JP2002361244A - Softening device for city water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a softening device for city water which is small in size and can economically and continuously supply soft water. SOLUTION: This device is equipped with a plurality of small-size softening tanks 1, 2 selectively used to soften city water and a salt tank 24 commonly used to selectively supply regenerated brine to the softening tanks 1, 2 to recover the ion exchange power of ion exchange resin particle layers 3, 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a tap water softening apparatus.

[0002]

2. Description of the Related Art Generally, tap water is used as domestic living water. Tap water contains hardness components such as calcium ions and magnesium ions.If detergent is used, soap scum adheres and hands become rough, white clumps adhere to electric pots, etc. There is a problem that soap scum adheres to a washing machine or a basin.

[0003] Such a problem is described in Japanese Patent Application Laid-Open No. 6-15265.
As described in Japanese Patent Application Laid-Open Publication No. H10-260, the problem can be solved by softening tap water using a water softener using an ion exchange resin.

[0004]

However, a tap water softening apparatus that performs a regeneration process for restoring the ion removal ability of an ion exchange resin based on a timer or a water flow rate wastes the regenerated salt water used for the regeneration process. Will be
There is a problem that the operating cost increases. Further, in the water softening device using a single water softening tank, there is an inconvenience that soft water cannot be supplied during the regeneration period.

An object of the present invention is to provide a tap water softening apparatus which can realize a small and continuous soft water supply.

It is another object of the present invention to provide a tap water softening apparatus capable of efficiently realizing soft water supply using a small amount of ion exchange resin particles.

Still another object of the present invention is to provide a tap water softening apparatus capable of realizing a reasonable soft water supply at a low operating cost by optimizing the amount of salt used for regenerating the function of ion exchange resin particles. It is to realize.

[0008]

SUMMARY OF THE INVENTION The present invention provides a water softening water supply system that softens water by passing received tap water through a water softening tank filled with an ion-exchange resin particle layer, and the water softening tank. Tap water soft water comprising: a regeneration system that restores the ion exchange capacity of the ion exchange resin particles by supplying salt water to the ion exchange resin particle layer and passing it through the ion exchange resin particle layer; and a control system that controls the water softening water supply system and the regeneration system. In the water softening device, the water softening water supply system includes a plurality of water softening tanks connected in parallel,
A tap water supply solenoid valve that switches a tap water passage so as to selectively pass tap water to the plurality of water softening tanks, and the regenerating system disperses regenerated salt water generated by dissolving salt into the plurality of salt water. A regenerated salt water supply solenoid valve that switches a regenerated salt water passage to selectively pass water to the water softening tank, wherein the control system includes:
An outflow hardness detection sensor that detects the hardness of the softened outflow water, and referring to the detection signal of the outflow hardness detection sensor, when the outflow hardness is equal to or more than a predetermined value, the water softening tank through which the tap water flows is separated. A control device is provided for switching the water supply electromagnetic valve so as to switch to the water softening tank, and for switching the regenerated salt water supply electromagnetic valve so as to pass the regenerated salt water to the water softening tank that has passed water.

[0009]

Embodiments of the present invention will be described. FIG. 1 is a piping diagram of a tap water softening apparatus showing one embodiment of the present invention.

[0010] The tap water softening apparatus according to this embodiment includes a water softening water supply system having two water softening tanks containing ion exchange resin particle layers, and selectively alternates one of the two water softening tanks. Used to soften tap water and supply water. Then, the regeneration system for restoring the water softening ability of the ion exchange resin particle layer built in each water softening tank selectively supplies the regenerated salt water generated by one regenerated salt water generating means to the water softening tank in the rest state. Thereby, regeneration of the ion exchange resin particle layer built in the water softening tank is realized. In the two water softening tanks in this embodiment, one water softening tank is configured to have a large (long-term treatment) capacity for main water softening water supply, and the other water softening tank regenerates the one water softening tank. The amount of ion exchange resin particles incorporated in the other water softening tank is reduced by configuring the capacity to be small (short term treatment) only to assist the water softening water supply during the period, and a small amount of ion exchange The resin particle layer is used efficiently so that continuous softening water supply can be realized. The control system for performing such water softening water supply and regeneration detects the hardness of tap water received by various measuring means, the hardness of soft water discharged after softening, the amount of water flow, and the concentration of regenerated salt water. Rationally realizes water softening water supply and regeneration. The large-capacity water softening tank may be configured to have a large capacity by using a plurality of water softening tanks.

