A system for detecting running water in a local water installation

Abstract

The invention relates to a system (100) for detecting water activity of a local water installation (250) in a building. The system comprises: a water inlet pipe (240) for supplying water to a local water installation (250) in a building, the water inlet pipe 5 (240) comprising an outer surface area being exposed to ambient conditions within a space (260) of the building; one or more temperature sensors (235) mounted on or engaging with said outer surface area of the water inlet pipe (240) being configured to detect a temperature (T1) of said outer surface area of the water inlet pipe (240); one or more temperature sensors (236) measuring the ambient temperature (T2) 10 within the space (260) of the building; an accelerometer (241) arranged in a position on the water inlet pipe (240) for detecting vibration signals (VS); and a computing unit arranged and configured to calculate a change in the temperature difference between T1 and T2, whereby the amount of running water of the local water installation (250) is estimated during a predefined time period, and arranged and 15 configured to apply the vibration signals of the accelerometer (241) for validating if the change in the temperature difference between T1 and T2 is caused by running water in the predefined time period.

Description

[0001] A SYSTEM FOR DETECTING RUNNING WATER IN A LOCAL WATER INSTALLATION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of systems and methods for detecting water activity in local water installations, such as running water from water taps or toilets in bathrooms that are unintentionally leaking. Also, the systems and methods are useful for identification of activity of water installations, such as use of water taps or toilet flush.

[0004] BACKGROUND OF THE INVENTION

[0005] Toilet leaks are the most common water waster in buildings. It is very surprising how much water can flow through a toilet or other installations without being noticed.

[0006] The hard part is that leaks in a toilet is difficult to detect. One of such leaking situations include intermittent toilets, i.e., toilets that leaks on and off due to limescale in the water. A running toilet can typically leak more than 10 liters / hour.

[0007] Different systems and methods have been described in the prior art for measuring water leakage. Common to these is that they are either unable to measure low amounts of water running in local installations or too unprecise when applied as stand-alone solutions.

[0008] US 9911307 Bl discloses a water leak alarm assembly and a method for identifying a water leak in a toilet includes a first housing that is mounted to a tank of a toilet. An alert unit is positioned within the first housing and the alert unit selectively generates an audible alarm. A second housing is provided and the second housing is positioned on a fluid supply line on the toilet. A detection unit is positioned within the second housing to detect the sound of water flowing through the fluid supply line. The detection unit is electrically coupled to the alert unit. The alert unit emits the audible alarm when the detection unit detects the sound of water flowing through the fluid supply line for a duration of time that exceeds a trigger duration of time. Using this solution, however, introduces the risk of generating a false alarm if the sound level in the area surrounding the toilet is above a certain level.

[0009] Accordingly, there is a need for a method and a system that is capable of detecting a leakage flow of a local water installation, such as a toilet, that is installed and being used on a regular basis and in which the disadvantage of the prior art solutions can be avoided.

[0010] DESCRIPTION OF THE INVENTION

[0011] Accordingly, there is provided a system (100) for detecting activity of a liquid of a local water installation (250) in a building, such as leaking water, the system (100) comprising: a water inlet pipe (240) for supplying water to a local water installation (250) in a building, the water inlet pipe (240) comprising an outer surface area being exposed to ambient conditions within a space (260) of the building; one or more temperature sensors (235) mounted on or engaging with said outer surface area of the water inlet pipe (240) being configured to detect a temperature (Tl) of said outer surface area of the water inlet pipe (240); one or more temperature sensors (236) measuring the ambient temperature (T2) within the space (260) of the building; an accelerometer (241) arranged in a position on the water inlet pipe

[0012] (240) for detecting vibration signals (VS); and a computing unit arranged and configured to calculate a change in the temperature difference between Tl and T2, whereby the amount of running water of the local water installation (250) is estimated during a predefined time period, and arranged and configured to apply the vibration signals of the accelerometer

[0013] (241) for validating if the change in the temperature difference between Tl and T2 is caused by running water in the predefined time period. In the present context, “ambient conditions” is intended to mean conditions inside a room of a building, where the local installation is installed. Accordingly, the outer surface area of the water inlet pipe is intended to being exposed to air within the room and localized within the room, such as in closets, behind wall-mounted toilets or fully exposed to the air within the room. “Ambient conditions” is not intended to be behind or inside walls without access to air , within isolation of the building or the like.

