Device and method for purifying drinking water

Abstract

In order to improve the lifespan of the semi-permeable membrane or the yield of the reverse osmosis system in the treatment of drinking water by means of reverse osmosis, the invention provides a device for treating drinking water with at least one reverse osmosis vessel which is divided into at least two chambers by at least one semi-permeable membrane, wherein a first chamber has an inlet for the water to be treated and an outlet for the concentrate, and the second chamber has an outlet for the treated water, wherein the device comprises at least one pressure vessel which is connected to the outlet for the treated water via a line, wherein the device is designed in such a way that, in an idle state, treated water flows out of the pressure vessel, through the semi-permeable membrane and into the first chamber.

Claims

1.-21. (canceled)

22. A method for purifying drinking water, comprising: conveying, during an extraction operation mode, drinking water to be purified through a semipermeable membrane (11) in reverse osmosis operation and separating the drinking water into permeate and concentrate; allowing, during an extraction stop, the permeate to flow into a pressure tank (4), whereby a supply of permeate accumulates and is pressurized in the pressure tank (4); and backflushing, during an idle operation state, permeate accumulated in the pressure tank through the membrane (11) due to an overpressure and thereby displacing the concentrate on a concentrate side of the membrane and removing deposits that may be present on the concentrate side of the membrane.

23. The method for purifying drinking water as claimed in claim 22, wherein a pressure difference across the semipermeable membrane (11) for conveying the permeate through the semipermeable membrane (11) is in a range between 0.05 bar and 1 bar.

24. The method for purifying drinking water as claimed in claim 22, wherein, on the concentrate side of the semipermeable membrane (11), the drinking water has a conductivity of less than 100 S/cm in the idle operation state after the backflushing.

25. The method for purifying drinking water as claimed in claim 22, wherein a concentration gradient across the semipermeable membrane (11) between the concentrate side and a permeate side is minimized in the idle state, after backflushing.

26. The method as claimed in claim 22, wherein the inlet water is disinfected only during extraction operation, but not in the idle state.

27. The method as claimed in claim 22, wherein only purified water is used for backflushing in the idle operation state.

28. A device (10) for purifying drinking water, comprising at least one reverse osmosis container (2; 100) which is divided by at least one semipermeable membrane (11) into a first chamber (21) and a second chamber (22), the first chamber (21) having an inlet for the water to be purified and an outlet for concentrate, and the second chamber (22) having an outlet for purified water; at least one pressure vessel (4) which is connected to the outlet for the purified water via a conduit (43); wherein the device (10) is configured such that in an idle operation state purified water flows back through the semipermeable membrane (11), from the pressure vessel (4) into the first chamber (21), wherein the pressure vessel (4) is configured such that, during an extraction stop, the permeate flows into a pressure tank (4), whereby a supply of permeate accumulates and is pressurized in the pressure vessel (4); and wherein, during an idle operation state, permeate accumulated in the pressure tank passes through the membrane (11) due to an overpressure and thereby displaces the concentrate on a concentrate side of the membrane and removes deposits that may be present on the concentrate side of the membrane.

29. The device (10) for purifying drinking water as claimed in claim 28, wherein the pressure vessel (4) has a holding capacity in a range between 0.1 liter and 5 liters.

30. The device (10) for purifying drinking water as claimed in claim 28, wherein the device (10) is designed for operation without electric power.

31. The device (10) for purifying drinking water as claimed in claim 28, wherein the pressure vessel (4; 40; 41) comprises an elastic material which is dimensioned and arranged so as to expand during an extraction operation state of the device (10), so that a restoring force is created in the elastic material, which during the idle operation state of the device (10) causes the material to relax, whereby purified water flows back from the pressure vessel (4; 40; 41) through the semipermeable membrane (11) into the first chamber (21).

32. The device (10) for purifying drinking water as claimed in claim 31, wherein the pressure vessel (4) comprises an elastic diaphragm.

33. The device (10) for purifying drinking water as claimed in claim 31, wherein the pressure vessel (4) is a flexible tube made of elastic material.

34. The device (10) for purifying drinking water as claimed in claim 28, wherein the device comprises a pressure vessel (4) in the form of a reservoir that is connected to a pressure boosting device.

35. The device (10) for purifying drinking water as claimed in claim 28, wherein the device (10) comprises a disinfectant feeding means which is connected to a conduit for the water to be purified, in particular to the inlet of the first chamber of the reverse osmosis container (2; 100) for the water to be purified.

