WO2013076229A1

WO2013076229A1 - System and method for distinguishing between grey water and black water

Info

Publication number: WO2013076229A1
Application number: PCT/EP2012/073430
Authority: WO
Inventors: Tatu Kemppainen
Original assignee: Tatu Kemppainen
Priority date: 2011-11-23
Filing date: 2012-11-23
Publication date: 2013-05-30
Also published as: FI20116164L

Abstract

The invention relates to a system and a method for handling waste water. The invention is especially applicable in detached houses and leisure homes such as summer cottages. It has been a problem to provide separate tubing for grey and black water waste, especially retrofitting additional tubes in existing buildings. According to the present invention grey and black water are conveyed in same tubing (78). After flushing a toilet basin (12a, 12b), the waste water is directed to a facility for black water (94). At other times the waste water is directed to a facility for grey water (84-88). This is achieved with a valve (30), which is controlled with a sensor units (20a, 20b) connected to toilet basins. The control is preferably wireless for easy installation, but it may also be wired. The system may also include a control unit (40) which monitors the functionality of the other units.

Description

SYSTEM AND METHOD FOR DISTINGUISHING BETWEEN GREY WATER AND

BLACK WATER

Field of invention

The invention relates to a system and a method for handling waste water. The invention is especially applicable for handling waste water in detached houses and leisure homes such as summer cottages.

Background technology

A considerable amount of waste water is produced in dwelling houses. Waste water from washing and bathing activities, for example, is called "grey water", and waste water from toilet basins is called "black water". In detached houses and leisure homes it has been common to convey the grey and black water via same tubing to e.g. a sedimentation basin outside the building. However, the environmental regulations have changed and the amount of allowed waste release into the environment has become smaller. A common solution for fulfilling the regulations is installing a costly purification package plant for the waste water processing. Alternatively, it would be possible to install separate tubing for grey and black waste water, and using a cesspit for the black water. However, especially in existing buildings it is quite difficult to install additional tubing, sometimes even impossible without substantial renovation work. And although it is possible to install separate tubing during the construction of a new building it causes additional costs.

Summary of the invention

The object of the invention is to provide a new solution for handling waste water of buildings, which fulfils environmental regulation, and which is possible to be implemented also in existing buildings without extensive installation work.

The object of the invention is achieved with a system for handling waste water produced in a building, the waste water comprising grey water and black water, wherein the system has a common tubing for conveying black and grey water, which system is characterised in that

- the system comprises a valve with at least one input and at least two outputs, an input coupled to said common tube conveying grey and black water, and a first output coupled to a facility for gray water, and a second output coupled to a facility for black water,

- said valve is controllable to convey the waste water received at the valve input selectably to the first output, being a first state of the valve, or to the second out- put of the valve, being a second state of the valve,

- the system comprises a sensor unit for detecting when a toilet basin of the building is flushed,

- based on detection of the sensor unit the controllable valve is adapted to convey the waste water received at the valve input to the second output.

The object is also achieved with a method for handling waste water produced in a building, the waste water comprising grey water and black water, wherein black and grey water are conveyed through the same tubing, which method is characterised in that

- waste water including grey and black water is conveyed to an input of a valve, which is controlled into first state wherein the waste is conveyed to a facility for grey water or into a second state wherein the waste water is conveyed to a facility for black water,

- flushing a toilet in the building is sensed, and

- the valve is controlled into the second state on the basis of sensing the flushing of a toilet.

Some preferable embodiments of the invention are described in dependent claims.

According to one embodiment of the invention the valve is controlled into the second state after a first predetermined delay has passed from the start of flushing a toilet basin. The value of the first delay may be based on the time it takes the black water to travel from the toilet basin to the valve.

