JP3162563B2 - Variable flow path drainage basin and method of switching the drainage basin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable drainage basin interposed in a pipe such as a home drainage pipe.

[0002]

2. Description of the Related Art Conventionally, a drainage basin is provided with an inlet-side mouth at the beginning of a water flow path formed at the bottom and an outlet-side mouth at the end of the water passage. The upstream pipe and the downstream pipe are connected. In addition to the drainage basin, there is a type in which the water flow path is straight, and a type in which the water flow path is bent. Different drainage basins of these types are used depending on the direction in which the downstream pipe extends. Can be

On the other hand, when a new public sewer is installed in an area where a sewer pipe with a drainage basin has been laid, the downstream pipe connected to the outlet of the drainage basin extends. When the direction changes,
After digging the ground and removing the drainage basin and pipes that were used up to now, bury a new drainage basin of the type where the position of the outlet side coincides with the direction of extension of the downstream pipe and the pipe connected to it It was necessary to fix it.

[0004]

However, when replacing pipes as described above, digging the ground to remove drainage basins and pipes that have been used up to now, or replacing new drainage basins with new ones. When burying a pipe,
There were many problems, such as the total construction cost associated with the replacement of the pipeline, the construction was large, and the construction period was long.

[0005] The present invention has been made in view of the above problems, and in the case where the installation of public sewerage or the like is planned in the future or the replacement of drainage pipes is considered, two types of pipes are required in advance. By laying it down, it is possible to switch the direction of the flow path only by working in the internal space of the drainage basin that is buried in the ground, without having to dig or bury the ground The purpose of the present invention is to provide a variable flow path drainage basin and a flow path switching method for a variable flow path drainage basin, which can be used to continuously replace a drainage basin which has been used until now. I do.

[0006]

According to a first aspect of the present invention, there is provided a variable drainage basin according to the present invention, wherein a first opening on an inlet side and an outlet side communicating with an inner space at an intermediate portion in a height direction, and a bottom portion in the inner space. The main body has a second mouth portion communicating with the first mouth portion, and a separable pipe body disposed between the first mouth portions on the inlet side and the outlet side.

According to a second aspect of the present invention, there is provided a method of switching a flow path of a drainage basin using the variable drainage basin according to the first aspect, wherein the first port on an inlet side and an outlet side are provided. The pipes are arranged between the parts to form pipes passing through the mouths, and the pipes are closed from the second mouths by the pipes. After dividing the pipe at a predetermined location in the space, the first port on the inlet side is removed through the internal space of the box body by removing the remaining pipe at the first port on the inlet side. In the second state.

According to a third aspect of the present invention, there is provided a method of switching a drainage basin using the variable drainage basin according to the first aspect of the present invention. The pipes are arranged between the parts to form pipes passing through the mouths, and the pipes are closed from the second mouths by the pipes. After dividing a predetermined portion of the pipe body in the space, the remaining pipe body remaining at the first port on the outlet side is removed, and the pipe port of the remaining pipe body remaining at the first port on the inlet side is cut out of the box body. The second state is established so as to communicate with the second port via the internal space.

According to a fourth aspect of the present invention, there is provided a drainage basin having a variable flow path, wherein a first opening on the inlet side and an outlet side communicating with the inner space at the intermediate portion in the height direction and a second opening communicating with the inner space at the bottom. Flow switching method for a drainage basin using a drainage basin having a basin body comprising: a tub body provided between the first opening portions on the inlet side and the outlet side and capable of being divided and expanded. Wherein a pipe is provided between the first port on the inlet side and the first port on the outlet side to form a conduit passing through the ports, and the ports are connected to the second port by the pipe. First cut off from the part
From the state, by removing the pipe from the first opening on the inlet side by shrinking the pipe in the internal space of the box body, the first port on the inlet side is connected to the second port via the internal space of the box body. The second state is established so as to communicate with the mouth.

[0010]

According to the variable drainage basin according to the first aspect of the present invention, the pipe is disposed between the first port on the inlet side and the first port on the outlet side. When the flow path is formed by the pipe, water flows only from the first port side on the inlet side to the first port side on the outlet side via the pipe, and does not flow to the second port side. On the other hand, a predetermined portion of the pipe disposed between the first port on the inlet side and the first port on the outlet side is divided in the inside of the main body, and a predetermined portion of the pipe is formed. When removed, the water reaches the bottom of the box body through the internal space of the box body from the first port side on the inlet side or the remaining port of the pipe body remaining at the first port on the inlet side, It flows to the two mouths.