36. The device (10) for purifying drinking water as claimed in claim 28, wherein the device (10) comprises an absorption means (9) for a disinfectant, which is connected to a permeate conduit (3).

37. The device (10) for purifying drinking water as claimed in claim 28, wherein the device (10) is not connected to a wastewater conduit on a permeate side.

38. The device (10) for purifying drinking water as claimed in claim 28, wherein the reverse osmosis container (100) is in the form of a filter candle.

39. A reverse osmosis system (1000) for drinking water, comprising: the device (10) as claimed in claim 28; a raw water conduit (1) for feeding water to be purified; an extraction conduit (3) for purified water; and a wastewater conduit (6; 7) for discharging concentrate.

40. The reverse osmosis system (1000) for drinking water as claimed in claim 39, wherein the reverse osmosis system (1000) comprises a shut-off valve (5) which couples the raw water conduit (1) and the extraction conduit (3) in such a way that when the valve (5) is opened, water to be purified is supplied to reverse osmosis and at the same time purified water is extracted.

41. The reverse osmosis system (1000) for drinking water as claim in claim 39, wherein the reverse osmosis system (1000 ) comprises a faucet valve (81) and a shut-off valve (5; 50, 51) which couples the raw water conduit (1) and the extraction conduit (3) in such a way that when the faucet valve (81) is closed the shut-off valve (5) is still open until the pressure tank (4) is filled and a predefined pressure differential is reached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The invention will now be explained in more detail by way of exemplary embodiments and with reference to the accompanying drawings in which the same and equivalent components are designated by the same reference numerals, while features of the different exemplary embodiments may be combined with one another, and wherein:

[0076] FIG. 1 is a schematic diagram of a device for purifying drinking water with a reverse osmosis container according to a first embodiment, which is installed below a kitchen worktop as part of an under-counter reverse osmosis system for drinking water.

[0077] FIG. 2 is a schematic diagram of a device for purifying drinking water according to a second embodiment .

[0078] FIG. 3 is a schematic diagram of a device for purifying drinking water according to a third embodiment .

[0079] FIG. 4 is a schematic diagram of a valve that can be employed in the device of FIGS. 1 to 3 for purifying drinking water.

[0080] FIG. 5 is a schematic diagram of a device for purifying drinking water according to a fourth embodiment .

[0081] FIG. 6 is a schematic diagram of a reverse osmosis container in the form of a filter candle for a device for purifying drinking water according to a third embodiment .

DETAILED DESCRIPTION

[0082] FIG. 1 shows an under-counter reverse osmosis system 1000 for domestic drinking water arranged below a kitchen worktop 8. The under-counter reverse osmosis system 1000 comprises a device 10 for purifying drinking water comprising a reverse osmosis container 2 and a pressure tank 4.

[0083] The under-counter reverse osmosis system 1000 furthermore comprises a raw water conduit 1 and a conduit 3 for purified water. Inlet water is supplied to the device 10 through the raw water conduit. During operation, purified water can be withdrawn from the device 10 through extraction conduit 3.

[0084] The under-counter reverse osmosis system may additionally have a further pressure accumulator. The latter may be arranged on the permeate side of the reverse osmosis container 2 and protected to this side by a backflow preventer. Such a further pressure tank will be subjected to the pressure that prevails in the conduit immediately upstream of this additional pressure tank and will be located upstream of the water faucet. FIG. 5 illustrates an embodiment of an under-counter reverse osmosis system 1000 in combination with such an additional pressure tank 400. When the water faucet is opened, the further pressure tank 400 ensures that permeate can always be withdrawn at a sufficient pressure via the water faucet.

[0085] The pressure tank 4, however, which is used for backflushing the semipermeable membrane of the reverse osmosis container 2 with permeate, is connected without a backflow preventer and applies pressures to the membrane during backflushing which are lower than the conduit pressure, in a range between about 0.05 bar and 1 bar.

[0086] In order to be able to provide a sufficient, preferably consistent pressure on the inlet side regardless of the installation situation, it is moreover possible to provide an electrically operated pump in the feed conduit, for example.

[0087] As furthermore illustrated in the diagram of FIG. 1, the reverse osmosis container 2 has a first chamber 21 and a second chamber 22. A semipermeable membrane 11 is arranged between chambers 21, 22.