According to one embodiment of the invention the valve is controlled back into a first state after a second determined delay has passed from flushing the toilet basin. The sensor of the sensor unit may be e.g. a flow sensor, a pressure sensor, vibration sensor or an acoustic sensor connected to the inlet tube of the toilet basin. Alternatively the sensor may be connected to the flushing lever of the toilet basin, whereby optical or movement sensors may be used, for example. Those sensors thus sense flowing of the inlet flushing water or actuating the flushing. It may also be possible to connect the sensor to the waste outlet of the toilet basin. In this case, pressure, vibration or acoustic sensors may be used, for example. Further, the sensor may be user actuated means, such as a press switch or a touch control switch, which is pressed/touched by the user just before or after flushing. Such a press switch can be installed on the wall, for example, beside the receiver/transmitter of the sensor unit.

In a preferred embodiment of the invention the valve is controlled in a wireless manner by transferring a short range radio signal between units of the system. The communication may thus follow e.g. Bluetooth, Zigbee, WLAN, WUSB, Wi- MAZ, Wibree or other alternative radio communications standards/protocols. It is also possible to use an existing mobile cellular telephone network for communication, such as 1 G, 2G, 3G, 4G etc. In such an implementation the sensor unit and the valve unit may include corresponding communication modules, and the sensor unit may send a short message (SMS), for example, to the valve unit in order to indicate flushing.

It is alternatively possible to use a wired control instead of wireless. The wiring can be led through the waste water tubing, or cable channels, for example. In such an implementation no radio receiver/transmitters or antennas are needed.

In a further embodiment control communication is based on ultrasound waves audio sound waves or infra sound waves. A sound wave transmitter of a sensor unit can be coupled to the waste water tubing as well as the sound wave receiver of the valve unit. The sound waves are thus conveyed along the tubing.

In a still further embodiment there is an acoustic sensor, such as a microphone, installed at the waste water tubing near to the controlling valve. The output signal of the acoustic sensor is monitored, and a sound of flushing a toilet arranged to be detected from the signal by using suitable signal filtering, for example. Upon detecting the sound of flushing toilet the waste valve is controlled into the second state. With this solution there is no need to use wired or wireless remote control transmitters/receivers, and there is no need to install sensors at the toilet. It is al- so possible to monitor flushing of several toilet basins with a single acoustic sensor installed at the waste water tubing. According to other some embodiments the valve unit may be installed at the facility for the black water. The valve unit may be attached on the facility or inside the facility. The temperature inside the facility always remains above zero degrees C, so installing the valve inside the facility for black water prevents the valve from freezing.

A simple implementation of the system according to the invention may comprise one or several sensor units and a valve unit, without other types of units. According to a further embodiment of the invention the system also has a control unit, which has means for communicating with one or several sensor units and a valve unit. The control unit is adapted to monitor the functionality of said other units, and to give an indication in case on non-functioning of any unit. It is also possible that the wireless control system is used for controlling other devices of a building in addition to the valve control, thus forming a larger control system in the build- ing.

It is preferable that the operating range of a wireless communication is sufficient for communicating between all sensor units and the valve unit. However, for situation where the operating range is not sufficient, an embodiment of the invention can be used wherein the system comprises at least one repeater unit. The repeater unit has means for receiving information from one or several sensor units, and means for forwarding said information to the valve unit. The repeater is useful in installations where the operating range of the radio communications is not sufficient between the installed units. In one further embodiment of the invention a control unit of the system also serves as a repeater. It is also possible that a sensor unit serves as a repeater for another sensor unit. Repeaters are apparently not needed if a mobile cellular system is used for communication between sensor and valve units. The facility for grey water may be e.g. a combination of septic tanks followed by possible filtering and leaching field at the ground. The facility for black waste water may be e.g. a cesspit. The valve may be installed as a separate unit, but in a preferable embodiment it is installed inside or on the cesspit. By installing the valve inside or on the cesspit the valve can be prevented from freezing. This is because the cesspit is located at such a depth in the ground where temperature remains above zero degrees C. A cesspit usually has a manhole for servicing, and such a manhole can also be used for servicing the valve unit when the valve unit is installed inside or on the cesspit. If the valve unit is installed in a separate location, a small housing is required which has sufficient space for servicing the valve.