[0011] Further, the above-mentioned dividing operation of the tube and the operation of removing the divided tube are all performed in the internal space of the box body.

According to the method for switching a drainage basin according to the second and third aspects of the present invention, since all of the pipe cutting work is performed in the internal space of the basin body, the first state is changed to the second state. There is no need to dig or backfill the buried area of the drainage basin when performing the work of switching the channel.

According to the method of switching the flow path of the drainage basin according to the invention, the work of contracting the pipe and removing the pipe from the first opening on the inlet side is performed in the internal space of the basin body. When performing the operation of switching the flow path from the first state to the second state, it is not necessary to dig or bury the place where the drainage basin is buried.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a variable drainage basin according to an embodiment of the present invention will be described.

FIG. 1 shows a box body 1 made of synthetic resin and a tube 3 attached to the box body 1 constituting the drainage box. The basin main body 1 has a bottomed cylindrical shape, and cylindrical first mouth portions 12 and 13 are protruded at two circumferential positions of the body wall 11 (that is, two circumferential positions at a middle portion in the height direction). I have. Of these, the first port 12 on the right side is used as an entrance port, and the first port 13 on the left is used as an exit port. Also,
A large-diameter portion 14 is formed at the base of the first mouth portion 12 on the inlet side, while the first mouth portion 13 on the outlet side has substantially the same inner peripheral diameter as the large-diameter portion 14. In addition, an inner flange 15 is provided at the base of the first opening 13 on the outlet side, and the inner diameter of the inner flange 15 is the same as the inner diameter of the first opening 12 on the inlet side. It is almost the same. In this embodiment, the first opening 12 on the entrance side and the first opening 13 on the exit side have the same axial center. Further, a groove 16 serving as a water flow path is formed at the bottom of the basin body 1, and a second port 17 communicating with the groove 16 is provided at the bottom. As the tube 3, a synthetic resin tube (for example, a PVC tube) cut to a predetermined length is used. Therefore, this pipe 3 can be cut by cutting it at an arbitrary position using a predetermined tool. In addition, the 1st opening part 12,1 of an entrance side and an exit side
In addition to those having the same axis 3, the axes of the first ports on the inlet side and the outlet side may cross each other at 45 degrees or 90 degrees. The body 3 becomes a curved tube bent at an angle corresponding to the intersection angle.

FIG. 5 shows the first opening 13 on the exit side of the drainage basin.
The cap body 5 made of a synthetic resin that can be mounted on the rim is shown. The cap body 5 is fitted inside the inner flange 15 of the first opening 13 on the outlet side, and is used to close the opening surrounded by the inner flange 15. Such a cap body 5 can be attached to the first opening 13 on the outlet side from the inner space S side of the box body 1. The cap body 5 is not limited to the one made of the above-mentioned synthetic resin, and may be made of rubber, wood, or an inorganic material. Can be used instead of the cap body 5.

Next, a method of switching the flow path of the drainage basin using the above drainage basin, that is, a method of switching the flow path of the drainage basin according to the embodiment of the second aspect of the present invention will be described with reference to FIGS. I do. In this embodiment, as shown in FIG. 6, before the flow path is switched, as shown by an arrow X in FIG. The second opening 17 is not used as a flow channel. After the switching of the flow path, as shown by the arrow Y in FIG.
The water that has entered through the mouth 12 comes out through the second mouth 17, and the first mouth 13 on the outlet side is set to a state that is not used as a flow path.