[0088] When the device 10 and the under-counter reverse osmosis system 1000 are operated in the extraction mode, the input water supplied to the device 10 and thus to the reverse osmosis container 2, which has a conductivity of 500 S, for example, is conveyed through the semipermeable membrane 11. During this process, substances dissolved in the inlet water are retained in the first chamber 21, so that a concentrate is produced. The concentrate which has a conductivity of 1000 S, for example, can be discharged from the device 10 via concentrate conduit 6 and discarded via a wastewater conduit 7.

[0089] While the inlet water is conveyed through the semipermeable membrane 11, when the device 10 and the under-counter reverse osmosis system 1000 are operated in the extraction mode, the water entering the second chamber 22 will have a significantly reduced concentration of dissolved substances. This permeate is extracted as the purified water via a conduit 3.

[0090] When the valve 81 is closed, a pressure tank 4 connected to the permeate conduit 3 is filled with permeate via a conduit 43. After closing valve 81, the shut-off valve 5 remains open until the pressure tank 4 has been filled.

[0091] This is achieved purely hydraulically. The pressure tank 4 has a holding capacity in the range between approximately 0.1 l and 5 l, for example, and preferably the volume of the pressure tank is approximately 0.5 l to 1 l

[0092] The table below gives measured values from the operation of a device for purifying drinking water comprising a pressure tank with a holding capacity of 750 ml.

TABLE-US-00001 Volume Volume Conductivity until Volume feed Permeate peak is for back- Date [liters] Time Peak Feed flow/tank Concentrate depleted flushing Jan. 31, 2018 2077 2 min 13.8 S/cm 340 S/cm 5.9 S/cm 546 S/cm 200 ml 750 ml Feb. 1, 2018 2238 5 min 18 S/cm 340 S/cm 5.6 S/cm 559 S/cm 300 ml 750 ml Feb. 1, 2018 2285 10 min 16.4 S/cm 340 S/cm 5.6 S/cm 554 S/cm 400 ml 750 ml Feb. 1, 2018 2312 30 min 27.9 S/cm 340 S/cm 5.6 S/cm 554 S/cm 500 ml 750 ml Feb. 8, 2018 2979 60 min 59 S/cm 344 S/cm 6.7 S/cm 568 S/cm 650 ml 750 ml Feb. 8, 2018 2986 2 hours 84 S/cm 340 S/cm 6 S/cm 566 S/cm 650 ml 750 ml Feb. 12, 2018 3205 5 hours 85 S/cm 348 S/cm 6 S/cm 571 S/cm 650 ml 750 ml Feb. 13, 2018 3225 1 day 115 S/cm 348 S/cm 5.9 S/cm 571 S/cm 750 ml 750 ml Feb. 15, 2018 3123 2 days 98.8 S/cm 347 S/cm 5.8 S/cm 562 S/cm 750 ml 750 ml

[0093] For the measurements given in the table above, a pressure tank with 750 ml permeate was used for backflushing. Time refers to the downtime before extraction started. In the table the time is given in minutes unless otherwise noted. Peak refers to the high concentration in the extracted permeate at the beginning of extraction at the extraction point, that is the conductivity of the extracted permeate immediately at the beginning of the extraction mode. The required volume until peak is depleted is always less than or equal to the volume of the pressure tank of 750 ml. In order to reliably remain below a conductivity of 100 S/cm immediately at the beginning of the extraction (peak) even after about one day of stagnation, the volume of the pressure tank may be increased, for example to 1 liter.

[0094] It is also possible to use a reservoir (not shown) which is connected to a pump (not shown) as the pressure vessel. In this case, too, purified water will be conveyed into the reservoir in the extraction mode, in particular hydraulically.

[0095] In the absence of extraction, the device 10 and thus the under-counter reverse osmosis system 1000 is in an idle state which is also known as a standby state. With the loss of pressure applied to the water flowing into the chamber 21 and thus against the membrane 11 in the extraction state, with the entering into the idle state, a pressure will be built up to the membrane 11 from the side of the second chamber 22 by the permeate discharged out of the pressure tank 4 due to the pressure created in the pressure tank 4.

[0096] The emptying of the pressure tank 4 after entering the idle state and until the pressure differential as built up between the pressure tank 4 and the first chamber 21 during the extraction state has been equalized causes the automatic backflushing of the semipermeable membrane with the advantages and effects described above.

[0097] If a reservoir (not shown) connected to a pump (not shown) is used as the pressure vessel, the pump is connected so as to be enabled in response to the stop of extraction of the permeate and thus conveys purified water as accumulated in the reservoir into the second chamber 22 of the reverse osmosis container 2 and through the semipermeable membrane 11.