The inventive solution has significant advantages compared to the prior art. When the invention is applied it is not necessary to use separate tubing for grey and black waste. This is especially advantageous when existing buildings need to be renovated in accordance with the environmental standards. However, even in new buildings it is possible to reduce installation work of tubing. The solution according to the invention also a further advantage of avoiding an installation of a costly package plant.

The time periods when the valve is controlled to the second state are relatively short. Therefore, the amount of grey water entering the facility for black water is negligibly small. With the present invention it is also possible to avoid the black water from entering the facility for grey water, which is an important feature in view of environmental waste load.

The term "sensor" includes means that detect physical quantities, such as a pressure, flow or vibration sensor, and/or user actuation, such as a press switch.

List of drawings

In the following the invention is described with help of the enclosed drawings, in which:

Figure 1 illustrates a block diagram of an exemplary system according to the invention;

Figure 2 illustrates a block diagram of an exemplary sensor unit according to the invention;

Figure 3a illustrates a block diagram of an exemplary valve unit according to the invention; Figure 3b illustrates an exemplary controllable valve which can be used in implementing the invention; Figure 3c illustrates another exemplary controllable valve which can be used in implementing the invention;

Figure 4 illustrates a block diagram of an exemplary control unit according to the invention; and

Figure 5 illustrates a flow diagram of an exemplary method according to the invention.

Detailed description of embodiments

Figure 1 illustrates a block diagram of an exemplary system 10 according to the invention for handling waste water in a building 1 1 , which is a detached house or a leisure home. The building has several sources of grey water. A tub 16 has an outlet 76 for waste water. Basins 15a and 15b have outlets 75a and 75b respectively. Washing machine 17 has an outlet 77. There may naturally be further sources of grey water not shown in Figure 1 , such as sources in a kitchen. The grey water is led into a common tube 78, which leads to a controllable valve 30. The tubing has also an air ventilation pipe 79 led through the roof to the outside of the building.

In accordance with the present invention, the outlets of the black water sources are connected to the same tubing as the grey water sources. Toilet 12a is con- nected with tube 72a and toilet 12b is connected with tube 72b. Toilets 12a and 12b have sensor units 20a and 20b, respectively. The Figure also shows their antennas 23a and 23b for communication on radio waves. The sensor units have sensors for detecting the flushing of the toilet. When flushing is detected the sensor unit controls the valve unit with wireless control to change into state 2 where the waste water is conveyed via outlet 91 of the valve 30 to the facility for black water 94. It takes a certain time until the black water receives the valve, end therefore a corresponding or shorter delay may be applied between the start of flushing and the change of the valve to the second state. After controlling the valve to the second state, all waste water continues to flow to the facility for black water 94, which is a cesspit in this case. There is a second delay applied, which corresponds to the time the flushing normally lasts. The second delay may also be slightly longer. After the second time delay the valve re- turns to the first state, and all waste water then flows to the facility for grey water, which is a combination of two septic tanks 84 and 85, possible filter and a leaching field 88. The valve unit receives its operating power from mains voltage, whereby there is a mains connection 19 at the wall of the building and mains cabling 31 to the valve unit. Other units of the system may have chargeable or disposable batteries as a power source, or they may have a dc input for an external power supply, for example. It is also possible that the other units have an internal dc power supply, and the units can be directly connected to mains socket.

The system of Figure 1 also comprises a control unit (40). The control unit may communicate with sensor unit(s) and the valve unit, and monitor their operating status. If a unit is non-operational due to shortage of operating power, for exam- pie, the control unit may give an audible alarm signal, for example. The control unit may also receive information from the sensor units regarding the charge level of the batteries. The charge levels may then be shown at a display of the control unit. It may be possible that a control unit is also used for controlling other devices in a building.

