Procedure for flushing a pipe network in a building

Abstract

A rinsing method (100) for a non-food-use piping system in a building (50), the method (100) being characterized in that it comprises the following steps: a) injection (110) of water through an inlet point of the system to perform a first rinse, b) recovery (120) of the water after the first rinse through an outlet point of the system, c) filtration (130) of the recovered water by passing it - through (132) a first filter called a mechanical filter (6), then - through (134) a second filter called a clarifier (8), d) reinjection (140) of the filtered water into the inlet point of the system to perform a second rinse. Figure 2

Description

Title of the invention: Method for flushing a pipe network in a building

[0001] The invention relates to a method for flushing a non-food-use piping system in a building, in particular an HVAC (Heating, Ventilation and Air Conditioning) system. The invention also relates to a flushing installation for carrying out the flushing process.

[0002] HVAC (Heating, Ventilation, and Air Conditioning) systems maintain thermal comfort and optimal indoor conditions in buildings, whether residential, office, factory, or other types of structures. An HVAC piping network refers to the physical installation that enables the HVAC system to operate throughout the building. Such an HVAC network includes all types of piping that distributes air, heat, and / or cold to different areas of the building.

[0003] Following system installation or maintenance, the pipes must be flushed to remove dust, debris, or other undesirable materials and ensure the proper functioning of the HVAC system. Generally, after installation or maintenance of such a network, the pipes are flushed by continuously introducing water into them from an inlet to an outlet, for a certain period of time until clear water is obtained, indicating that the debris and dust have been removed. This flushing step uses potable water from a local distribution network and requires a large quantity of water, for example, approximately 4500 L (liters) for a given network. Furthermore, at the outlet of the pipe network, the wastewater often contains impurities, such as scale, welding, and toxic metal filings, which can be discharged into the sewer system.Regulations, notably the Paris sanitation regulations, mandate the treatment of such wastewater before it is discharged into the sewers. However, these standards are not always respected, particularly due to the number of rather time-consuming steps involved.

[0004] The invention aims in particular to provide a more environmentally friendly rinsing process, while guaranteeing its effectiveness, for a non-food use piping network in a building.

[0005] To this end, the invention relates to a method for rinsing a non-food-use piping network in a building, the method being characterized in that it comprises the following steps: a) injection of water through a network entry point to perform an initial flush, b) recovery of water after the first rinse via a network outlet point, c) filtration of the recovered water by passing - through a first filter called a mechanical filter, then - through a second filter called a clarifier, d) reinjection of the filtered water into the network entry point to perform a second rinse.

[0006] The invention thus proposes to reuse water already used for a first rinse to perform a second rinse. To this end, the water exiting the first rinse is filtered before being reused for the second rinse. Thanks to this reuse, the amount of water consumed during the rinsing of the pipe network, particularly at the end of a construction project, is greatly reduced, and the process is therefore much more environmentally friendly. Indeed, unlike the prior art, the rinsing process proposed here does not require circulating potable water continuously through the network for a certain period until a "clean" pipe network is obtained, that is to say, one free of impurities such as scale, welding, filings, sludge, or other types of undesirable matter.The process proposed here is particularly advantageous because it can, for example, reduce water consumption for rinsing pipes by approximately 85%, using only 700L instead of 4500L (litres) for rinsing one floor.

[0007] It is understood that the filtration steps make it possible to remove the particles from the first rinse to make the water recovered from the first rinse usable again, which avoids having to circulate additional potable water to carry out the rinsing.

[0008] A "mechanical filter" is defined as a filter configured to filter solid particles, generally considered to be large particles. For example, the mechanical filter includes a magnetic capture filter, which filters metallic debris. This magnetic capture filter may optionally be combined with an element for filtering sludge, for example, a fabric sock. Other types of mechanical filters could be used alternatively or in combination, for example, a pellet filter such as a "Birm" filter for removing metallic sediments.

[0009] A "clarifying filter" is defined as a filter configured to make water "clearer." It is understood that "water clarity" corresponds to a measure of the water's transparency, that is, its ability to transmit light. Water clarity can be influenced by the quantity and type of suspended particles. Preferably, the clarifying filter is a carbon filter, also called an activated carbon filter. Activated carbon has a surface area that gives it a high adsorption capacity. It It is thus able to retain organic compounds and other micropollutants in order to purify the water and improve its color.