[0098] Since the backflushing from the second chamber 22 which holds the permeate after the extraction phase into the first chamber which holds the concentrate is an operation of the semipermeable membrane in the direction of osmosis instead of reverse osmosis, low pressure values are sufficient to enable backflushing, which pressure is provided by the pressure tank or the pump.

[0099] In particular if the device 10 is additionally equipped with a feeding or blending means for chlorine (not shown) for disinfection purposes in the case of contaminated raw water, it furthermore comprises an absorption device for removing the chlorine before the purified water is extracted. For this purpose, an activated carbon block 9 is provided in the illustrated exemplary embodiment.

[0100] The under-counter reverse osmosis system 1000 furthermore comprises a shut-off valve 5 which couples the raw water conduit 1 and the extraction conduit 3 in such a way that when the valve 5 is opened, water to be purified is supplied to reverse osmosis and at the same time purified water is extracted. The shut-off valve 5 may be coupled to the valve 81 of water faucet 80 or may replace it.

[0101] When the device 10 is in operation, the shut-off valve 5 has the effect that the device 10 for purifying drinking water is filled with raw water when the valve 81 of water faucet 80 is closed. Thus, when the valve 81 of faucet 80 is opened, water can immediately be withdrawn because water will already be available at the appropriate pressure.

[0102] FIGS. 2 and 3 illustrate further embodiments, and here the shut-off valve 5 is shown in two parts to illustrate the function thereof, although in the real implementation this constitutes a single component. This is illustrated in FIG. 4.

[0103] In the context of the present application, the shut-off valve is also referred to as a stop valve.

[0104] When water is extracted, the shut-off valve 5 opens the inlet for raw water to the concentrate side of the osmosis system. When the extraction of water has been stopped, e.g. once the faucet has been closed, the shut-off valve ensures that raw water continues to flow through the concentrate side until the permeate side has been re-pressurized, in particular until the pressure vessel has again been pressurized. It is only then that the shut-off valve closes the inflow of raw water to the concentrate side. For this purpose, the shut-off valve compares the pressure between the concentrate side and the permeate side and closes the raw water supply to the concentrate side when a design-dependent pressure differential is undershot.

[0105] For this purpose, the shut-off valve 5 may have two passages 50, 51 which are in contact via mutually corresponding diaphragms.

[0106] Shut-off valve 5 is in particular intended for use in a device for purifying drinking water which comprises a reverse osmosis container 2 and comprises a housing that defines an interior which has a water inlet connected to the feed conduit 1 and a water outlet connected to the concentrate conduit 6 and thus to the wastewater conduit 7. This fluid path represents the first passage 50 of shut-off valve 5. Furthermore, the interior of the valve 5 is connected to the permeate conduit 3 through its second passage 51.

[0107] The shut-off valve 5 may additionally have a piston, for example, that is coupled to a diaphragm plate and is configured to selectively open and close the first passage 50. In addition, at least one further diaphragm is coupled to the piston and the diaphragm plate. When the permeate pressure changes, the piston opens or closes the first passage 50 due to the deflection of the at least one diaphragm in response to the changes in permeate pressure in the second passage 51. The diaphragm plate, the piston, and the at least one further diaphragm thus form a hydraulic switching means which is designated by reference numeral 55 in the schematic diagram of FIG. 4.

[0108] The closing or opening of the first passage 50 or the second passage 51 of the shut-off valve occurs exclusively by virtue of the design of the two diaphragms in the passages of the shut-off valve.

[0109] When the consumer such as the valve 81 of water faucet 80 is closed, the first passage 50 of shut-off valve 5 will still remain open. While the pressure accumulator 4 is being filled, the pressure in the system increases until a particular pressure is reached. Thereby, the pressure differential between passages 50, 51 decreases. Once a design-dependent minimum pressure differential is reached, the valve 5 is closed by the diaphragm so that no further water will flow through the concentrate side, i.e. the first chamber of reverse osmosis 2.

[0110] According to the invention, only pure permeate is used for backflushing the membrane. No other fluid is introduced into the permeate conduit 3, in particular no gas such as compressed air or the like, for pressing the permeate counter to the extraction state flow direction from the second chamber 22 through the membrane 11 into the first chamber 21. The invention thus provides for a particularly simple and hygienic configuration of the device 10 for purifying drinking water.

