In a first aspect, the control system will comprise means for controlling the rate of supply of irrigation water and timing. For example, such control means may comprise sensors for determining rain fall, moisture level etc. in the soil. Further, a timer may be incorporated whereby a given quantity of water may be delivered at a given time each day. In a second aspect, the control system may monitor the water level in the break tank for toilet flushing water. Once the water level falls below a certain level, preferably a level above that which auxiliary mains water is supplied, a signal is given to the pump whereby a given volume of water is delivered to the break tank. Alternatively, the pump may be allowed to operate until the level of water in the break tank exceeds a certain level which is below the overflow level. A sensor, such as a float switch or a float operated valve may be provided in each of the tanks for collected water whereby operation of the pump may be disabled if the water level in the tanks is too low. Signal giving means may be provided on an outside tap, delivery point or the like, to operate the pump when water is required at the tap or delivery point.

The pump itself is Preferably provided at a level in the collected water tanks above the overflow water level. This will allow the pump to be protected from inundation with water which could damage the pump. Small holes (weep holes) may be provided in the top of the tank below pump level to allow any seepage from the pump to drain away back into the tank.

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

Figure 1 is a schematic plan view of a house having a system according to the present invention.

Figure 2 is a schematic vertical section of a house having a system according to the present invention.

Figures 3 and 4 show end and side views respectively of the containers for collected grey water and rain water.

In Figure 1, a system according to the invention is shown installed in a house. Grey water is collected by pipes (10) from facilities such as the bath (11) and hand wash basin (12). Collected grey water flows via a back inlet gully (13) to a grey water storage tank (14) located below ground level outside the house.

Rain water is collected by pipes (20) from gutter down pipes (21) [not all are shown for clarity]. The collected rain water is fed to rain water storage tank (22).

The grey water storage tank comprises an overflow (15) which feeds into the main foul drain (16) along with black water collected from the kitchen sink (17) and toilet (18), The rain water storage tank (22) has an overflow comprising a soak-away in the form of a perforated polythene pipe located in a gully in the earth packed with gravel. The grey water storage tank and rain water storage tank have turrets (19) and (24) respectively for access for example for cleaning.

In the grey water storage tank (14) there is a pump (3 0) which draws water both from the grey water storage tank via a suction line (3 1) and from the rain water storage tank via a suction line (32). The collected rain water and collected grey water are delivered mixed from the pump (30). The pumped water may be delivered to irrigation means, for example a tap (33). Preferably, the tap comprises a switch for giving electrical signals to operate the pump (30). Alternatively, pumped water may be delivered via a pressure line (34) to a loft tank (40) for supplying flush water for toilets. Loft tank (40) may have a mains auxiliary water supply, as described in relation to Figure 2 below.

Figure 2 is a schematic elevation of the system of Figure 1. Only the grey water storage tank (14) is visible, showing the positions of the manholes (19), the pump (30), pressure line (34), toilet (18), loft tank (40).

The auxiliary mains water supply (41) is for supplying water to the loft tank (40) when the level of water therein is too low. A ball-valve (42) is provided for operating the auxiliary mains supply. The auxiliary mains (41) contains a non-return valve (not shown). Further, an overflow from the loft tank (43) is provided below the level of the input from the mains auxiliary supply (41). Water is supplied by a line (44) to the toilet (18) in the normal fashion. The pressure line (34) is provided in the loft with a ballvalve (45) which is intended to shut-off the supply of pressure from the line (34) to the tank (40) when the water level reaches a given height. A pressure sensor (54) is provided in the pressure line (34) for determining when the pressure increases due to the ball-valve (45) shutting-off. This pressure sensor gives a signal to switch off the pump (30). When the level in the water tank (45) has dropped below a given level, the ball-valve (45) automatically gives a signal to the pump (30) whereby water is pumped from the tanks (14) and (22).

Figure 3 shows the detail of the grey water and rain water storage tanks.

Filters (50) and (5 1) respectively are provided in the rain water tank (22) and grey water tank (14). Preferably, they comprise synthetic barrier filters or packed bed filters such as sand filters. They are placed in the inlets where they are accessible for cleaning via turrets (19). Further, suspended from the turrets (19) there are chemical treatment means (52) and (53) respectively. These comprise containers, for example perforated baskets, for slow dissolving tablets which release chlorine on solution. They are placed for ready access via turrets (19) for replacement and cleaning. A pressure sensor (54) is provided in the pressure lines (34) for determining when the loft ball-valve (45) shutsoff the supply of water from pump (32) to the loft tank (40).

The present invention has been described above by way of example only and modifications can be made within the invention. The invention also consists in any individual features described or implicit herein or shown or implicit in the drawings or any combination of such features or any generalisation of any such features or combinations.

Claims

CLAIMS:

1. A system for collecting and making available grey water and rain water from domestic sources, comprising:

means for collecting grey water from domestic washing facilities, a grey water tank for storing collected grey water, means for collecting rain water, a rain water tank for storing collected rain water, at least one pump means for pumping grey water and rain water from the grey water tank and rain water tanks respectively, to a point at which grey water and rain water are to be put to use, wherein flow of water between the grey water tank and rain water tanks is substantially impeded, and wherein the pump means is for pumping the water from both the grey water tank and the rain water tank.

2.

A method of collecting and making available grey water and rain water from domestic sources, comprising:

collecting grey water from domestic washing facilities, storing collected grey water in a grey water tank collecting rain water, I- - 13storing collected rain water in a rain water tank, wherein flow of water between the grey water tank and the rain water tank is substantially impeded, and pumping the grey water and rain water from the grey water tank and rain water tank to a point at which grey water and rain water are to be put to use, wherein grey water and rain water are both pumped by the same pump means.