[0010] It is therefore understood that the process proposes to rinse the same network repeatedly with an identical or close quantity of water, in a substantially closed circuit, until a satisfactory level of cleanliness is obtained.

[0011] The term "non-food piping network" means a set of pipes (or conduits) connected to transport a fluid that is not intended for food use, and therefore does not have to meet specific requirements such as those required for food use.

[0012] Preferably, the non-food piping network is a so-called "HVAC" network for "Heating, Ventilation and Air Conditioning", installed for the distribution of air, heat and / or cold in a building.

[0013] The method further comprises one or more of the following optional features, taken alone or in combination.

[0014] - The process is repeated so as to perform more than two rinses, step c) of filtration being preceded by a step of checking the clarity of the recovered water in step b) and, if the water is considered to be "not clear", it is filtered according to step c) and then reinjected according to step d) into the point of entry of the network to carry out another rinse.

[0015] This step allows the "cleanliness" of the network to be verified after each pass of water through it for rinsing. Indeed, the network often requires several rinses before all undesirable materials are removed. For example, after the second rinse, if the recovered water is considered "unclear," then it is concluded that the pipe is not sufficiently clean. In this case, the recovered water is sent to step c) for filtration and to step d) for a third rinse. It is understood that this verification step thus makes it possible to determine whether the network is clean enough to stop the rinsing steps, thereby avoiding the unnecessary execution of the other steps of the process. Preferably, the process comprises more than three rinsing cycles, and even more preferably more than five.It is understood that the more the process is used for a large number of rinsing cycles, the more water is saved compared to the conventional method using water from the continuous distribution network.

[0016] - The water clarity verification step is carried out by a visual test, by For example, a transparent pipe. This allows a technician or worker to visually verify if the water leaving the network is sufficiently clear by checking for suspended particles. The term "transparent pipe" includes a partially transparent pipe.

[0017] - Step c) of water filtration further includes a sedimentation step by means of a sedimentation tank, before the water passes through the clarifying filter.

[0018] Sedimentation, or decantation, ensures that the water flowing to the clarifying filter is free of solid particles. It can take place before or after passing through the mechanical filter.

[0019] - Water is introduced into the sedimentation tank by passing it through a pipe vertical, forcing it to first pass through the bottom of the sedimentation tank.

[0020] The vertical pipe thus forces the solid debris in the water to first pass through the bottom of the sedimentation tank, and therefore settle there quickly to improve sedimentation efficiency. Preferably, the vertical pipe is connected to an inlet port located high up in the sedimentation tank, so as to facilitate gravity flow. The pipe therefore keeps the solid matter at the bottom of the sedimentation tank, so that the water in the upper part of the tank can have a relatively laminar flow, less likely to disperse particles, before being directed to the clarifying filter.

[0021] - The sedimentation step takes place in two sub-steps using two tanks sedimentation tanks connected in series, the water having undergone sedimentation in a first sedimentation tank passing to a second sedimentation tank by overflow.

[0022] Thus, in the event of remaining solid matter, the second sedimentation tank allows for further sedimentation of the remaining solid matter in the water.

[0023] - After the second rinse or a subsequent rinse, the recovered water is stored then used in another non-food-use piping network.

[0024] Thus, not only does the proposed process reduce the water used for rinsing the same network, but the same water can also be advantageously used to rinse a network in another building.

[0025] Alternatively, the water from the rinses is discharged into the sewer system at the end of the construction project. This alternative is particularly advantageous because the water from the rinses has already been treated by passing through the mechanical filter and the clarifying filter and therefore no longer contains undesirable particles. Consequently, this water meets sanitation standards and can be discharged into the sewer system. In other words, this recovered water does not require any additional treatment steps.

[0026] - The passage of the water flow through the filters is facilitated by the use of at least a booster pump.

[0027] Preferably, the booster pump is configured to increase the pressure to ensure the movement of water in the rinsing system. Preferably, the The booster pump is configured to maintain a constant flow of water in the rinsing system, thus the booster pump makes rinsing faster.

[0028] - The process includes a step of cleaning the mechanical filter according to a The cleaning frequency should be between hourly and daily (24 hours), preferably between every 3 and every 5 hours. This cleaning frequency ensures effective rinsing.