First, as shown in FIG.
At the same time, packing (rubber packing) 71, 72 is attached to the large-diameter portion 14 and the first opening 13 on the outlet side in FIG.
A pipe 3 made by cutting a synthetic resin pipe such as a PVC pipe into a predetermined length is inserted from the first port 13 on the outlet side, and the pipe 3 is connected to the two first ports 12, 13. It is arranged between them. In this way, the pipe 3 forms a pipe through the first ports 12 and 13 on the inlet side and the outlet side, and at the same time, the first ports 12 and 13 are formed by the pipe 3 into the second ports. The mouth 17 is cut off (cut off). This is the first state. In the first state, a margin for insertion of the inlet pipe 91 (see FIG. 2) is secured in the first mouth portion 12 on the inlet side, and the outlet pipe 92 (see FIG. 2) is secured in the first mouth portion 13 on the outlet side. 2) must be secured. Also, in places where drainage basins are to be installed for the first time, such as in newly developed residential land development sites, the first state described in FIG. Of the pipe 3 and the packing 71,
Since the mounting work of the 72 can be omitted, the construction is correspondingly simplified.

The drainage basin in the first state described with reference to FIG.
As shown in the figure, the inlet pipe 91 is inserted into the first port 12 on the inlet side, and the outlet pipe 92 is inserted into the first port 13 on the outlet side. In this way, the water flowing through the inlet pipe 91 flows out through the pipe 3 and the outlet pipe 92. Here, the inlet-side pipe 91 forms the end of a pipe extending from a location around the water such as a washroom in a house, and the outlet-side pipe 92 is provided with, for example, a public sewer planned in the future. It forms the beginning of the pipeline that drains sewage into the existing sewer for only the period up to. Until the public sewer is installed, the second mouth 17 is left unused without being used as a channel.
7, a pipe 93 (see FIG. 6) is connected in advance, and this pipe extends to a public sewer installation site scheduled in the future.

When a public sewer system is installed and it becomes necessary to flow sewage to the public sewer system, flow switching is performed. That is, as shown in FIG. 3, the pipe body 3 is cut off at a predetermined place by an operation using a predetermined cutting tool in the internal space S of the box main body 1 and divided into short sections. 3 can be removed from the first mouth portions 12 and 13. In FIG. 3, the first opening 12 on the entrance side is divided.
The remaining pipe body is indicated by reference numeral 31 and the remaining pipe body at the outlet 13 of the first port 13 is indicated by reference numeral 32. In FIG. Tube body rest 3
1 shows a state in which 1, 32 has been removed and removed from the inner space S side of the box body 1. As shown in FIG.
The first port 12 on the inlet side and the first port 13 on the outlet side after removing 2 from the first ports 12 and 13 communicate with the second port 17 via the internal space of the cell body 1. become. Therefore, as shown in FIG. 5, the cap body 5 is fitted in the first opening 13 on the outlet side in a fitting manner, and the first opening 13 is closed. At the same time, the packing 71 provided on the large-diameter portion 14 of the first opening 12 on the inlet side is removed, and a water flow guide unit 74 having a curved surface 73 for guiding the water flow as shown in FIG. Is attached in a fitting shape. As described above, the first mouth portion 12 on the inlet side communicates with the second mouth portion 17 via the internal space S of the box body 1, and the first mouth portion 13 on the outlet side is connected to the cap body 5.
As a result, it is shut off from the internal space S of the box body 1. Therefore, the water that has flowed in from the first mouth 12 on the inlet side falls to the bottom through the internal space S of the basin body 1 and is connected to the second mouth 17 through the groove 16 and the second mouth 17. It enters a pipe, from which it drains to the public sewer.

In this embodiment, although the first opening 13 on the outlet side is closed by the cap body 5, this point is, for example, the state in FIG. 3 where the remaining pipe body 32 of the first opening 13 on the outlet side is left as it is. The cap body 5 may be attached to the remaining pipe body 32 as shown in FIG. In addition, the cap body 5 has a structure in which water flowing in from the first port 12 on the inlet side is the first port 1 on the outlet side.
When the cell body 1 is large enough to not reach 3, and there is no fear that water flows into the outlet pipe 92, it is not always necessary to attach the cell.

Next, a method for switching the flow path of the drainage basin according to the third embodiment of the present invention will be described. Also in this embodiment, as described in claim 2, before switching the flow path, as shown by arrow X in FIG.
The water that has entered through the first outlet 13 exits through the first port 13 on the outlet side, and the second port 17 is not used as a flow path. Then, after the switching of the flow path, as shown by the arrow Y in FIG. 6, the water that has entered through the first opening 12 on the inlet side comes out through the second opening 17 and the water on the outlet side The one port 13 is set in a state where it is not used as a flow path.