[0014] Typically, in temperate environments with a temperate of around 20 Degree Celsius within a building, the system may be allowed to detect a water leakage in cold water supply by comparing T1 with T2, such as if the cold water is significantly below 20 Degree Celsius. Likewise, the system may be allowed to detect a water leakage in hot water supply by comparing T1 with T2, such as if the hot water is significantly above 20 Degree Celsius. According to the invention, the accelerometer may be applied to validate a water leakage, such as if the outer surface is present in a closet or the like, where T1 remains below or above T2 for a certain period of time. Other situations may apply depending on the exact location of the temperature sensors or other factors. However, while the accelerometer may be applied for validation purposes, it is too unprecise for measurement of leakage of a low amount of water as a function of time. Also, vibrations may also be detected with uncertainty if the material of a water supply pipe is different from time to time.

[0015] The system offers a surprisingly high precision in detecting leakage of water and especially the amount of water leaked. The system has been seen to be much more precise than systems, where only an accelerometer is applied. Form an economic perspective, even if only a minor flow of water is leaked as a function of time, this may result in a high amount of water or even in some cases give rise to damage if the leakage is localized outside drainage zones, such as in closest or the like. The combination of the temperature measurements of the present invention with an accelerometer is considered to be a huge step towards filling the gap between the existing solutions in the market and the demands from customers. The sensor is designed to work at room temperature above 20 Degree Celsius but is also able to detect frozen and bursting pipes. Due to the mass of water and pipe, the change of temperature is slow and can take hours before a leakage is detected, but cold water running in the pipe constantly will change the temperature of the pipe significantly. Under normal condition where no water is running in the pipe, the temperature is about the same as ambient. To be able to detect a water leak it is necessary that the water temperature is above 2 Degree Celsius below the ambient temperature.

[0016] For a toilet which is not in use, the water in the pipe will typical be about the ambient temperature, i.e. the temperature in the room of the installation. When the toilet flushes, the tank and mechanism start to fill up the tank again. To fill the tank with 4 to 5 liters, will tack about 2 to 5 minutes and the tank supply pipe is cooled fast down. After the tank is flushed out, the tank is filled up and the temperature on the supply pipe will start rising. If the temperature continues rising and reaches the ambient temperature, the toilet is in good condition.

[0017] One of a series of critical factors of water quality is absence of bacteria, such as Legionella species. By detecting the temperature T1 according to the invention, an alert may be triggered if the conditions in the water may allow bacteria growth.

[0018] The accelerometer according to the invention is arranged in a position, in which vibration signals can be detected caused by water flowing through the inlet pipe or through a water cistern of a toilet. Validation of the temperature difference in the system may be advantageous to perform in certain situations, which is accommodated by the accelerometer according to the invention. Such as situation may be in building with exposed water pipes to ambient temperatures, where water is transferred over long distiances without or with minimal change in the water pipe temperature. In one embodiment, the accelerometer comprises a single-axis accelerometer. In one embodiment, the accelerometer comprises a two-axis accelerometer. In one embodiment, the accelerometer comprises a three-axis accelerometer. In one embodiment, the accelerometer comprises one or more piezoelectric accelerometers configured to sense vibration.

[0019] In one embodiment, the computer unit is arranged and configured to determine when no vibration amplitude below a predefined amplitude level, such as corresponding to a water flow of 5-1000 ml / min, has been detected by the accelerometer in a predefined time period.

[0020] In one embodiment, the computer unit is arranged and configured to determine when no vibration amplitude below a predefined amplitude level, such as corresponding to a water flow of 10-500 ml / min, has been detected by the accelerometer in a predefined time period.

[0021] In one embodiment, the computer unit is arranged and configured to determine when no vibration amplitude below a predefined amplitude level, such as corresponding to a water flow of 15-300 ml / min, has been detected by the accelerometer in a predefined time period.

[0022] In one embodiment, the computer unit is arranged and configured to determine when no vibration amplitude below a predefined amplitude level, such as corresponding to a water flow of 25-200 ml / min, has been detected by the accelerometer in a predefined time period.