[0029] The invention also relates to a rinsing installation for implementing a rinsing process described above, the installation comprising: - a water inlet configured to be connectable to the network outlet point, - a mechanical filter located downstream of the water inlet, - a clarifying filter located downstream of the mechanical filter, - a water outlet configured to be connectable to the network entry point.

[0030] It is understood that this installation is particularly suitable to allow the implementation of the process and to provide all the advantages relating thereto.

[0031] The installation further includes one or more of the following optional features, taken alone or in combination.

[0032] - The installation is mounted on a movable platform, for example a trolley on wheels. The movable platform allows for the easy transport of the various elements of the installation from one site to another, without requiring dismantling and reassembling these different elements.

[0033] - The installation includes a booster pump for starting and circulating water in the system. Preferably, the booster pump is located between the mechanical filter and the clarifying filter. Ideally, the system includes an additional booster pump located upstream of the network inlet point.

[0034] - The installation includes an observation module located downstream of the point of outlet from the network, allowing for verification of water clarity. For example, the observation module includes a transparent conduit allowing for the determination of water clarity through a visual test.

[0035] - The installation includes a sedimentation tank located downstream of the filter mechanical. Optionally, the installation includes two sedimentation tanks connected in series.

[0036] - A vertical rod is connected to an inlet port arranged high in the sedimentation tank, to direct the water first towards the bottom of said tank upon entering the sedimentation tank.

[0037] - The installation includes a compressed air injector arranged upstream of the outlet of water from the installation. Preferably, the installation also includes a deaerator located downstream of the network outlet point, to eliminate disturbances in the flow of water to be filtered.

[0038] The compressed air injector creates disturbances, particularly bubbles, which can collide with the inner walls of the pipes to be flushed, causing the detachment of any materials that may be stuck to these inner walls. Thus, the compressed air injector contributes to the effective flushing of the system. The deaerator eliminates disturbances or bubbles that could damage the various filters, or it removes gas bubbles, which are then reintroduced into the pipes for subsequent flushing.

[0039] - A recovery tank is connected downstream of the network outlet point to recover the water after it has passed through the network and before it passes through the rinsing installation.

[0040] - The installation is configured to receive a water volume of between 500 L (litres) and 1000L of water, preferably close to 700L. Brief description of the figures

[0041] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which:

[0042] [Fig. 1] is a schematic view of a first embodiment of a rinsing installation according to the invention

[0043] [Fig.2] is a diagram illustrating a rinsing process using the installation of the [Fig.l].

[0044] [Fig.3] is a schematic view of a second embodiment of an installation rinsing according to the invention.

[0045] [Fig.4] is a perspective view of the installation of [Fig.3].

[0046] [Fig.5] is a perspective view of a movable platform capable of carrying to less a part of the installation of [Fig.4].

[0047] [Fig.6] is a schematic view of a third embodiment of an installation rinsing according to the invention. Detailed description

[0048] Figures 1, 3, and 6 show three different embodiments of a flushing installation 1. Each installation 1 is intended to be connected to a building 50 (shown schematically and only in [Fig. 1]), more specifically to a non-food-use piping network of the building 50. In the following description, the non-food-use piping network corresponds to an HVAC (Heating, Ventilation, and Air Conditioning) type network installed for the distribution of air, heat, and / or cold in the building 50. The flushing installation 1 allows the building 50 piping network to be flushed with water at the end of the construction project, particularly after the network has been installed or maintained.

[0049] In the first embodiment shown in [Fig. 1], the rinsing system 1 comprises a water inlet 2, connected to an outlet 52 of the network, and a water outlet 4, connected to an inlet 54 of the network. In this example, the system 1 includes a mechanical filter 6 located downstream of the water inlet 2 of the system 1, and a clarifying filter 8 located downstream of the mechanical filter 6. The mechanical filter 6 and the clarifying filter 8 are connected in series, meaning that the water must pass through one and then the other. According to this first embodiment, the mechanical filter 6 corresponds to a magnetic capture filter 6, which filters out metallic debris. The clarifier filter 8 is preferably a carbon filter, also called an activated carbon filter, capable of retaining organic compounds and other micropollutants in order to purify the water and improve its color.The rinsing installation 1 further includes a sedimentation tank 10 located upstream of the clarifying filter 8. In particular, the sedimentation tank 10 is equipped with a vertical pipe 12 connected to an inlet port 14 of the sedimentation tank 10, this inlet port 14 being located high on the sedimentation tank 10 and communicating with the magnetic capture filter 6. In addition, it should be noted that the sedimentation tank 10 has two floats 16, respectively high and low, which indicate the water level in the sedimentation tank 10. Furthermore, the installation 1 includes a booster pump 18 located between the mechanical filter 6 and the clarifying filter 8, more specifically between the sedimentation tank 10 and the clarifying filter 8.Installation 1 is mounted on a platform 20; this platform 20 is advantageously movable to allow the transport of the various elements of installation 1 from one site to another, by means of a trolley similar to that shown in [Fig.4].

