WATER AND A METHOD FOR SUCH RECYCLING

Technical field

The present invention relates to the field of water recycling. More specifically, the invention relates to a water distribution system for enabling recycling of water.

Background of the invention

Fresh water is a limited resource, which is becoming more and more scarce. Because of this, new and improved ways of saving water are constantly sought after.

There are two general ways of saving water. Either you can treat the water in order to be able to re-use it, or you can repurpose it. In the latter case, a well-known technique is to use water from e.g. a sink to flush a toilet, instead of using fresh water. However, there are limitations to these kind of systems. For instance, there may be a shortage of water available to the toilet, if not enough used water has been produced. Hence, there are improvements to be made within this field.

Summary of the invention

It is an object of the present inventive concept to mitigate, alleviate or eliminate at least one of the above-mentioned deficiencies in the art and disadvantages singly or in any combination and solve at least the above- mentioned problems.

The inventors of the present inventive concept have realized, since commonly there are more than one source of used water in a bathroom, that a system comprising two collection tanks may be advantageous in that the second collection tank can serve as a buffer for the first tank if it runs out of used water.

According to a first aspect, a water distribution system for enabling recycling of water is provided. The system comprising: a first water storage tank, wherein an inlet of the first water storage tank is fluidly connected to a drain of a first user unit and arranged to collect used water from the first user unit; a second water storage tank, wherein an inlet of the second storage tank is fluidly connected to a drain of a second user unit and arranged to collect used water from the second user unit; and a valve arrangement arranged to control the flow of the used water within the system; wherein an outlet of the first water storage tank is fluidly connected to a third user unit for supplying the third user unit with the used water stored in the first water storage tank; and wherein an outlet of the second water storage tank is fluidly connected to the first water storage tank for supplying the first water storage tank with the used water stored in the second water storage tank.

By the wording “user unit”, it is hereby meant any type of unit which uses water. The user unit may for instance be a water tap, a shower, a washing machine or a toilet. The first and second user units may be different user units. Thus, the first and second water storage tanks may be arranged to collect used water from two different user units.

The valve arrangement should be interpreted as a device configured to control the water flow within the system. The valve arrangement may comprise one or more parts. For instance, the valve arrangement may comprise one or more valves, and a control unit configured to control the valves.

A possible associated advantage is that the second water storage tank may function as a buffer to the first water tank. In other words, the second water storage tank may help to ensure a supply of used water to the third user unit, thereby facilitating an improved recycling of water.

The valve arrangement may be arranged such that the second water storage tank supplies water to the first water storage tank if a water level of the first water storage tank is below a predetermined threshold.

This allows the first water storage tank to always have a minimum amount of water which may be enough for a certain amount of usage of the third user unit.

By the wording “the valve arrangement being arranged such that...” (or similar) may be interpreted as “the control unit being configured to control the valve arrangement such that...”. In other words, the control unit may be configured to control the valve arrangement such that water may be supplied to the first water storage tank from the second water storage tank if the water level of the first water storage tank is below the predetermined threshold.

The system may further comprise a water discharging outlet. The water discharging outlet may allow water to be discarded, for instance to a drain. This may prevent the system from overflowing. It may further allow the system to discharge used water that is too dirty to recycle.

The system may further comprise a sensor arrangement arranged for measurement of at least one water quality parameter of the used water in the first water storage tank and/or the second water storage tank. The valve arrangement may be arranged to discharge water from the first water storage tank and/or the second water storage tank through the water discharging outlet if the at least one measured water quality parameter in the first and/or second water storage tank respectively is below a quality threshold. In other words, the control unit may be configured to control the valve arrangement such that water may be discharged from the first water storage tank and/or the second water storage tank through the water discharging outlet if the at least one measured water quality parameter in the first and/or second water storage tank respectively is below the quality threshold.

This may be advantageous in that water which is not suitable for reutilization may be discarded from the first and/or second water storage tanks.