[0023] In one embodiment, the computer unit is arranged and configured to determine when no vibration amplitude below a predefined amplitude level, such as corresponding to a water flow of 30-100 ml / min, has been detected by the accelerometer in a predefined time period. In one embodiment, the predefined time period is 10-600 minutes. In one embodiment, the predefined time period is 15-450 minutes. In one embodiment, the predefined time period is 30-300 minutes. In one embodiment, the predefined time period is 60-250 minutes. In one embodiment, the sensor comprises a setting unit, by which the predefined time period (AT) and / or the predefined amplitude level can be set and / or changed. Hereby, it is possible to set or change the predefined time period and / or the predefined amplitude level.

[0024] In one embodiment, the vibration sensor is attached to the outer surface of the inlet pipe. This position has been found to provide reliable data that can be used to detect a leakage flow. By determining when no vibration signals below a predefined amplitude level has been detected by the vibration sensor in a predefined time period, it is possible to determine if a leakage flow is present.

[0025] In one embodiment, the computer unit is arranged and configured to determine when a vibration amplitude above a predefined amplitude level has been detected by the accelerometer in a predefined time period. This use of the accelerometer is presently preferred compared to the use of measuring vibration below a certain amplitude, such as in situations where a low level leakage is present.

[0026] Especially, in combination with the temperature sensors according to the invention, this use surprisingly increases the precision of the present invention. For instance, very low leaks may be validated by the accelerometer according to the invention in combination with the temperature sensors. Leaks of only a low amount of water cannot be measured by a stand-alone accelerometer. Also, measurements above a certain amplitude is considered to further improve the solutions of the prior art.

[0027] It is to be understood that that the elements of the system and method of the present invention may be communicable coupled to each other. Especially, the temperature sensors, accelerometers and computing unit may be communicable coupled. In the present context, “communicably coupled” is intended to mean that the elements may be wirelessly coupled or coupled by wires. In case of wirelessly coupling, standards such as Bluetooth, Wi-Fi or Wireless MBus technology may be applied.

[0028] Additionally, the computing unit may be situated locally or may be cloud-based, i.e., it may be located in a distance to the local water installation.

[0029] In one embodiment, the amount of running water of the local water installation (250) is estimated for water leaks of down to 2 liter per hour. In one embodiment, the amount of running water of the local water installation (250) is estimated for water leaks of down to 3 liter per hour. In one embodiment, the amount of running water of the local water installation (250) is estimated for water leaks of down to 4 liter per hour. In one embodiment, the amount of running water of the local water installation (250) is estimated for water leaks of down to 5 liter per hour. In one embodiment, the amount of running water of the local water installation (250) is estimated for water leaks of down to 6 liter per hour. In one embodiment, the amount of running water of the local water installation (250) is estimated for water leaks of down to 10 liter per hour.

[0030] In one embodiment, the change in the temperature difference between T1 and T2 is at least 1 Degree Celsius. In one embodiment, the change in the temperature difference between T1 and T2 is at least 2 Degree Celsius. In one embodiment, the change in the temperature difference between T1 and T2 is at least 3 Degree Celsius. In one embodiment, the change in the temperature difference between T1 and T2 is between 1 and 2 Degree Celsius. In one embodiment, the change in the temperature difference between T1 and T2 is between 1 and 3 Degree Celsius. In one embodiment, the change in the temperature difference between T1 and T2 is between 2 and 4 Degree Celsius.

[0031] In one embodiment, the vibration signals of the accelerometer for validating if the change in the temperature difference between T1 and T2 is applied under conditions where the temperature of the water supplied in the water inlet pipe (240) is close to T1 and / or T2, such as less than 0.5 Degree Celsius difference. In one embodiment, the vibration signals of the accelerometer for validating if the change in the temperature difference between T1 and T2 is applied under conditions where the temperature of the water supplied in the water inlet pipe (240) is close to T1 and / or T2, such as less than 1 Degree Celsius difference.

[0032] In one embodiment, the vibration signals of the accelerometer for validating if the change in the temperature difference between T1 and T2 is applied under conditions where the temperature of the water supplied in the water inlet pipe (240) is close to T1 and / or T2, such as less than 2 Degree Celsius difference.

[0033] In one embodiment, the predefined time period is 24 hours. In one embodiment, the predefined time period is 18 hours. In one embodiment, the predefined time period is 12 hours. In one embodiment, the predefined time period is 6 hours. In one embodiment, the predefined time period is 3 hours. In one embodiment, the predefined time period is 1 hour.