In FIG. 1, two water softening tanks 1 and 2 each having a tubular and hermetically sealed structure have ion-exchange resin particle layers 3 and 4 each having a water-passing ability in a middle section, and tap water in a lower section. Water receiving chambers 5 and 6 are provided, and soft water discharge chambers 7 and 8 are provided in the upper stage. The water softening tank 1 and the ion exchange resin particle layer 3 are configured to have a large water softening treatment capacity for realizing main water softening water supply, and the water softening tank 2 and the ion exchange resin particle layer 4 are formed of the ion exchange resin of the water softening tank 1. The water softening treatment capacity is sufficient to realize auxiliary water softening water supply during regeneration of the particle layer 3.

The water supply pipe 9 is provided so as to supply tap water (raw water) to the internal water supply pipe 13 via a shutoff valve 10, a branch pipe 11, and a shutoff valve 12. Internal water receiving pipe 13
Adjusts tap water to a predetermined water pressure by a pressure reducing valve 14,
Raw water hardness detection sensor 1 that detects the hardness of tap water (raw water) and outputs a raw water hardness signal after intervening check valve 15.
6 and further selectively supply water to the tap water receiving chambers 5 and 6 of the water softening tanks 1 and 2 via the water supply solenoid valves 17 and 18, and the backwash solenoid valves 19 and 21 and the rinsing solenoid valves. The soft water discharge chambers 7, 8 of the water softening tanks 1, 2 are interposed in parallel with each other.
And a pipe for supplying water to the salt tank 24 via the salt water generation solenoid valve 23.

From the water supply solenoid valves 17 and 18 to the water softening tanks 1 and 2
Tap water (raw water) supplied to the tap water receiving chambers 5, 6 of
The water is softened by passing through the ion-exchange resin particle layers 3 and 4 and reaches the soft water discharge chambers 7 and 8. This soft water discharge room 7,
The tap water (soft water) of No. 8 is supplied to the soft water supply pipe 29 through the check valves 25 and 26 and the water supply solenoid valves 27 and 28, and is supplied through the flow rate sensor 30, the closing valve 31, the branch pipe 32, and the closing valve 33. Pipes to supply tap water (soft water) to the water supply pipe 32. In this embodiment, they constitute a water softening water supply system.

A soft water hardness detection sensor 35 is connected in the middle of the soft water supply pipe 29. This soft water hardness detection sensor 3
The raw water hardness detection sensor 5 and the raw water hardness detection sensor 16 can be configured using a sensor that measures the electric resistance value of water.

The salt tank 24 contains purified salt or tablet-like salt 36, and is provided with the salt water generating electromagnetic valve 2
The regenerating salt water supply electromagnetic wave is supplied to the salt tank 24 through the feed line 3 to dissolve the salt 36, thereby generating a salt water having a predetermined concentration, and selectively opening the salt water while detecting the concentration of the salt water detected by the salt concentration detection sensor 37. Valves 38 and 39 and check valve 4
0, 41, the soft water discharge chambers 7 of the water softening tanks 1, 2;
A pipe is provided so as to selectively supply the regenerated salt water to 8. The regenerated salt water supplied to the water softening chambers 7, 8 of the water softening tanks 1, 2 passes through the ion exchange resin particle layers 3, 4, and flows down to the raw water receiving chambers 5, 6. The regenerated salt water flowing down to the raw water receiving chambers 5 and 6 is connected to the drain pipe 44 via the drain solenoid valves 42 and 43 so as to be drained. Further, the soft water discharge chambers 7 and 8 of the water softening tanks 1 and 2 are piped so as to drain water to the drain pipe 44 via cleaning and drain solenoid valves 45 and 46. In this embodiment, these constitute a reproduction system.

In the middle of the drain pipe 44, a salt concentration detection sensor 47 is connected.

The control device 51 is mainly composed of a microcomputer, and receives instructions from an operation panel 52, inputs detection signals from various detection sensors 16, 30, 35, 37 and 47, and uses its own timer function. With reference to the aging signal, various solenoid valves 17, 18, 19, 2
0, 21, 22, 23, 27, 28, 38, 39, 4
2, 43, 45, and 46 are executed, and the operation state is displayed on the operation panel 52. In the present embodiment, these constitute a control system.