In this embodiment, as shown in FIG. 1, the first state is achieved by arranging a pipe between the two first ports 12, 13, and the inlet side pipe as shown in FIG. 9
1 into the first opening 12 on the inlet side, and the outlet side pipe 9
2 is inserted into the first mouth portion 13 on the outlet side so that water flowing through the inlet pipe 91 flows out through the pipe 3 and the outlet pipe 92. As shown in FIG. The point that the predetermined portion of the tubular body 3 is cut off by the operation using a predetermined cutting tool in the internal space S and cut into short pieces is the same as that described in the second embodiment. In the embodiment of the third aspect, FIG.
As shown in FIG. 7, only the remaining pipe portion 32 on the outlet side is removed from the remaining pipe portions 31 and 32 remaining in the first mouth portions 12 and 13, and then removed from the cell body 1. The body 5 is fitted in a fitting manner to close the first opening 13 on the outlet side. In this way, as shown in FIG. 7, the remaining pipe 31 of the first opening 12 on the inlet side remains as it is,
Flowing from the tube body falls into the internal space S of the box main body 1 from the remaining tube body 31 and enters the groove 16 at the bottom of the box main body 1, and is connected to the second opening 17 and the second opening 17 from the groove 16. The water is drained to the public sewer through the drained pipe 93. This eliminates the need for removing the packing 71 provided on the large-diameter portion 14 of the first port portion 12 on the inlet side, and eliminates the need to attach the water flow guide unit 74.
The water falls and flows into the groove 16 directly from the remaining pipe part 31. In addition, when the tubular body remaining portion 31 is left as it is, when the tubular body 3 is cut as shown in FIG. 3, the cutting position is appropriately determined, and the inward projecting width of the tubular body remaining portion 31 is adjusted. Therefore, it is desired that the water flowing out from the remaining pipe portion 31 enter the groove portion 16 successfully.

The other points are the same as those described in the embodiment of the second aspect of the present invention.

In each of the embodiments described above, the first opening 13 on the outlet side is asymmetric with the first opening 12 on the inlet side. This point is the same as in FIG. 1
The mouth portion 13 may be provided with a large-diameter portion 18, and a packing 72 may be attached to the large-diameter portion 18.

FIG. 10 shows a drainage basin according to another embodiment of the present invention. In this drainage basin, cylindrical first mouth portions 12 and 13 are formed by first members 12 ′ and 13 ′ separate from the basin body 1, and these are integrated with the basin body 1 by means such as bonding. It has been turned. Accordingly, the body wall 11 of the basin body 1 is not provided with the first mouth portions 12 and 13 at first, and is opened using a hole saw or the like as necessary, and the first member 12 ′, 13 ′ are joined in a fitting manner to form first opening portions 12 and 13. First member 12 ', 1
Reference numeral 3 'denotes a cylindrical portion 121 and an enlarged diameter portion 122 which are concentrically connected to each other, and a flange 123 is provided on the outer periphery of the enlarged diameter portion 122. A packing 71 is attached to the inner periphery of the enlarged diameter portion 122. Have been. When the first members 12 ′ and 13 ′ are joined to the box body 1, each tubular portion 121 becomes the first mouth portion 12 or 13.

Even when the drainage basin shown in FIG. 10 is used, the pipe 3 extends over the first ports 12 and 13 in the same manner as described above.
Is provided, and the flow path can be switched by performing an operation of cutting and dividing the pipe 3.

When the drainage basin is buried in a deep place, a basin body in which cylindrical height adjusting members (adjusters) are stacked in order to provide a cleaning port on the ground may be used. In such a case, the embedding position of the inlet side pipe and the outlet side pipe matches the embedding position of the height adjusting member. Therefore, in this case, the height adjusting member 19 forming a part of the box body 1 is stacked on the bottomed box body 1 provided with the second opening 17 as shown in FIG. The height adjusting member 19 is provided with a first mouth portion 12 on the inlet side and a first mouth portion 13 on the outlet side, and these first mouth portions 12 and 1 are provided.
The flow path can be switched by arranging the tube 3 for the object 3, cutting the tube 3, or attaching the cap body 5 (see FIGS. 1 to 6).