[0050] Figure 2 represents a process 100 for flushing the piping network using the flushing installation 1 of Figure 1. The process 100 involves injecting water 110 through the network inlet 54 to perform a first flush. The water then passes into the building network 50, and the process 100 includes a step 120 for recovering the water after the first flush, through the network outlet 52. This recovered water then undergoes a filtration step 130, which comprises the following steps: - passage 132 in the magnetic capture filter 7, then - sedimentation 134 using sedimentation tank 10, then - passage 136 through the clarifying filter 8. In particular, the water to be settled is received in the sedimentation tank 10 by the pipe 12, which forces the water from the magnetic capture filter 6 to pass through the bottom of the sedimentation tank 10. The vertical pipe 12 thus forces the solid debris contained in the water from the magnetic capture filter 8 to pass through all first, the particles settle to the bottom of the sedimentation tank 10. Thus, the sedimentation step 134 ensures that the water flowing towards the clarifying filter 8 is free of large solid particles. According to an unshown variant of this first embodiment, the sedimentation step 134 can take place before the water passes 132 through the magnetic capture filter 6.

[0051] After the filtration steps 130, the filtered water is reinjected during a step 140 into the network's inlet point 54 to perform a further rinse. It is therefore understood that the water leaving the network passes through the installation 1 before being reinjected 140 into the same network, forming a closed circuit, or a substantially closed circuit if some water is reintroduced during the rinses to compensate for evaporation or to replenish the water volume. Thus, process 100 allows the reuse of water already used for a first rinse to perform a second rinse. Thanks to this reuse, the amount of water consumed during the rinsing of the pipe network, particularly at the end of a project, is greatly reduced, and process 100 is therefore much more environmentally friendly.

[0052] During the implementation of process 100, the passage of the water flow through the filters 6, 8 is facilitated by the activation of the booster 18. This booster 18 is configured to increase the pressure in order to ensure the movement of the water in the installation 1. Preferably, the booster 18 is also configured to maintain a constant flow in the installation 1, thus the booster 18 makes the rinsings faster.

[0053] The network may require several rinses before being sufficiently clean. Therefore, the water exiting the installation 1 is reinjected 140 and the rinsing process 100 is repeated until the network is considered clean. The filtration step 130 is thus advantageously preceded by a verification step 150 of the clarity of the water recovered from the network. At the end of this step 150, if the water is considered "not clear," it is followed by the filtration step 130 and then reinjected 140 into the network to perform another rinse. Conversely, if at the end of the verification step 150 the water is considered "clear," the process is followed by a shutdown step 160 of the installation. This verification step 150 is advantageously carried out by a visual inspection. For this purpose, the water inlet 2 of the network includes a transparent conduit.A technician or worker can visually verify that the water leaving the network is sufficiently clear by checking for suspended particles. After the various rinsing cycles, when process 100 is shut down 160, the recovered water is stored in the installation and then used in another pipeline network. Alternatively, the recovered water can also be discharged into the sewer system at the end of the project, without requiring any additional treatment steps.