The bypass water supply valve 48 is a valve that is opened when water is supplied without using the tap water softening device. The bypass water supply valve 48 may be in the form of either a solenoid valve or a manual valve. However, in consideration of an emergency operation, a manual valve or a solenoid valve which is opened when a power failure occurs is preferable.

Next, the operation control of the tap water softening apparatus will be described with reference to a time chart shown in FIG. Here, first, the water softening tank 2 is regenerated while using the water softening tank 1 to provide water softening water (water supply to the A system).
An operation in which the water softening tank 1 is regenerated while using the water softening tank 2 while water softening water supply (B system water supply) is performed, and when the regeneration of the water softening tank 1 is completed, the operation returns to the water softening water supply using the water softening tank 1. The control will be described. Such operation control of water softening water supply and regeneration is repeatedly executed thereafter.

In the water supply of the A system, the control device 51 opens the water supply electromagnetic valve 17 and the washing and drainage electromagnetic valve 45 by a manual operation and an automatic control using a timer at the time of start-up and after a long period of inactivity. The tap water whose pressure has been adjusted is supplied to the raw water receiving chamber 5 of the water softening tank 1, passed through the ion exchange resin particle layer 3, and sent out to the soft water discharge chamber 7.
The inside of the water softening tank 1 is flush-washed by draining to the water distribution pipe 44. Thereafter, by opening the water supply solenoid valves 17 and 27, the softened tap water (soft water) of the soft water outlet chamber 7, which has passed through the ion exchange resin particle layer 3 and is softened, is sent out to the water supply water pipe 34 and opened. Drain soft water from the faucet (faucet). At this time, the hardness of the soft water is detected by the soft water hardness detection sensor 35, the flow rate of the discharged water is detected by the flow rate detection sensor 30, and the control device 51 recognizes the operation state by inputting these detection signals to perform various controls. Execute.

Then, during the A system water supply period, the water softening tank 2 in the B system is regenerated. For this regeneration, the controller 51 opens the salt water generation electromagnetic valve 23 for a predetermined time and supplies a predetermined amount of tap water to the salt tank 24. When the time when the tap water supplied into the salt tank 24 dissolves the salt 36 and reaches the predetermined concentration of salt water has elapsed, the drain solenoid valve 43 is opened and the water softening tank 2 is opened. The interior of the water softening tank 2 is opened by opening the backwashing electromagnetic valve 21 and backflowing the tap water from the soft water discharge chamber 8 to the raw water receiving chamber 6 with respect to the ion exchange resin particle layer 4 in the water softening tank 2. 2, the backwashing electromagnetic valve 21 is closed, the regenerated salt water supply electromagnetic valve 39 is opened, and the regenerated salt water of a predetermined concentration generated in the salt tank 24 is supplied to the water softening tank 2 for ion exchange. By passing through the resin particle layer 4, the water softening ability of the ion exchange resin particle layer 4 is restored.

The valve opening time of the regenerated salt water supply solenoid valve 39 is set to a time for supplying an appropriate amount of regenerated salt water to restore the ion exchange capacity of the ion exchange resin particle layer 4. The supply flow rate of the regenerated salt water is desirably set so that the supplied regenerated salt water uniformly penetrates the ion-exchange resin particle layer 4 and then is drained.

After the supply of the regenerated salt water is completed, the rinsing solenoid valve 22 is opened to allow tap water to pass through the ion-exchange resin particle layer 4 to rinse the ion-exchange resin particle layer 4. Drain to drain pipe 44. The rinsing is performed for about 60 minutes with a small flow rate (about 0.3 L / min) of rinsing water. The flow rate and the rinsing time are preferably set according to the amount of ion exchange resin particles used.

After a lapse of a settling time after completion of the rinsing, the water supply solenoid valve 18 and the washing / draining solenoid valve 46 are opened, and water is passed in a pure direction into the water softening tank 2 for washing. End playback.

In this regeneration control, the amount of the regenerated salt water supplied to the water softening tank 2 may be determined by a fixed time control using a timer, but may be determined based on the difference in the salt concentration detected by the salt concentration detection sensors 37 and 47. If the control is performed while monitoring the degree of recovery of the exchange resin particle layer 4, the regenerated salt water can be used efficiently.