[0034] In one embodiment, an alert is triggered for water leaks below 10 liter per hour for more than 24 hours. In one embodiment, an alert is triggered for water leaks below 5 liter per hour for more than 24 hours. In one embodiment, an alert is triggered for water leaks below 4 liter per hour for more than 24 hours. In one embodiment, an alert is triggered for water leaks below 3 liter per hour for more than 24 hours. In one embodiment, an alert is triggered for water leaks below 2 liter per hour for more than 24 hours. In one embodiment, an alert is triggered for water leaks below 1 liter per hour for more than 24 hours.

[0035] In context of the present invention, an “alert” is intended to mean a warning of an unusual state of water activity. An “alert” may be a notification in a central data system, a notification on a phone, a warning sound locally in the device of the local installation or delocalized, such as a warning sound on a phone. An “alert” may be triggered in various situations, such as leakage, stagnant water, events of use of local installations, unusual events, etc.

[0036] In the present context, “water activity” is to be understood as covering both “water leakage” or “events”, such as stagnant water, water flushs or events of use of local installations, including unusual usage of toilets, water tabs, etc.

[0037] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 1.2 Degree Celsius for more than 24 hours.

[0038] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 1.0 Degree Celsius for more than 24 hours.

[0039] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 0.8 Degree Celsius for more than 24 hours.

[0040] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 0.6 Degree Celsius for more than 24 hours.

[0041] In one embodiment, wherein an alert is triggered for water leaks above 2 liter per hour for more than 1 hour.

[0042] In one embodiment, wherein an alert is triggered for water leaks above 4 liter per hour for more than 1 hour.

[0043] In one embodiment, wherein an alert is triggered for water leaks above 6 liter per hour for more than 1 hour. In one embodiment, wherein an alert is triggered for water leaks above 8 liter per hour for more than 1 hour.

[0044] In one embodiment, wherein an alert is triggered for water leaks above 10 liter per hour for more than 1 hour.

[0045] In one embodiment, wherein an alert is triggered for water leaks above 15 liter per hour for more than 1 hour.

[0046] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 5 Degree Celsius for more than 1 hour.

[0047] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 4 Degree Celsius for more than 1 hour.

[0048] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 3 Degree Celsius for more than 1 hour.

[0049] In one embodiment, an alert is triggered when the change in the temperature difference between T1 and T2 is more than 2 Degree Celsius for more than 1 hour.

[0050] In one embodiment, an alert is triggered if T1 remains above 20 Degree Celsius remains above 20 Degree Celsius and below 60 Degree Celsius for a predetermined time period in order to detect presence of Legionella in order to detect presence of Legionella.

[0051] In one embodiment, an alert is triggered if T1 remains above 20 Degree Celsius remains above 20 Degree Celsius and below 60 Degree Celsius for a time period of 24 hours in order to detect presence of Legionella in order to detect presence of Legionella. In one embodiment, an alert is triggered if T1 remains above 20 Degree Celsius remains above 20 Degree Celsius and below 60 Degree Celsius for a time period of 2 days in order to detect presence of Legionella in order to detect presence of Legionella.

[0052] In one embodiment, an alert is triggered if T1 remains above 20 Degree Celsius remains above 20 Degree Celsius and below 60 Degree Celsius for a time period of 3 days in order to detect presence of Legionella in order to detect presence of Legionella.

[0053] In one embodiment, an alert is triggered if T1 remains above 20 Degree Celsius remains above 20 Degree Celsius and below 60 Degree Celsius for a time period of 7 days in order to detect presence of Legionella in order to detect presence of Legionella.

[0054] In one embodiment, an alert is triggered if T1 remains above 20 Degree Celsius remains above 20 Degree Celsius and below 60 Degree Celsius for a time period of 14 days in order to detect presence of Legionella in order to detect presence of Legionella.

[0055] In one embodiment, an alert is triggered if T1 remains above 20 Degree Celsius and below 55 Degree Celsius, such as above 50 Degree Celsius, such as above 45 Degree Celsius for any one of the predetermined time periods above.