It is further possible that the control communications between the sensor units and the valve unit is led via the control unit. The control unit may serve as a repeater, forwarding the data without processing, or the control unit may process the data before forwarding to the valve unit. It is also possible that the system in- eludes optional repeaters if the operating range of the radio communication is not sufficient between all units of the system.

The system of Figure 1 has a separately installed valve unit 30. According to other preferable embodiments the facility for black water, such as a cesspit, may be installed at the location of the valve unit 30 so that the valve unit is installed at the facility 94 for the black water. The valve unit may be attached on the facility or inside the facility. The temperature inside and on the facility 94 always remains above zero degrees C, so installing the valve inside or on the facility for black water prevents the valve from freezing. A cesspit usually has a manhole for servic- ing, and such a manhole can also be used for servicing the valve unit. If the valve unit is installed in a separate location, a small housing is required which has sufficient space for servicing the valve. Figure 2 illustrates a block diagram of an exemplary sensor unit 20 according to the invention. The sensor unit has a sensor 25 for sensing some physical property in order to detect flushing of a toilet. The sensor may be connected to the tube for incoming water of the toilet basin. In this case the sensor may be e.g. a flow me- ter, whereby the start of water flow in the tube is detected. It is also possible to use a vibration sensor or an acoustic sensor i.e. a microphone connected to the incoming tube in order to detect water flow. The sensor may also be a pressure sensor in the incoming water tube, whereby a decrease in the pressure is detected when flushing the toilet.

It is also possible to detect moving of a lever which is used in flushing the toilet. A sensor detecting the movement may be an optical sensor, accelerometer, proximity sensor or just an electrical switch connected to the lever. Further it is possible to detect the flushing by installing a sensor at the outlet tube of the toilet. Such a sensor may be e.g. a pressure sensor, vibration sensor, an acoustic sensor etc.

The sensor may also be user actuated means, such as a press switch. The user then actuates the press switch just before or after flushing the toilet. Such a press switch can be installed on the wall, for example, besides the receiver/transmitter of the sensor unit. Using a press switch as a sensor makes the sensor circuit simple to implement.

The signal of the sensor is read by a processor 26, which is preferably a microprocessor or a microcontroller. Depending on the type of the sensor and the processor, it may be necessary to amplify the sensor signal and/or to convert the signal to into digital mode. It may thus be necessary to use an amplifier and/or an A D converter between the sensor and the processor (not shown in the Figure).

The sensor unit communicates with the control unit and/or the valve unit in order to control the valve unit on the basis of the sensor signal. For this purpose the sensor unit has a receiver/transmitter 22 with an antenna 23. The wireless communication uses radio frequencies that are designated for short or medium range data transfer purposes. The communication may thus follow Bluetooth, Zigbee, WLAN, WUSB, WiMAZ or Wibree radio communications standards/protocols, for example. It is naturally possible that other alternative radio communication standards/protocols can be used. It is possible that the receiver/transmitter includes a separate processor for controlling communications, or it is possible that there is a common processor for controlling communications as well as other functions of the sensor unit.

The sensor unit also has a memory 27 for storing programs executed by the pro- cessor(s). The memory may also store parameters such as threshold values for sensor signals. For example, when the sensor signal exceeds such a predetermined threshold value, this can be interpreted as flushing. The sensor unit may also include an electrical connection, such as an USB connection, for storing programs or other data in the memory 27 of the sensor unit. It may also possible to store such data in a wireless manner via the receiver/transmitter. The units of the system preferably have an identification code which is used in communications in order to address a certain unit of the system. Such an identification code may also be stored to the memory 27. The sensor unit further includes a battery 29 for providing operating energy for the sensor unit. The battery may be disposable or chargeable. It is also possible that the sensor unit has a power connection for receiving operating power from a dc power supply connected to mains voltage. It is further possible that the sensor unit has an internal dc power supply receiving its power input from the mains volt- age. Such a sensor unit may have a mains plug with a cable or attached to its housing.