The water supply by the A system is continued by the control device 51 based on the detection signals of the hardness detection sensors 16 and 35 and the flow rate sensor 30, and when the hardness of the soft water to be discharged rises to a predetermined hardness, or when the raw water and the water are discharged. Is switched to the B-system water supply when the difference in hardness of the water drops below a predetermined value (when the water softening ability decreases) or when the water supply reaches a predetermined water supply amount.
This switching is performed by the supply water electromagnetic valve 18 and the washing drain electromagnetic valve 46.
Is opened, the inside of the water softening tank 2 is flush-cleaned, the cleaning / draining electromagnetic valve 46 is closed, the water supply electromagnetic valve 28 is opened, and the water supply electromagnetic valves 17 and 27 are closed.

Then, regeneration of the water softening tank 1 of the system A is executed during the water supply period of the system B, which is switched to the water softening using the water softening tank 2. For this reproduction control, the controller 51
Opens the salt water generation electromagnetic valve 23 for a predetermined time and supplies a predetermined amount of tap water to the salt tank 24. And salt tank 24
When the time when the tap water supplied into the tank dissolves the salt 36 and reaches the predetermined concentration of salt water has elapsed, the drain solenoid valve 42 is opened to drain the water in the water softening tank 1 before that. The backwashing solenoid valve 19 is opened, and the tap water is caused to flow back from the soft water discharge chamber 7 to the raw water receiving chamber 5 with respect to the ion-exchange resin particle layer 3 in the water softening tank 1 to backwash the softening tank 1. After that, the backwashing electromagnetic valve 19 is closed and the regenerated salt water supply electromagnetic valve 38 is opened to supply the regenerated salt water of a predetermined concentration generated in the salt tank 24 to the water softening tank 1 and the ion exchange resin particle layer 3
To recover the water softening ability of the ion exchange resin particle layer 3. The valve opening time of the regenerated salt water supply electromagnetic valve 38 is set to a time for supplying an appropriate amount of regenerated salt water for restoring the ion exchange capacity of the ion exchange resin particle layer 3. The supply flow rate of the regenerated salt water is desirably set so that the supplied regenerated salt water uniformly penetrates the ion-exchange resin particle layer 3 and is then drained. After the supply of the regenerated salt water is completed, the rinsing solenoid valve 20 is opened to allow tap water to pass through the ion-exchange resin particle layer 3 to rinse the ion-exchange resin particle layer 3,
The rinsing water is drained to a drain pipe 44 via a drain solenoid valve 42. This rinsing is performed slowly with a small flow of rinsing water. Then, after a lapse of the settling time after the rinsing, the water supply solenoid valve 17 and the washing drainage solenoid valve 45 are opened to open the water softening tank 1.
By flowing water in the pure direction into the inside and washing it, the water softening tank 1
End playback of.

In this regeneration control, the amount of the regenerated salt water supplied to the water softening tank 1 may be determined by a fixed time control using a timer, but the amount of the regenerated salt water is determined based on the difference in the salt concentration detected by the salt concentration detection sensors 37 and 47. When configured to control while monitoring the degree of recovery of the exchange resin particle layer 3, the regenerated salt water can be used efficiently.

The B-system water supply is supplied to the control unit 51.
Continues based on the detection signals of the hardness detection sensors 16 and 35 and the flow rate sensor 30, and when the hardness of the soft water to be discharged increases to a predetermined hardness or when the hardness difference between the raw water and the water decreases to a predetermined value or less ( When the water softening capacity is reduced) or when a predetermined water supply amount is reached, the system is switched to system A water supply. This switching is performed by opening the water supply electromagnetic valve 17 and the washing and draining electromagnetic valve 45 to flush flush the inside of the water softening tank 1, closing the washing and draining electromagnetic valve 45, opening the water supply electromagnetic valve 27, and closing the water supply electromagnetic valves 18 and 28. This is achieved by: The B system water supply period is a relatively short period for assisting the water softening water supply during the period in which the regeneration of the water softening tank 1 of the A system is executed.

The switching between the A-system water supply and the B-system water supply may be performed manually, based on the usage time or at a fixed time.