The valve arrangement may be arranged to discharge water from the first water storage tank if the first water level is above a first overflow threshold and/or discharge water from the second water storage tank if the second water level is above a second overflow threshold. In other words, the control unit may be configured to control the valve arrangement such that water may be discharged from the first water storage tank if the first water level is above the first overflow threshold and/or discharge water from the second water storage tank if the second water level is above the second overflow threshold.

The first and second overflow thresholds may serve as overflowing protection. The outlet of the second water storage tank may be fluidly connected to the third user unit. The valve arrangement may be further arranged such that: water may be supplied to the third user unit from the first water storage tank if the water level of the first water storage tank is above the predetermined threshold, or water may be supplied to the third user unit from the second water storage tank if the water level of the first water storage tank is below the predetermined threshold. In other words, the control unit may be configured to control the valve arrangement such that water may be supplied to the third user unit from the first water storage tank if the water level of the first water storage tank is above the predetermined threshold, or such that water may be supplied to the third user unit from the second water storage tank if the water level of the first water storage tank is below the predetermined threshold.

This may allow the second water storage tank to bypass the first water storage tank and supply water directly to the third user unit. This may be advantageous for instance if the used water in the first water tank needs to be evaluated with regards to quality. Then water can instead be supplied from the second water storage tank directly.

The inlet of the first water storage tank may be fluidly connected to an external water supply. The valve arrangement may be arranged such that water from the external water supply may be supplied to the first water storage tank if the water level of the first water storage tank is below the predetermined threshold and a water level of the second water storage tank is below another predetermined threshold. In other words, the control unit may be configured to control the valve arrangement such that water from the external water supply may be supplied to the first water storage tank if the water level of the first water storage tank is below the predetermined threshold and a water level of the second water storage tank is below the another predetermined threshold.

This may be advantageous in case neither the first nor second water storage tank has enough used water to supply the third user unit.

The first user unit may be a sink.

The second user unit may be a washing machine.

The third user unit may be a toilet. The first water storage tank may have a first storage capacity and the second water storage tank may have a second storage capacity. The second storage capacity may be larger than the first storage capacity.

The second storage capacity may be two to four times larger than the first storage capacity.

The system may further comprise a pump for pressurizing the used water in the water distribution system. The pump may be part of the valve arrangement. The pump may be controlled by the control unit.

The system may further comprise a water treatment unit configured to treat the used water in the first water storage tank and/or the second water storage tank with regard to at least one water quality parameter.

The outlet of the second water storage tank may be fluidly connected to the third user unit, wherein the valve arrangement may further comprise a sensor arrangement arranged for measurement of at least one water quality parameter of the used water in the first water storage tank and/or the second water storage tank respectively. The valve arrangement may be arranged such that: if the at least one water quality parameter of the first water storage tank may be lower than the at least one water quality parameter of the second water storage tank: treating, by the water treatment unit, the used water in the first water storage tank, and supplying used water from the second water storage tank to the third user unit, or if the at least one water quality parameter of the first water storage tank may be higher than the at least one water quality parameter of the second water storage tank: treating, by the water treatment unit, the used water in the second water storage tank, and supplying used water from the first water storage tank to the third user unit.

In other words, the control unit may be configured to control the valve arrangement such that: if the at least one water quality parameter of the first water storage tank may be lower than the at least one water quality parameter of the second water storage tank: treating, by the water treatment unit, the used water in the first water storage tank, and supplying used water from the second water storage tank to the third user unit, or if the at least one water quality parameter of the first water storage tank may be higher than the at least one water quality parameter of the second water storage tank: treating, by the water treatment unit, the used water in the second water storage tank, and supplying used water from the first water storage tank to the third user unit.

This may be advantageous in that water may be treated in one of the water storage tanks without effecting the water supply to the third user unit.