[0111] FIGS. 2 and 3 illustrate further embodiments in which the function of the pressure tank is accomplished by a container made of elastic material, which is filled with purified water during the extraction state and thereby expands so that a restoring force corresponding to this expansion is created in the elastic material. During the idle operation state, this restoring force provides the pressure by which permeate is pressed out of the container made of elastic material and from the permeate conduit into the second chamber 22 and through the membrane 11.

[0112] In the embodiment shown in FIG. 2, the container made of elastic material is provided in the form of a flexible tube 41 which is connected to the permeate conduit 3 via a conduit 43. Flexible tube 41 may in particular be a silicone tube. The container 41 made of elastic material and arranged at the end on conduit 43 is equipped with a pressure monitoring valve 411 which opens when a pressure is reached in the container 41, which exceeds a threshold based on the expansion properties of the elastic material.

[0113] In the embodiment as shown in FIG. 3, this safety function is integrated in the second passage 51 of the shut-off valve. The pressure vessel is in the form of a container 40 made of elastic material, for example a silicone tube, which is flowed through during the operation state. The container 40 made of elastic material fills with purified water and the elastic material expands. In the idle operation state, with the valve 81 closed, this expansion will be undone due to the restoring force and the permeate will be pressed back from the container 40 through the permeate conduit 3 into the second chamber 22 and through the membrane 11.

[0114] The diameter, length, and wall thickness of the containers 40, 41 are dimensioned in such a manner, in particular adapted to the flow resistance of the permeate conduit and the reverse osmosis container as well as to the osmotic pressure, that in the extraction operation state a sufficiently large restoring force builds up in the elastic material to ensure backflushing of the membrane during the idle operation state.

[0115] FIG. 5 illustrates an under-counter reverse osmosis system 1000 that is operated with an additional pressure tank 400. This additional pressure tank 400 is arranged on the permeate side downstream of the under-counter reverse osmosis system 1000 and upstream of valve 81 of the water faucet as seen in the flow direction. Furthermore, FIG. 5 shows a pressure booster pump 500 upstream of the raw water 1 inlet of the under-counter reverse osmosis system 100. This pump may also be provided as an alternative to the additional pressure tank 400.

[0116] According to an advantageous embodiment it is contemplated that the entire system is encased such that the under-counter reverse osmosis system 1000, optionally together with a pressure booster pump 500 and/or an additional pressure tank 400 including a backflow preventer 450 are accommodated in a housing.

[0117] FIG. 6 shows a schematic diagram of a preferred embodiment of a reverse osmosis container in the form of a filter candle 100 in a sectional view. This filter candle comprises a stationarily installed base unit 101 and a reverse osmosis device in the form of an exchangeable unit 102 which comprises a plastic housing 103 having a base 103a and an head portion 103b.

[0118] Housing 103 accommodates a reverse osmosis membrane in the form of a cylindrical coil 104 which has a first end face 104a and a second end face 104b. The permeate collecting tube 105 is located in the center of the coil. Coil 104 is coupled to the head portion 103b by adapter 106. Adapter 106 provides inlets and outlets for inflowing water and for exiting permeate and concentrate, respectively, namely inlet opening 107, outlet opening 108, and outlet opening 109. Furthermore, the adapter provides inlet passage 107a and outlet passages 108a and 109a, with passage 108a connecting the outlet opening 108 with the permeate collecting tube 105, while the concentrate is fed to the outlet opening 109 via outlet passage 109a.

[0119] The exchangeable unit 102 is coupled to the base unit 101 by screwing. For this purpose, the base unit 101 has the internal thread 110, the exchangeable unit 103 has the external thread 111. In the area of outlet openings 108 and 109, seals 112 and 114 are located between base unit 101 and exchangeable unit 102. A further seal 113 is located in the area of threads 110 and 111.

[0120] The base unit 101 has an inlet 115 for salty water to be purified in the exchangeable unit 102, an outlet 116 for permeate produced in the exchangeable unit, and an outlet 117 for concentrate produced in the exchangeable unit 102. If, as shown, the exchangeable unit 102 is screwed into the base unit 101, inlet 115 is coupled to inlet opening 107, outlet 116 is coupled to outlet opening 108, and outlet 117 is coupled to outlet opening 109.