[0056] In another aspect of the invention, there is provided a method of detecting a leakage of a local water installation (250) in a building, the method (100) comprising: providing a water inlet pipe (240) for supplying water to a local water installation (250) in a building, the water inlet pipe (240) comprising an outer surface area being exposed to ambient conditions within a space (260) of the building; detecting a temperature (Tl) of said outer surface area of the water inlet pipe (240) by one or more temperature sensors (235) mounted on or engaging with said outer surface area of the water inlet pipe (240); measuring the ambient temperature (T2) within the space (260) of the building by one or more temperature sensors (236); detecting vibration signals (VS) by an accelerometer arranged in a position on the water inlet pipe (240); and calculating a change in the temperature difference between T1 and T2 by a computing unit, whereby the amount of running water of the local water installation (250) is estimated during a predefined time period, and validating if the change in the temperature difference between T1 and T2 is caused by running water in the predefined time period by vibration signals of the accelerometer.

[0057] The method according to the invention may be combined with the embodiments of the system of the invention.

[0058] Referring now to Fig. 1 there is provided one example of the function of the temperature measurements according to the invention with different alert zones. One for high leaks (lowest part of the figure, one for low leaks (middle part of the figure) and one for free zone, where the temperature difference is below 1.2 Degree Celsius. Three curves are presented.

[0059] The system can be illustrated for an ambient temperature at 23 Degree Celsius (curve 1). In this example, the water temperature is 13,5 Degree Celsius at the start but increases over the test time to 17 Degree Celsius.

[0060] 1. At the starting point the flow of cold water is 201 / h. The temperature at the pipe drops very fast to 13,5 Celsius. See curve 1 in Fig 1 decreasing further below marking 1 on the x-axis.

[0061] 2. The water flow continues with 20 1 / h which keeps the temperature steady low. See curve 1 in Fig 1 ending with marking 2 on the x-axis. 3. The flow is changed to 4 1 / h. The temperature is rising to 15,5 Degree Celsius. The temperature is changing a bit as the water temperature is rising over the test time. See curve 1 in Fig 1 ending with -7 Degree Celsius on the y-axis.

[0062] 4. The water flow is closed, and the temperature is rising. The temperature will reach the ambient temperature if there is no water leak. See curve 1 in Fig 1 ending with -0 Degree Celsius on the y-axis.

[0063] 5. The water flow at 4 1 / h is started again. The temperature is dropping but in a slow speed than with a higher water flow. See curve 3 in Fig 1.

[0064] Referring to Fig 1, the algorithm is split up in 11 junction points (dots on curves 1-3), where action will take place. As long the temperature is in the direction of the Free zone, all type of action will be reset when crossing the Free zone line. If the temperature crosses the low leak line and into the low leak zone, the 24 hours timer is enabled. If the temperature continues to drop to high leak zone, the 1 hour’s timer is enabled (high leaks). If the temperature changes direction and go against ambient, both timer is on hold. If the temperature is not crossing the low leak line after 1 hour the timer will expire and an alert for high leak occur. If the temperature crosses the Low leak zone the 1-hour timer is reset and if the temperature continues rising and crosses the free zone each timer is in reset state.

[0065] In the coordinate system there are three examples of different events:

[0066] 1. The first example is a normal toilet flushes, where the temperature drops very fast and crossing both the LLZ and HLZ (curve 1). Each alert timer is now enabled, after the temperature is stabilized, the temperature is start rising. The timer is on hold as long the temperature is rising and after a while the temperature reach FZ and the timer is in reset state. 2. Example two, is behaving as a normal flush and each timer is enabled (curve 2). This time the temperature is rising very slowly but stabilizing in the HLZ area. After one hour the alert timer expire and start the alert sequence.

[0067] 3. Example three show a situation that is independent of the flush event and can occur any time (curve 3). The toilet is starting to leak very slowly. The temperature is dropping and stabilizing in the LLZ area. If the temperature don't rise to FZ before the 24 hours the timer is expire an alert occur.

[0068] Fig. 2 illustrates a toilet with an arrangement according to the invention. An inlet pipe provides water to a toilet and the temperature sensor for measuring T1 and the accelerometer is located on the inlet pipe fully exposed to ambient conditions in a room of a building. The inlet pipe may be of metal, plastic, rubber or the like, and is less dependent on the material of the inlet pipe compared to the accelerometer according to the invention. The sensors are communicably coupled to a computing device.

[0069] Fig 3 illustrates more details of the system according to the invention. Here, it can be seen that the sensors are tightly mounted on an inlet pipe of a local installation.

[0070] Fig 4 illustrates a water zink with two inlet pipes, one for hot water and one for cold water. Both supplies are provided with sensors for measurement of T1 and an accelerometer. The water supply pipes are made of a metal.