According to a second aspect, a method for recycling of water in a water distribution system is provided. The water distribution system comprises: a first water storage tank, wherein an inlet of the first water storage tank is fluidly connected to a drain of a first user unit; a second water storage tank, wherein an inlet of the second storage tank is fluidly connected to a drain of a second user unit; and a valve arrangement arranged to control the flow of the used water within the system; wherein an outlet of the first water storage tank is fluidly connected to a third user unit; and wherein an outlet of the second water storage tank is fluidly connected to the first water storage tank. The method comprising: collecting used water from the first user unit in the first water storage tank; collecting used water from the second user unit in the second water storage tank; supplying, by use of the valve arrangement, used water from the first water storage tank to the third user unit for recycling; and supplying, by use of the valve arrangement, used water from the second water storage tank to the first water storage tank. The steps of the method may be performed by a control unit as further described above in connection with the first aspect. The steps may be performed by the control unit in the sense that the control unit sends instructions to other components of the water distribution system, such as the valve arrangement.

Supplying used water from the second water storage tank to the first water storage tank may be performed in response to a water level of the first water storage tank being below a predetermined threshold.

The water distribution system may further comprise a water discharging outlet and one or more sensor units. The method may further comprise: determining at least one water quality measure of the used water in the first water storage tank and/or in the second water storage tank; in response to the at least one measured water quality parameter in the first and/or second water storage tank being below a quality threshold, discharging, by use of the valve arrangement, water from the first water storage tank and/or the second water storage tank respectively through the water discharging outlet.

The outlet of the second water storage tank may be fluidly connected to the third user unit. Supplying used water from the first water storage tank to the third user unit may be performed in response to the water level of the first water storage tank being above a predetermined threshold. The method may further comprise: in response to the water level of the first water storage tank being below the predetermined threshold, supplying, by use of the valve arrangement, water from the second water storage tank to the third user unit.

The inlet of the first water storage tank may be fluidly connected to an external water supply. The method may further comprise: in response to the water level of the first water storage tank being below the predetermined threshold and a water level of the second water storage tank being below another predetermined threshold, supplying, by the valve arrangement, water from the external water supply to the first storage tank.

The above-mentioned features of the first aspect, when applicable, apply to this second aspect as well. In order to avoid undue repetition, reference is made to the above.

A further scope of applicability of the present disclosure will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred variants of the present inventive concept, are given by way of illustration only, since various changes and modifications within the scope of the inventive concept will become apparent to those skilled in the art from this detailed description.

Hence, it is to be understood that this inventive concept is not limited to the particular steps of the methods described or component parts of the systems described as such method and system may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in the specification and the appended claim, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to “a device” or “the device” may include several devices, and the like. Furthermore, the words “comprising”, “including”, “containing” and similar wordings do not exclude other elements or steps.

Brief description of the drawings

The above and other aspects of the present inventive concept will now be described in more detail, with reference to appended drawings showing variants of the present inventive concept. The figures should not be considered limiting the invention to the specific variant; instead, they are used for explaining and understanding the inventive concept.

As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of variants of the present inventive concept. Like reference numerals refer to like elements throughout.

Figure 1 schematically illustrates, by way of a first example, a water distribution system for enabling recycling of water.

Figure 2 schematically illustrates, by way of a second example, a water distribution system for enabling recycling of water.

Figure 3a-3c are flow charts illustrating the step of a method for recycling of water in a water distribution system.

Detailed description

The present inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred variants of the inventive concept are shown. This inventive concept may, however, be implemented in many different forms and should not be construed as limited to the variants set forth herein; rather, these variants are provided for thoroughness and completeness, and fully convey the scope of the present inventive concept to the skilled person. A water distribution system for enabling recycling of water, as well as a method for recycling of water in a water distribution system will be described with reference to Fig. 1 to Fig. 3a.

Figure 1 illustrates, by way of a first example, the water distribution system 100 for enabling recycling of water, also referred to as the system.

The system 100 comprises a first water storage tank 102. An inlet of the first water storage tank 102 is fluidly connected to a drain of a first user unit 104. The first water storage tank 102 is arranged to collect used water from the first user unit 104. The used water collected in the first water storage tank 102 may later on be used in a third user unit 110. In other words, the used water from the first user unit 104 may be collected and stored in the first water storage tank 102 until it can be reutilized in the third user unit 110.