As described above, the control device 51 supplies the softened water to the water supply water pipe 34 mainly by using the water softening tank 1 by controlling the water supply solenoid valves 17, 18, 27, and 28, thereby softening the water. When the tank 1 is regenerated, the water softening tank 2 is used as an auxiliary to continuously supply soft water to the water supply water pipe 34,
After the regeneration of the water softening tank 1 is completed, the water softening tank 1 is again supplied with water for softening, and the water softening tank 2 is regenerated and put on standby. Continuous softening water supply can be achieved using the particles.

The water softening tanks 1 and 2 are switched when the hardness of the soft water to be discharged rises to a predetermined hardness or when the hardness difference between the raw water and the water decreases to a predetermined value or less (the water softening ability is reduced). ) Or when a predetermined amount of water is supplied, the tap water is processed into soft water having a preferable hardness by using the water softening tanks 1 and 2 efficiently to continuously supply water. be able to.

One regenerating system (regenerating salt water generating means)
Is re-distributed selectively to the two water softening tanks 1 and 2 to restore the water softening ability of the ion exchange resin particle layers 3 and 4 in the water softening tanks 1 and 2. With such a configuration, a small-sized reproduction system can be realized.

The amount of the regenerated salt water supplied to the water softening tank 1 is controlled based on the difference between the salt concentrations detected by the salt concentration detection sensors 37 and 47, so that the regenerated salt water can be used efficiently. The operation cost can be reduced by reducing the consumption of the purified salt.

In the embodiment described above, the water softening tank 1
The water softening tank 1 is used for the main water softening water supply by increasing the amount of the ion-exchange resin particle layer 3 built in the water softening tank 2, and the water softening tank 2 is reduced in the amount of the built-in ion exchange resin particle layer 4 by the soft water Tank 2 was used for auxiliary water softening water supply, but the same amount of ion-exchange resin particle layers 3 and 4 contained in the two water softening tanks 1 and 2 were alternately provided with equal amounts of tap water. May be configured to be subjected to a water softening treatment.

Further, by equalizing the amounts of the ion-exchange resin particle layers 3 and 4 contained in the two water softening tanks 1 and 2 and sharing them in a parallel state to perform softening treatment, it is possible to supply softened water having a rated water amount. The water softening capacity can be realized, and the water can be regenerated alternately at a small amount of water supply. With this configuration, it is possible to realize continuous water softening water supply by efficiently using a small amount of ion exchange resin particles as a whole. The water softening device having such a configuration can reduce the flow rate of water through the water softening tanks 1 and 2, and is therefore particularly effective as a water softening device for softening tap water having high hardness.

As shown in FIG. 3, each of the water softening tanks 1 and 2 has a cavity (water receiving chamber 5) at the upper end in a vertically long cylindrical closed container 61. To form an ion-exchange resin particle layer 3, a water supply pipe 63 having a strainer 62 attached at the tip was inserted into the water receiving chamber 5 at the upper end, and a strainer 64 was attached to the tip. The water discharge pipe 65 may be buried in the ion-exchange resin particle layer 3, and the strainer 64 may be inserted so as to reach near the bottom in the closed container 61. In such a water softening tank 1, the strainer 64
The inside of the water discharge pipe 65 inserted into the closed container 61 constitutes the water discharge chamber 7.

The water supply pipe 63 is provided with a water supply solenoid valve 17.
And the drain electromagnetic valve 42, and the backwash electromagnetic valve 19, the rinse electromagnetic valve 20, and the check valve 25 are connected to the water discharge pipe 65.

[0039]

According to the present invention, continuous soft water supply can be realized by a small tap water softening device constituted by using a plurality of small water softening tanks and a common regenerating salt water generating means. In particular, by configuring one water softening tank for main water softening water supply and the other water softening tank for auxiliary water supply during regeneration, the total amount of ion exchange resin particles is reduced. It can be an economical tap water softening device.

Further, by using a plurality of water softening tanks in parallel and sharing water softening treatment, a water softening treatment capacity capable of supplying softened water with a rated water amount is realized, and the water softening treatment is alternately performed when the water supply amount is small. By regenerating, it is possible to efficiently use a small amount of ion-exchange resin particles as a whole, and realize continuous softening and supply of high-hardness tap water.