[0121] The base unit 101 may furthermore comprise blending means 118 and/or 123 and optionally control means 119. Blending means 118 allows to admix salty water entering the base unit 101 via inlet 115 to the permeate emerging from the reverse osmosis device 102. Blending device 123 allows to admix concentrate to the permeate emerging from the reverse osmosis device 102. Control means 119 allows to control the flow rate of concentrate emerging from the reverse osmosis device 102 and thus indirectly the production of permeate in the reverse osmosis device 102.

[0122] The flow direction of the water to be purified and of the resulting permeate and concentrate within the device 100 is indicated by arrows. During operation, salty water enters the base unit 101 via inlet 115. From there, the water is fed through inlet opening 107 and into the exchangeable unit 102 of the reverse osmosis container in the form of a filter candle, where it flows through the inlet passage 107a and through a gap between the jacket 121 of the cylindrical coil 104 and the inner wall surface 122 of the pressure vessel and towards the second end face 104b and then flows axially through the coil towards the first end face 104a, whereby permeate and concentrate are produced.

[0123] While the permeate is discharged via permeate collecting tube 105, the concentrate emerges from the first end face 104a of the cylindrical coil 104. Permeate from the permeate collection tube 105 can enter the base unit 101 upwards through passage 108a and via outlet opening 108. Here it reaches an annular cavity 120 which is enclosed by the base unit 101 and the exchangeable unit 102. From there it is fed to outlet 116. The concentrate emerging from the first end face 104a of cylindrical coil 104 flows through outlet passage 109a to the outlet opening 109 which opens into base unit 101. There it is fed to the outlet 117. The amount of concentrate emerging from outlet 117 can be controlled by control means 119 which will usually be a valve.

[0124] It will be apparent to a person skilled in the art that the invention is not limited to the exemplary embodiments described above, but can rather be varied in multiple ways. The individual features of the illustrated examples may in particular be implemented in combination or may be exchanged for one another or supplemented by further features.

LIST OF REFERENCE NUMERALS:

[0125] 1 Input water conduit, raw water, water to be purified, feed

[0126] 2 Reverse osmosis container

[0127] 21 First chamber of reverse osmosis container

[0128] 22 Second chamber of reverse osmosis container

[0129] 100 Reverse osmosis container in the form of a filter candle

[0130] 101 Stationarily installed base unit

[0131] 102 Reverse osmosis device in the form of an exchangeable unit

[0132] 103 Housing

[0133] 103a Base of housing

[0134] 103b Head portion of housing

[0135] 104 Coil

[0136] 104a First end face of coil

[0137] 104b Second end face of coil

[0138] 105 Permeate collecting tube

[0139] 106 Adapter

[0140] 107 Inlet opening for inflowing water

[0141] 107a Inlet passage for inflowing water

[0142] 108 Outlet opening for outflowing permeate

[0143] 108a Outlet passage for outflowing permeate

[0144] 109 Outlet opening for outflowing concentrate

[0145] 109a Outlet passage for outflowing concentrate

[0146] 110 Internal thread

[0147] 111 External thread

[0148] 112 Seal

[0149] 113 Seal

[0150] 114 Seal

[0151] 115 Inlet for salty water to be purified

[0152] 116 Outlet for produced permeate

[0153] 117 Outlet for produced concentrate

[0154] 118 Blending means

[0155] 123 Blending means

[0156] 119 Control means

[0157] 121 Jacket

[0158] 122 Inner wall surface

[0159] 3 Permeate conduit, conduit for purified water

[0160] 4 Pressure tank, pressure vessel; or reservoir with pump

[0161] 40 Through flow pressure accumulator; container made of elastic material, flexible silicone tube

[0162] 41 Terminal pressure accumulator; container made of elastic material, flexible silicone tube

[0163] 43 Conduit between pressure tank and permeate conduit, conduit between pressure tank and outlet for purified water

[0164] 5 Shut-off valve, stop valve

[0165] 50 First passage

[0166] 51 Second passage

[0167] 55 Switching means, piston with diaphragm plate and further diaphragm

[0168] 6 Concentrate conduit

[0169] 7 Wastewater

[0170] 8 Kitchen worktop, table

[0171] 80 Faucet

[0172] 81 Faucet valve

[0173] 9 Absorption means, especially for disinfectants such as chlorine, e.g. activated carbon block

[0174] 10 Device for purifying drinking water

[0175] 11 Semipermeable membrane

[0176] 1000 Under-counter reverse osmosis system

[0177] 400 Additional pressure tank on permeate side

[0178] 450 Check valve

[0179] 500 Pump for conveying raw water in the feed conduit