The system 100 further comprises a second water storage tank 106. An inlet of the second water storage tank 106 is fluidly connected to a drain of a second user unit 108. The second user unit 108 may be a different user unit than the first user unit 104. The second water storage tank 106 is arranged to collect used water from the second user unit 104. The used water collected in the second water storage tank 106 may later on be used in the third user unit 110. The used water from the second user unit 108 may be collected and stored in the second water storage tank 106 until it can be supplied to the first water storage tank 102 or to the third user unit 110. In the illustrated example of Fig. 1 , the second water storage tank 106 may be a water tank in its simplest form. As will become apparent below, the first water storage tank 102 may comprise additional components, such as sensors and overflow protection. This allows for a simple and cost effective system having few technical components. In other words, the intelligence in the system may be provided in the first water storage tank 102 such that the second water storage tank 106 may be only a simple water tank.

An outlet of the first water storage tank 102 is fluidly connected to the third user unit 110 for supplying the third user unit 110 with the used water stored in the first storage tank 102. An outlet of the second water storage tank 106 is fluidly connected to the first water storage tank 102 for supplying the first water storage tank 102 with the used water stored in the second water storage tank 106.

The system 100 further comprises a valve arrangement 112. The valve arrangement 112 may be arranged to control the flow of the used water within the system 100. The valve arrangement 112 may comprise one or more valves. In the present example the valve arrangement 112 comprises a first valve 112a, a second valve 112b and a third valve 112c. However, as is readily understood by the skilled person, the valve arrangement 112 may comprise any number of valves, as well as other components commonly used to control the water flow in a water distribution system. Further, the valves may be of different types, e.g. check valves, gate valves, ball valves and pneumatically-actuated valves.

The valve arrangement 112 may be arranged such that the second water storage tank 106 may supply water to the first water storage tank 102 if a water level of the first water storage tank 102 is below a predetermined threshold. This predetermined threshold may be a first threshold.

In the present example, the first valve 112a arranged at the outlet of the first water storage tank 102. The first valve 112a may thus control the flow from the first water storage tank 102 to the third user unit 110. The second valve 112b is arranged at the outlet of the second water storage tank 106. The second valve 112b may thus control an outflow from the second water storage tank 106. The third valve 112c may control an inflow to the first water storage tank 102 from the second water storage tank 106. The placement of the valves of the valve arrangement 112 in the present illustrative example is to be seen as a non-limiting example. As the skilled person would readily understand, other arrangements of valves may be possible as well. For example, the system may be without the second or third valve 112b, 112c, since one of them may be sufficient to control the water flow between the second water storage tank 106 and the first water storage tank 102.

The system may further comprise a number of water paths, e.g. water pipes, for transferring the used water within the system. In the present example, a number of water paths are illustrated by lines connecting the different parts of the system. To further improve the understanding, arrows indicating the flow of direction within the water paths are also shown. Cross sections where two water paths meet are indicated by small circles, which will become apparent in Fig. 2. However, it should be noted that additional water paths may be present as is readily understood by the skilled person. Further, the length and placement of the water paths are to be seen as a non-limiting example to illustrate how the different elements of the system 100 may be connected.

The water distribution system 100 may preferably be installed in a bathroom. The first user unit 104 may be a sink. The first water storage tank 102 may then be arranged under the sink. Alternatively, the first user unit 104 may be a shower or a bathtub. The third user unit 110 may be a toilet. Thus, the first water storage tank may supply water to a cistern of the toilet. As is well known within the field of water recycling, a toilet need not to use fresh water. Thus, the water from the sink may be used to flush the toilet. However, as realized by the inventors of the present inventive concept, the amount of used water collected from a sink may not be enough to supply a toilet. Another water source which is becoming a more and more common sight in bathrooms are washing machines. Hence, the second user unit 108 may be a washing machine. Alternatively, the second user unit 108 may be a shower or a bathtub. The second user unit 108 may be a user unit which generates relatively more used water than the first user unit 104.

The system 100 may further comprise a sensor arrangement 116. The sensor arrangement 116 may comprise one or more sensor units. A sensor unit may be configured to measure one or more properties associated with the used water. For example, the sensor unit may be configured to measure one or more of an electrical conductivity of the used water, a turbidity of the used water, a pH-value of the used water and a water level in the first and/or second water storage tank 102, 106.