In addition, it is possible to realize a reasonable supply of soft water at a low operation cost by optimizing the amount of the regenerated salt water.

[Brief description of the drawings]

FIG. 1 is a piping diagram of a tap water softening apparatus showing an embodiment of the present invention.

FIG. 2 is an example of a time chart of operation control of the tap water softening apparatus shown in FIG.

FIG. 3 is a vertical sectional side view specifically showing one example of a water softening tank in the tap water softening apparatus shown in FIG.

[Explanation of symbols]

1,2 ... water softening tank, 3,4 ... ion exchange resin particle layer, 1
6: Raw water hardness detection sensor, 17, 18, 27, 28: Water supply solenoid valve, 24: Salt tank, 30: Flow rate detection sensor, 3
5 ... Soft water hardness detection sensor, 36 ... Salt, 37, 47 ... Salt concentration sensor, 51 ... Control device.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B01J 49/00 B01J 49/00 W X (72) Inventor Akira Nakasuji Akira Nishihara 1450, Osaki, Azuma, Hitachinaka City, Ibaraki Prefecture Ground Hitachi Electric Systems Co., Ltd. (72) Inventor Tetsuo Matsuoka Ibaraki Pref. Ground F-term in Hitachi Electric Systems Co., Ltd. (Reference) 4D025 AA02 AB19 BA07 BA22 BB08 BB10 CA01 CA10

Claims (8)

[Claims] 1. A water softening water supply system in which tap water received is passed through a water softening tank filled with an ion exchange resin particle layer to soften and output water, and a salt water is supplied to the water softening tank to perform ion exchange. A tap water softening device comprising a regeneration system for restoring the ion exchange capacity of the ion exchange resin particles by passing through a resin particle layer, and a control system for controlling the water softening water supply system and the regeneration system; The system includes a plurality of water softening tanks connected in parallel, and a tap water supply solenoid valve that switches a tap water passage to selectively supply tap water to the plurality of water softening tanks. A regenerated salt water supply solenoid valve that switches a regenerated salt water flow passage so as to selectively pass regenerated salt water produced by dissolving salt to the plurality of water softening tanks; Water hardness detection to detect hardness With reference to the sensor and the detection signal of the water hardness detection sensor, when the water hardness is equal to or more than a predetermined value, the water supply solenoid valve is switched so that the water softening tank through which tap water flows is switched to another water softening tank. A tap water softening device, comprising: a control device that switches the regenerated salt water supply electromagnetic valve so that the regenerated salt water flows into the water softening tank that has finished passing water. 2. The water supply system according to claim 1, wherein said regeneration system is configured to selectively distribute the regenerated salt water generated in one regenerated salt water tank to one of a plurality of water softening tanks. Water softener. 3. The control system according to claim 1, wherein the control system includes a tap water hardness detection sensor for detecting hardness of the received tap water, and the control device is configured to output the tap water based on the tap water hardness. A tap water softening device characterized in that a water supply solenoid valve is switched so that a softening tank through which tap water flows is switched to another softening tank when the hardness is equal to or more than a predetermined value. 4. The tap water soft water according to claim 1 or 2, wherein the control system includes a water discharge amount detection sensor for measuring a water discharge amount, and controls a flow rate of the regenerated salt water according to the water discharge amount. Device. 5. The control system according to claim 1, wherein the control system includes a salt concentration detecting sensor for detecting a salt concentration of the regenerated salt water supplied to the water softening tank and a salt concentration of the regenerated salt water discharged from the water softening tank. A tap water softening apparatus characterized in that a regeneration state of ion exchange resin particles is detected based on a difference in salt concentration to control regeneration. 6. The water softening apparatus according to claim 1, wherein one of said plurality of water softening tanks is configured to have a small capacity and used when regenerating another water softening tank. A tap water softening device characterized in that: 7. The control system according to claim 1, wherein:
A tap water softening apparatus characterized in that tap water is passed in parallel to a plurality of water softening tanks to supply water softening water, and a solenoid valve is controlled so as to alternately regenerate the water during a time when the flow rate is small. 8. The control system according to claim 1, wherein the control system drains water that has passed through the ion-exchange resin particle layer when tap water is passed through the water softening tank to start soft water supply. A tap water softening device characterized by controlling an electromagnetic valve so as to flush the inside of the water softening tank by flushing.