[0054] With reference to [Fig. 3], the installation 1 according to a second embodiment is shown. This second embodiment includes elements similar to those of the first embodiment, in particular the mechanical filter 6, the clarifying filter 8 located downstream of the mechanical filter 6, and a booster pump 18 located upstream of the clarifying filter 8. Unlike the first embodiment, in this second embodiment, the installation 1 includes a recovery tank 22 which is connected downstream of the outlet 52 of the network to recover the water after it has passed through the network. The recovery tank 22 is located upstream of the sedimentation tank 10 and communicates with the vertical pipe 12 of the sedimentation tank 10. It is understood, however, that this tank 22 is optional.Furthermore, it is noted that installation 1 comprises two sedimentation tanks connected in series: the first sedimentation tank 10 connected to the recovery tank 22, and a second sedimentation tank 10' located between the first sedimentation tank 10 and the clarifying filter 8. An additional booster pump 18' is also provided upstream of the water outlet 4 of installation 1. A storage module 24 is located downstream of the clarifying filter 8; this storage module 24 allows for the storage of water awaiting reinjection into the network. It is understood that the sedimentation tank 10, the sedimentation tank 10', and the storage module 24 correspond to tanks that can advantageously each hold between 150 and 700 L of water, preferably from 200 to 500 L. Moreover, it is noted that installation 1 is supported by two separate platforms 20 and 20'.A first platform 20 carries the mechanical filter 6, the two sedimentation tanks 10, 10' and one of the blowers 18. A second platform 20' carries the clarifying filter 8, the storage module 24 and the additional blower 18'. Each platform 20, 20' can advantageously be mounted on wheels.

[0055] The rinsing process implemented in this second embodiment is substantially similar to process 100 described above, except for the filtration step 130. In fact, the water recovered from the network outlet is filtered first by passing through the first sedimentation tank 10 and then through the mechanical filter 6 via step 132. The water from the mechanical filter 6 is then returned to the first sedimentation tank 10. The water that has undergone sedimentation in the first sedimentation tank 10 overflows into the second sedimentation tank 10'. Thus, the sedimentation step 134 takes place in two sub-steps using these two sedimentation tanks 10, 10' connected in series. Thanks to its passage 134 through two tanks, in the event of solid particles remaining in the water, the second tank 10' allows for further and finer sedimentation.Next, the booster pump 18 pumps the settled water to the clarifying filter 8 according to step 136. then to storage module 24, and the additional booster 18' pumps the filtered water to the network entry point 54 to perform a further rinse.

[0056] Figure 4 is a perspective view of the installation of Figure 3. It shows the first platform 20, which carries the mechanical filter 6, the two sedimentation tanks 10 and 10', and the blower 18, and the second platform 20', which carries the clarifying filter 8, the storage module 24, and the blower 18'. Figure 5 shows an example of a trolley capable of carrying, for example, the first platform 20. More precisely, this first platform 20 is in the form of a trolley with wheels 26, preferably swivel wheels, allowing the installation 1 to be moved from one worksite to another. The trolley has horizontal and vertical supports arranged to define two compartments 28 and 28', adapted to hold the two sedimentation tanks 10 and 10', respectively.

[0057] Figure 6 represents a third embodiment according to the invention. As in the second embodiment, two platforms 20, 20' are provided. The first platform 20 carries the mechanical filter 6, the sedimentation tank 10, the clarifying filter 8, and a blower 18 with a pump 19. The second platform 20' carries at least the storage module 24.

[0058] This third embodiment is similar to the first and second embodiments in that it includes the mechanical filter 6, the sedimentation tank 10, the clarifying filter 8, a first booster 18 located downstream of the clarifying filter 8, the storage module 24 and an additional booster 18' located downstream of the storage module 18. In the example of this third embodiment, the additional booster 18' is a three-phase type booster. Unlike the other two embodiments, in this third embodiment, the installation 1 also includes at least one compressed air injector 30 arranged upstream of the water outlet 4 of the installation 1. More specifically, a first compressed air injector 30 is arranged between the clarifier filter 8 and the storage module 24, and a second compressed air injector 30' is arranged downstream of the storage module 24.Installation 1 also includes a degasser 32 located downstream of the network outlet 52. Each compressed air injector 30, 30' creates disturbances, particularly bubbles, which can collide with the inner wall of the network pipes, causing the dislodging of any materials that may be adhering to the inner wall of the network pipe. Thus, the compressed air injector 30, 30' contributes to the effective flushing of the network. The degasser 32 eliminates disturbances or bubbles that could damage the various filters during their operation.

[0059] The rinsing process using this third embodiment is substantially similar to process 100 implemented in the first embodiment, except that here, at the inlet 2 of the installation, the recovered water from the network is degassed to remove any bubbles that may be present in this recovered water, due to the compressed air supplied. Then, after the filtration step 130 and before the reinjection 140 of the water into the network inlet point, the compressed air injector 30, 30' is activated to generate bubbles, thus improving the network rinsing efficiency.