In the illustrated example of Fig. 1 , the sensor arrangement 116 comprises a first sensor unit 116a. The first sensor unit 116a may be provided in or in connection to the first water storage tank 102. The first sensor unit 116a may be arranged to measure properties of the incoming used water from the first user unit 104. Hence, the first sensor unit 116a may be arranged at the inlet to the first water storage tank 102. Alternatively, or in combination, the first sensor unit 116a may be arranged to measure properties of the used water stored in the first water storage tank 102. Hence, the first sensor unit 116a may be arranged in the first water storage tank 102 or at a wall of the first water storage tank 102.

The system 100 may further comprise a control unit (not shown) configured to perform the overall control of the system 100. For example, the control unit may be communicatively connected to the valve arrangement 112 and the sensor arrangement 116 for transmitting and receiving data and/or instructions therebetween. The control unit may be part of the valve arrangement 112.

The system may further comprise a discharging outlet. The discharging outlet may be arranged to drain used water from the system which is not to be used in the third user unit 110. In the example illustrated herein, the system 100 comprises a first discharging outlet 114a fluidly connected to the first water storage tank 102. The first discharging outlet 114a may be an overflow drain. In the example of Fig. 1 , the second water storage tank 106 does not comprise a discharging outlet. In case the second water storage tank 106 would overfill, the used water may be supplied to the first water storage tank 102 and, if necessary, be discharged through the first discharging outlet 114a.

Water may be discharged from the first water storage tank 102, by the valve arrangement 112, through the first discharging outlet 114a if a measured water quality parameter of the used water in the first water storage tank 102 is below a quality threshold. Thus, water which are not suitable for re-utilization may be discharged. The sensor arrangement 116 may be arranged to measure the quality of the water before it enters the first water storage tank 102. In that case, water may be discharged before it enters the first water storage tank 102 (depending on the measured quality) such that it does not lower the quality of water already present in the first water storage tank 102.

Water may be discharged from the first water storage tank 102, by the valve arrangement 112, through the first discharging outlet 114a if a measured first water level in the first water storage tank 102 is above a first overflow threshold. Hence, overflow of the first water storage tank 102 may be avoided. The first overflow threshold may be a maximum storage capacity of the first water storage tank 102.

The first water storage tank 102 may have a first storage capacity. The second water storage tank 106 may have a second storage capacity. The second storage capacity may be larger than the first storage capacity. For example, the second storage capacity may be 2 to 4 times larger than the first storage capacity. In other words, the second water storage tank 106 may be configured as a buffer tank to the first water storage tank 102, for example in the sense that the second water storage tank 106 may store a larger amount of water which can be transferred to the first water storage tank 102 if needed.

The system 100 may further comprise a pump 118. The pump 118 may be arranged to pressurize the used water in the system 100. In other words, the pump 118 may be arranged in the system 100 such that it enables water to be drawn from the first water storage tank 102 to the third user unit 110. The pump 118 may be further arranged in the system such that it enables water to be drawn from the second water storage tank 106 to the first water storage tank 102. The pump 118 may be arranged at any suitable position in the system 100. For example, the pump 118 may be arranged downstream to the first and/or second water storage tank 102, 106. In the example of Fig. 1 , the pump 118 is provided at the water path between the second water storage tank 106 and the first water storage tank 102 such that used water may be drawn from the second water storage tank 106 to the first water storage tank 102.

Even though only one pump 118 is illustrated herein, the system 100 may comprise additional pumps. For example, an additional pump may be arranged at the outlet of the first water storage tank 102 to draw used water from the first water storage tank 102 to the third user unit 110. The placement and number of pumps in the illustrated example should be seen as a nonlimiting example. As the skilled person readily understands, pumps may be provided at any suitable position in the system 100.

The pump 118 may be controlled by the control unit. The system 100 may further comprise a water treatment unit (not shown). The water treatment unit may be configured to treat the used water stored in the first water storage tank 102 with regard to at least one water quality parameter. The water treatment unit may be configured to treat the used water stored in the second water storage tank 106 with regard to at least one water quality parameter. The water treatment unit may thus improve the quality of the used water, for instance by removing certain contents, in order to reduce an amount of water which otherwise may have to be discharged.