[0071] Fig 5 illustrates another location of the sensors and the accelerometer.

[0072] Fig 6 illustrates location of the sensors and the accelerometer within a box of a wall in a room of a building.

Claims

CLAIMS1. A system (100) for detecting water activity of a local water installation (250) in a building, the system (100) comprising: a water inlet pipe (240) for supplying water to a local water installation (250) in a building, the water inlet pipe (240) comprising an outer surface area being exposed to ambient conditions within a space (260) of the building; one or more temperature sensors (235) mounted on or engaging with said outer surface area of the water inlet pipe (240) being configured to detect a temperature (Tl) of said outer surface area of the water inlet pipe (240); one or more temperature sensors (236) measuring the ambient temperature (T2) within the space (260) of the building; an accelerometer (241) arranged in a position on the water inlet pipe(240) for detecting vibration signals (VS); and a computing unit arranged and configured to calculate a change in the temperature difference between Tl and T2, whereby the amount of running water of the local water installation (250) is estimated during a predefined time period, and arranged and configured to apply the vibration signals of the accelerometer(241) for validating if the change in the temperature difference between Tl and T2 is caused by running water in the predefined time period.

2. The system according to claim 1, wherein the computer unit is arranged and configured to determine when no vibration amplitude below a predefined amplitude level, such as corresponding to a water flow of 5-1000 ml / min, has been detected by the accelerometer in a predefined time period.

3. The system according to claim 1 or 2, wherein the computer unit is arranged and configured to determine when a vibration amplitude above a predefined amplitude level has been detected by the accelerometer in a predefined time period.

4. The system according to any one of the preceding claims, wherein the amount of running water of the local water installation (250) is estimated for water leaks of down to 3 liter per hour.

5. The system according to any one of the preceding claims, wherein the change in the temperature difference between T1 and T2 is at least 2 Degree Celsius.

6. The system according to any one of the preceding claims, wherein the vibration signals of the accelerometer for validating if the change in the temperature difference between T1 and T2 is applied under conditions where the temperature of the water supplied in the water inlet pipe (240) is close to T1 and / or T2, such as less than 1 Degree Celsius difference.

7. The system according to any one of the preceding claims, wherein the predefined time period is 24 hours.

8. The system according to any one of the preceding claims, wherein an alert is triggered for water leaks below 5 liter per hour for more than 24 hours.

9. The system according to any one of the preceding claims, wherein an alert is triggered when the change in the temperature difference between T1 and T2 is more than 1.2 Degree Celsius for more than 24 hours.

10. The system according to any one of the preceding claims, wherein an alert is triggered for water leaks above 10 liter per hour for more than 1 hour.

11. The system according to any one of the preceding claims, wherein an alert is triggered when the change in the temperature difference between T1 and T2 is more than 5 Degree Celsius for more than 1 hour.

12. The system according to any one of the preceding claims, wherein the water activity is a water leakage.

13. The system according to any one of the preceding claims, wherein an alert is triggered if T1 remains above 20 Degree Celsius and below 60 Degree Celsius for a predetermined time period in order to detect presence of Legionella.

14. The system according to any one of the preceding claims, wherein an alert is triggered if T1 remains above 20 Degree Celsius and below 60 Degree Celsius for a time period of 1 day or more in order to detect presence of Legionella.

15. A method of detecting water activity of a local water installation (250) in a building, the method (100) comprising: providing a water inlet pipe (240) for supplying water to a local water installation (250) in a building, the water inlet pipe (240) comprising an outer surface area being exposed to ambient conditions within a space (260) of the building; detecting a temperature (Tl) of said outer surface area of the water inlet pipe (240) by one or more temperature sensors (235) mounted on or engaging with said outer surface area of the water inlet pipe (240); measuring the ambient temperature (T2) within the space (260) of the building by one or more temperature sensors (236); detecting vibration signals (VS) by an accelerometer (241) arranged in a position on the water inlet pipe (240); and calculating a change in the temperature difference between Tl and T2 by a computing unit, whereby the amount of running water of the local water installation (250) is estimated during a predefined time period, and validating if the change in the temperature difference between Tl and T2 is caused by running water in the predefined time period by vibration signals of the accelerometer(241 ) .

16. The method according to claim 15 as defined in any one of claims 2-14.

Images