Figure 3a illustrates a block diagram of an exemplary valve unit 30 according to the invention. The valve unit communicates with the control unit and/or the sensor unit in order to receive control data. For this purpose the valve unit has a same type of a receiver/transmitter 32 with an antenna 33 as the other units of the system. The control data is further led to a processor 36, which controls the valve 35 according to the received control data. The valve unit may have separate processors for controlling communications and other functions of the valve unit, or a sin- gle processor may be used for both purposes.

The valve unit also has a memory 37 for storing programs executed by the processors). The memory may also store parameters such as delay values for controlling the valve. An identification code of the valve unit may also be stored to the memory 37. The valve unit may also include an electrical connection, such as an USB connection, for storing programs or other data in the memory 37 of the valve unit. It may also possible to store such data in a wireless manner via the receiver/transmitter. The valve 35 may be a three-way valve, which connects the input to either the first output or the second output according to electrical control. It is also possible that the valve 35 comprises two two-way valves; one valve between the input and the first output, and one valve between the input and the second output. The two valves are controlled in such a way that one of the valves is open and one of the valves is shut, depending on the desired state of the valve combination.

An electrically controllable valve normally includes an actuator, such as an elec- trie motor. It is possible that an amplifier or a relay is also required for driving the valve (not shown in the Figure).

The valve unit further includes power supply 39 for providing operating energy for the valve unit. It is preferred that the valve unit receives its operating power from mains, whereby the power supply of the valve unit converts the mains voltage into a suitable DC (direct current). Alternatively, the valve unit may include a chargeable or disposable battery.

Figure 3b illustrates a top view of an exemplary valve which can be used for im- plementing the invention. This valve is used inside or on a cesspit. The valve has a frame 354, which has connections for an input tube 78 and output tube 81 . The valve also has a turnable tube 356 inside the frame. The tube 356 is attached to the frame with a shaft 357 and articulating joints 358. This enables the tube 356 to turn between horizontal and vertical positions. The tube is turned with an electric motor 352. When the tube is in its horizontal position (first state) as shown in Figure 3b the waste water runs from the input tube through the turnable tube 356 to the output tube 81 for gray water. There are preferably seals 378, 381 between the input/output tubes and the turnable tube in order to prevent leaking of the waste water. When the valve is controlled to the second state the motor turns the turnable tube into vertical position. This way the black water from the input tube 78 drops down to the cesspit.

Figure 3c illustrates another exemplary valve which can be used for implementing the invention. The input tube 78 is connected to a flexible tube 378 of the valve. The opposite end of the flexible tube is can be turned between two positions with an electric motor 352. There is a shaft 353 between the motor and the tube for turning the tube. The valve also has a housing 355 , which directs the waste water, such as grey water, to an output tube 81 when the flexible tube is in its first position. When the flexible tube is in its second position the housing directs the waste water, such as black water, to the second output tube 91 .

Figure 4 illustrates a block diagram of an exemplary control unit 40 according to the invention. Such a control unit may be optional in a system according to the invention. The control unit communicates with the sensor unit(s) and the valve unit in a wireless manner. For this purpose the control unit has a same type of a receiver/transmitter 42 with an antenna 43 as the other units of the system. The control unit also has a processor 46 with a memory 47 with a program stored for the processor. The control unit may have separate processors and memories for controlling communications and other functions of the control unit / system, or a single processor and memory may be used for both purposes. The memory may also include stored parameter values, such as delay values or sensor threshold values. The control unit may then distribute the parameters to other units as re- quired. An identification code of the control unit may also be stored to the memory 47. The control unit may also include an electrical connection, such as an USB connection, for storing programs or other data in the memory 47 of the sensor unit. It may also possible to store such data in a wireless manner via the receiver/transmitter.

The control unit has a user interface 48, which preferably includes a display and possibly some user input means. The control unit shows the status of the system units on its display, for example. If some sensor unit or a valve unit is inoperative the control unit may also provide an audible alarm signal. In this case, the user in- terface may also include a buzzer, for example.