The system 100 may comprise one or more filters for purifying the used water. Filters may for instance be provided at the inlet of the first water storage tank 102 and/or the inlet of the second water storage tank 106. The one or more filters may be carbon filters.

Figure 2 illustrates, by way of a second example, the water distribution system 100 for enabling recycling of water. The system 100 as illustrated in Fig. 2 shares many features with the system 100 as illustrated in the example of Fig 1. In order to avoid undue repetition, reference is made to the above.

In addition to what is mentioned in connection with Fig. 1 , the system 100 as illustrated by the example of Fig. 2 further comprises a water path fluidly connecting the second water storage tank 106 with the third user unit 110. In other words, the outlet of the second water storage tank 106 may be fluidly connected to the third user unit 110. The valve arrangement 112 may be further arranged such that the second water storage tank 106 may supply the third user unit 110 with water directly, without going through the first water storage tank 102. This may be achieved by a fourth valve 112d of the valve arrangement 112 as illustrated herein. The third and fourth valve 112c, 112d may thus be used to direct the used water from the second water storage tank 106 either to the first water storage tank 102 or directly to the third user unit 110.

More specifically, the valve arrangement 112 may be arranged such that water may be supplied to the third user unit 110 from the first water storage tank 102 if the water level of the first water storage tank 102 is above a predetermined threshold. This predetermined threshold may be a second threshold. The predetermined threshold may be a minimum water level that is allowed for the first water storage tank 102 to have if water is to be supplied from the first water storage tank 102 to the third user unit 110. The predetermined threshold may ensure that the first water storage tank 102 is not completely emptied after supplying water to the third user unit 110. If the water level of the first water storage tank 102 is below the predetermined threshold (or in other words the second threshold), water may be supplied to the third user unit 110 from the second water storage tank 106.

The second threshold may be a different threshold than the first threshold mentioned above in connection with Fig. 1. However, the second threshold may be the same threshold as the first threshold. In case the first and second threshold are the same threshold, water from the second water storage tank 106 may either be supplied to the first water storage tank 102 or to the third user unit 110.

The pump 118 may be provided just upstream of the third user unit 110. For example, the pump 118 may be provided where the fourth valve 112d is provided.

The sensor arrangement 116 may comprise a second sensor unit 116b arranged in or in connection with the second water storage tank 106, as illustrated herein. The second sensor unit 116b may measure the same properties as the first sensor unit 116a. The second sensor unit 116b may be arranged at the inlet of the second water storage tank 106. The second sensor unit 116b may be arranged in the second water storage tank 106 or at a wall of the second water storage tank 106.

The second sensor unit 116b may provide information to the water treatment unit relating to the quality of the used water stored in the second water storage tank 106.

The present example of the system 100 further comprises a second discharging outlet 114b. The first and second discharging outlets 114a, 114b may be separate from each other as illustrated herein. Alternatively, the first and second discharging outlets 114a, 114b may be connected to a common drain. Water may be discharged from the second water storage tank 106, by the valve arrangement 112, through the second discharging outlet 114b if a measured water quality parameter of the used water in the second water storage tank 106 is below the quality threshold. As with the first water storage tank 102, used water may be discharged before entering the second water storage tank 106 if the sensor arrangement 116, or more specifically the second sensor unit 116b, determines that the water quality is below the quality threshold.

Water may be discharged from the second water storage tank 106, by the valve arrangement 112, through the second discharging outlet 114b if a measured second water level in the second water storage tank 106 is above a second overflow threshold.

If one of the water storage tanks, for example the first water storage tank 102 may be about to overflow, used water stored in the first water storage tank 102 may be supplied to the other water storage tank, i.e. the second water storage tank 106 in this example, instead of being discharged. In this way, more water can be recycled instead of having to be discharged.