[0060] The invention is not limited to the embodiments shown and other embodiments will be obvious to a person skilled in the art. List of references

[0061] 1: rinsing installation 2: Water inlet of installation 1 4: Water outlet from installation 1 6: Mechanical filter 8: Clarifying filter 10, 10': Sedimentation tank 12: Vertical pipe 14: Inlet port of the sedimentation tank 16: float 18, 18': booster pump 19: pump 20, 20': platform 22: Recycling bin 24: storage module 26: casters 28, 28': housing for receiving sedimentation tanks 10, 10' 30, 30': compressed air injector 32: Degasser 50: building 52: network exit point 54: Network entry point 100: Rinsing process 110: Water injection via a network inlet point to perform a first rinse. 120: Water recovery after the first rinse via a network outlet point. 130: Filtration of the recovered water. 132: Filtration by passing through a first filter, known as a mechanical filter 134: Sedimentation stage 136: Filtration by passing through a second filter called a clarifier 140: Reinjection of filtered water into the network inlet point to perform a second rinse 150: Verification step 160: Process 100 is shut down

Claims

Demands

1. A method for rinsing (100) a non-food-use piping network in a building (50), the method (100) being characterized in that it comprises the following steps: a) injection (110) of water through an inlet point of the network to carry out a first rinse, b) recovery (120) of the water after the first rinse through an outlet point of the network, c) filtration (130) of the recovered water by passing - through (132) a first filter called a mechanical filter (6), then - through (134) a second filter called a clarifier (8), d) reinjection (140) of the filtered water into the inlet point of the network to carry out a second rinse.

2. A method (100) according to the preceding claim, repeated so as to carry out more than two rinses, the filtration step (130) being preceded by a verification step (150) of the clarity of the water recovered in step b) and, if the water is considered to be "not clear", it is filtered according to step c) and then reinjected according to step d) into the point of entry (54) of the network to carry out another rinse.

3. A method according to the preceding claim, wherein the verification step (150) of the water clarity is carried out by a visual test, for example by a transparent conduit.

4. A method (100) according to any one of the preceding claims, wherein the water filtration step (130) further comprises a sedimentation step (136) by means of a sedimentation tank (10, 10'), before the water passes through the clarifying filter (8).

5. Method (100) according to the preceding claim, wherein water is introduced into the sedimentation tank (10, 10') by passing it through a vertical pipe (12) forcing the water to first pass through the bottom of the sedimentation tank (10, 10').

6. A method (100) according to any one of claims 4 or 5, wherein the sedimentation step (136) takes place in two substeps by means of two sedimentation tanks (10, 10') connected in series, the water having undergone sedimentation in a first sedimentation tank passing to a second sedimentation tank by overflow

7. A method (100) according to any one of the preceding claims, wherein, after the second rinse or a subsequent rinse, the recovered water is stored and then used in another non-food-use piping system.

8. Method (100) according to any one of the preceding claims, wherein the passage of the water flow through the filters is facilitated by the use of at least one booster (18, 18').

9. A method according to any one of the preceding claims, comprising a step of cleaning the mechanical filter at a frequency between every hour and every day, preferably between every 3 hours and every 5 hours.

10. Rinsing installation (1) for implementing a rinsing process according to any one of claims 1 to 9, the installation comprising: - a water inlet (2) configured to be connectable to the outlet point (52) of the network, - a mechanical filter (6) disposed downstream of the water inlet (2), - a clarifying filter (8) disposed downstream of the mechanical filter (6), - a water outlet (4) configured to be connectable to the inlet point (54) of the network.

11. Installation (1) according to the preceding claim, mounted on a movable platform (20, 20'), for example a trolley on wheels.

12. Installation (1) according to any one of claims 10 or 11, further comprising a sedimentation tank (10, 10') disposed downstream of the mechanical filter, optionally the installation comprises two sedimentation tanks (10, 10') connected in series.

13. Installation (1) according to any one of claims 10 to 12, further comprising a compressed air injector arranged upstream of the water outlet (4) of the installation, preferably the installation includes a degasser disposed downstream of the outlet point (54) of the network to eliminate disturbances in the flow of the water to be filtered.

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