The control unit further includes a battery 49 for providing operating energy for the control unit. The battery may be disposable or chargeable. It is also possible that the sensor unit has a power connection for receiving operating power from a DC power supply connected to mains voltage. It is further possible that the control unit has an internal dc power supply receiving its power input from the mains voltage. Such a sensor unit may have a mains plug with a cable or attached to its housing. It is possible that the sensor units communicate directly with the valve unit, or it is possible that the sensor units communicate with the control unit, and the control unit forwards the required control data to the valve unit. When forwarding data to from the sensor unit(s) to the valve unit, the control unit may serve as a repeater or it may process the information received from the sensor unit and provide control data for the valve unit based on the processing. For example, the required delays in the valve control may be applied in the control unit or in the valve unit. If required for extending the operating range, the system may also have repeaters which do not have control functions.

Figure 5 illustrates a flow diagram of an exemplary method 50 for waste water handling according to the invention. In phase 51 the valve of the system is controlled into state 1 wherein the valve conveys the waste water to a facility for grey water. In phase 53 signal of the sensor unit is monitored, and it is detected whether toilet flushing is activated. As long as the flushing is not activated the valve is kept in state 1 , and the sensor is monitored.

When toilet flushing is detected in phase 55 the valve of the system is controlled into state 2 wherein the valve conveys the waste water to a facility for black water, phase 57. There may be a first delay applied after the flushing is activated until the valve is controlled to the state 2. The value of the first delay is based on the time it takes the black water to flow from the toilet basin to the valve. It is possible for example, to measure the flow time and to set the delay on the basis of the measured time value. The value of the first delay may also be substantially zero.

After the valve has been controlled to state 2, a second predetermined delay waited in phase 59 until the valve is controlled back into state 1 in phase 51 . The value of the second delay is based on the time how long the flushing of a toilet normally lasts. If the sensor of the sensor unit is installed in the flushing lever or in the outlet tube of the toilet basin it may also be possible to detect the moment when the flushing stops. The valve can then be controlled into the state 1 when e.g. a first delay has passed after the flushing is stopped. The purpose of the delays is to minimize the amount of grey water entering the cesspit of the black water, and to avoid black water from entering the facility for grey water.

Above, some embodiments of systems and devices according to the invention have been described. The functionality according to the invention is achieved with, in addition to the devices mentioned herein, by storing the programs, which relate to the inventive functions and which control the processor/processors, into the memories of the devices of the system. Programming measurement devices is known as such for a person skilled in the art, and he/she can implement the functions of the present invention on the basis of the description given here.

It must be noted that above only some embodiments of the solution according to the invention have been described. The principle of the invention can naturally be modified within the scope of protection determined by the patent claims, e.g. in details of implementation and areas of use.

For example, even if wireless communication has been described as a preferred type of communication, it is also possible to implement the invention with wired data transfer. The present invention is neither in any way restricted to the data transfer standards mentioned as examples.

The description of embodiments mention applying a predetermined first delay be- fore controlling a valve to a second state after flushing. However, it should be noted that it is also possible not to use such a delay, i.e. the first delay may have a zero value. In the above embodiments a second delay has been applied until the valve is controlled back to the first state. However, the moment of controlling the valve back to the first state may be determined also in other alternative ways instead of applying a predetermined second delay.

Claims

Patent claims

1 . A system (10) for handling waste water produced in buildings (1 1 ), the waste water comprising grey water and black water, wherein the system has a common tubing (72-78) for conveying black and grey water, characterised in that

- the system comprises a valve (30) with at least one input and at least two outputs, an input coupled to said common tube conveying grey and black water, and a first output coupled to a facility for gray water (84-88), and a second output coupled to a facility for black water (94),

- said valve is controllable to convey the waste water received at the valve input selectably to the first output (81 ), being a first state of the valve, or to the second output (91 ) of the valve, being a second state of the valve,

- the system comprises a sensor unit (20, 20a, 20b) for detecting when a toilet basin of the building is flushed,

- based on detection of the sensor unit (20, 20a, 20b) the controllable valve (30) is adapted to convey the waste water received at the valve input to the second output.