Having the first and second water storage tanks 102, 106 as separate tanks which both has a fluid connection to the third user unit separate from each other allows the water treatment unit to treat water in one of the water storage tanks while the third user unit is supplied with used water from the other water storage tank not currently being treated. For example, if the at least one water quality parameter of the first water storage tank 102 is lower than the at least one water quality parameter of the second water storage tank 106, the used water in the first water storage tank 102 may be treated by the water treatment unit while the third user unit 110 may be supplied with used water from the second water storage tank 106, and vice versa.

The inlet of the first water storage tank 102 may be fluidly connected to an external water supply 120 as illustrated herein. For example, the first water storage tank 102 may be connected to a cold fresh water source which the first user unit 104 is connected to. The valve arrangement 112 may be arranged such that water from the external water supply 120 may be supplied to the first water storage tank 102 if the water level of the first water storage tank 102 is below the predetermined threshold and a water level of the second water storage tank 106 is below another predetermined threshold. In other words, if there is not enough water either in the first water storage tank 102 or in the second water storage tank 106, water may be supplied from the external water supply 120. Here, the predetermined threshold may be a third threshold. The another predetermined threshold may be a fourth threshold. The third threshold may be a different threshold than the first and/or second threshold as mentioned above. However, the third threshold may be the same threshold as the first and/or second threshold. Similarly, the fourth threshold may be a different threshold than the first, second and third threshold. However, the fourth threshold may be the same threshold as the first, second and/or third threshold. The valve arrangement 112 may comprise a fifth valve 112e arranged at the water path between the external water supply 120 and the inlet of the first water storage tank 102 to control the flow from the external water path 120.

Figure 3a-c are flow charts illustrating the steps of the method 300 for recycling of water in a water distribution system. The water distribution system may comprise: a first water storage tank, wherein an inlet of the first water storage tank may be fluidly connected to a drain of a first user unit; a second water storage tank, wherein an inlet of the second storage tank may be fluidly connected to a drain of a second user unit; and a valve arrangement arranged to control the flow of the used water within the system; wherein an outlet of the first water storage tank may be fluidly connected to a third user unit; and wherein an outlet of the second water storage tank may be fluidly connected to the first water storage tank. The water distribution system may be the water distribution system described above in connection with Fig. 1 and 2.

Below, the different steps are described in more detail. Even though illustrated in a specific order, the steps of the method 300 may be performed in any suitable order, in parallel, as well as multiple times.

Used water from the first user unit is collected S302 in the first water storage tank. Used water from the second user unit is collected S304 in the second water storage tank.

Used water from the first water storage tank is supplied S306, by use of the valve arrangement, to the third user unit for recycling.

Used water from the second water storage tank is supplied S308, by use of the valve arrangement, to the first water tank.

Supplying S308 used water from the second water storage tank to the first water storage tank may be performed in response to a water level of the first water storage tank being below a predetermined threshold.

The water distribution system may further comprise a water discharging outlet and a sensor arrangement.

At least one water quality measure of the used water in the first water storage tank and/or in the second water storage tank may be determined S310, by the sensor arrangement.

In response to the at least one measured water quality parameter in the first and/or second water storage tank being below a quality threshold, water from the first water storage tank and/or the second water storage tank respectively may be discharged S312, by use of the valve arrangement, through the water discharging outlet. In other words, if the water quality of the used water in the first water storage tank is below the quality threshold, the used water of the first water storage tank may be discharged. Similarly, if the water quality of the used water in the second water storage tank is below the quality threshold, the used water of the second water storage tank may be discharged.

The outlet of the second water storage tank may be fluidly connected to the third user unit.

Supplying S306 used water from the first water storage tank to the third user unit may be performed in response to the water level of the first water storage tank being above a predetermined threshold. In response to the water level of the first water storage tank being below the predetermined threshold, water from the second water storage tank may be supplied S316, by use of the valve arrangement, to the third user unit. The inlet of the first water storage tank may be fluidly connected to an external water supply. In response to the water level of the first water storage tank being below the predetermined threshold and a water level of the second water storage tank being below another predetermined threshold, water from the external water supply may be supplied S314, by use of the valve arrangement, to the first storage tank.

Additionally, variations to the disclosed variants can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.