2. The system according to claim 1 , characterised in that the system has means for controlling the valve into the second state after a first predetermined delay has passed from the start of flushing the toilet basin.

3. The system according to claim 1 or 2, characterised in that the system is adapted to control the valve into a first state after a second determined delay has passed from flushing the toilet basin.

4. The system according to any previous claim, characterised in that the sensor unit comprises a pressure sensor, a flow sensor, a vibration sensor or an acoustic sensor connected to the water inlet tube or the black water outlet tube of the toilet basin for sensing the flushing of the toilet basin.

5. The system according to any preceding claim, characterised in that the sensor unit comprises an optical sensor, movement sensor or a proximity sensor for sensing the movement of flushing lever of the toilet basin.

6. The system according to any preceding claim, characterised in that the sensor unit comprises a user actuated switch for actuation by a user to indicate flushing of the toilet.

7. The system according to any preceding claim, characterised in that the system has means for controlling the valve wirelessly by transferring a radio signal between units of the system.

8. The system according to any preceding claim, characterised in that the system has a control unit (40), which has means for communicating with one or several sensor units and the valve unit, which control unit is adapted to monitor the functionality of said units and to give an indication in case on non-functioning of said unit.

9. The system according to any preceding claim, characterised in that the system comprises a repeater unit (40), which has means for receiving information from one or several sensor units, and means for forwarding said information to the valve unit.

10. The system according to claim 1 , characterised in that the sensor unit comprises an acoustic sensor, such as a microphone, installed at the waste water tubing near to the controlling valve, means for monitoring the output signal of the acoustic sensor, means for detecting a sound of flushing a toilet basin from the signal, and upon detecting the sound of flushing the controllable valve is adapted to convey the waste water received at the valve input to the second output.

1 1 . The system according to claim 1 , characterised in that the valve unit is in- stalled inside or on a cesspit for black water.

12. A method for handling waste water produced in a building, the waste water comprising grey water and black water, wherein black and grey water are conveyed through the same tubing, characterised in that

- waste water including grey and black water is conveyed to an input of a valve, which is controlled into first state (51 ) wherein the waste is conveyed to a facility for grey water or into a second state wherein the waste water is conveyed to a facility for black water,

- flushing a toilet in the building is sensed (53, 55), and

- the valve is controlled into the second state (57) on the basis of sensing the flushing of a toilet.

13. The method according to claim 12, characterised in that the valve is controlled into the second state after a first predetermined delay has passed from the start of flushing the toilet basin.

14. The method according to claim 12 or 13, characterised in that the valve is controlled into a first state after a second determined delay has passed from flushing the toilet basin (59).

15. The method according to any of claims 12-14, characterised in that pres- sure, flow, vibration or acoustic sound is sensed from the water inlet tube or the black water outlet tube of the toilet basin in order to sense the flushing of the toilet basin.

16. The method according to claim 12, characterised in that acoustic sound is sensed from the waste water tubing near to the control valve in order to sense the flushing of the toilet basin.

17. The method according to any of claims 12-16, characterised in that movement of flushing lever of the toilet basin is sensed for indicating the flushing of the toilet basin.

18. The method according to any of claims 12-17, characterised in that a sensor actuated by a user is sensed for indicating the flushing of the toilet basin.

19. The method according to any of claims 12-18, characterised in that the valve is controlled wirelessly.

20. The method according to any of claims 12-19, characterised in that the functionality of the sensor unit and/or the valve unit is monitored by a control unit.

21. The method according to any of claims 12-19, characterised in that information transmitted from the sensor unit is forwarded to the valve unit by a repeater unit.