FIG. 12 shows an example in which the first state of the second and third aspects of the present invention is formed by using a drainage basin according to still another embodiment of the first aspect of the present invention. That is, in this drainage basin, the pipe 3 is different from that described above. The tube 3 includes a pair of left and right short tubes 31 ′ and 32 ′,
The short pipe 33 interposed between these short pipes 31 ', 32'
And a slide tube 35 connecting these three short tubes 31 ′, 32 ′, 33.
It fits across 1 ', 32', and 33. Short pipe 33
Are joined so that the inner surfaces thereof are flush with each other in abutting state with the short tubes 31 ′ and 32 ′, and are held by the slide tube 35 so as not to fall off. The slide tube 35
Hold sealing materials 36, 36 such as O-rings for watertight sealing between the short pipes 31 ', 32'.

The slide tube 35 is slid left or right from the first state in FIG.
In this state, the short pipe 31 is not held and falls off. Therefore, the invention according to claim 2 can be specifically implemented by removing the short pipe 32 ′ on the inlet side, and the tooth claw according to claim 3 can be concretely realized by removing the short pipe 31 ′ on the outlet side. It can be implemented in a practical manner. Further, the short tubes 31 ', 32', 33 and the slide tube 35
By removing all of the above, the invention of claim 2 can be specifically implemented.

From the first state of the drainage basin shown in FIG. 12, the slide pipe 35 is slid to the left, for example, and pulled out from the short pipe 31 'on the inlet side.
It is divided into a tube integrating the 2 ′, the short tube 33, and the slide tube 35, and a short tube 31 ′ on the inlet side. From this state, the short pipe 31 ′ remaining in the first mouth portion 12 on the inlet side is removed, and the first mouth portion 12 on the inlet side is removed through the internal passage S of the cell body 1.
The invention of claim 2 can be specifically embodied by communicating with the mouth portion 17. In this case, whether or not to remove the tube integrating the short pipe 32 ′ on the outlet side, the short pipe 33, and the slide pipe 35 from the first port 13 on the outlet side is determined by the first port 12 on the inlet side. What is necessary is just to select suitably according to whether the water which flowed into the basin main body 1 reaches the pipe.

Further, from the first state shown in FIG.
When the tube 3 is pulled out from the tube 2 ', the tube 3 is divided into a short tube 31' on the inlet side, a short tube 33 integrated with the slide tube 35, and a short tube 32 'on the outlet side. Therefore, the tube integrating the short pipe 31 ′, the short pipe 33, and the slide pipe 35 on the inlet side is removed from the first port 12 on the inlet side, and the first port 12 on the inlet side is passed through the internal passage of the box body 1. By communicating with the second opening 17 via S, the invention of claim 2 can be specifically implemented.

Further, the work of sliding the slit pipe 35, removing the short pipe 33, and removing the short pipe 32 'on the outlet side is performed, and the short pipe 31' on the inlet side is left as it is. The third invention can be specifically implemented.

FIG. 13 shows an example in which the first state according to the second and third aspects of the present invention is formed using a drainage basin according to still another embodiment of the first aspect of the present invention. In this drainage basin, the pipe 3 is different from that in FIG. That is, the tube 13 is obtained by omitting the tube 33 at the center of the tube 3 described in FIG. Therefore, according to this drainage basin, the inventions of claims 2 and 3 can be specifically implemented according to the description of the drainage basin of FIG.

FIG. 14 shows a first state according to an embodiment of the present invention. The drainage basin used in this embodiment is the same as the basin body 1 described above.
And an expandable / contractible tube 3 disposed between the first ports 12 and 13 on the inlet side and the outlet side. That is, the pipe 3 has a short pipe 32 ″ connected to the first port 13 on the outlet side and a short pipe 31 ″ connected to the first port 12 on the inlet side. End of short tube 3
2 "is slidably fitted. Short tube 31"
Holds a sealing material 36 "such as an O-ring for water-tightly sealing the gap with the short pipe 31".

From the first state of the drainage basin shown in FIG. 14, the slide pipe 31 ″ and the short pipe 3
When the tube 31 "is pulled out from the first mouth portion 12 on the inlet side by relatively sliding the tube member 3" with the tube member 3 ", the first mouth portion 12 on the inlet side becomes the internal space of the box body 1. It communicates with the second port 17 via S to enter the second state. In this case, whether or not to remove the tube in which the tube 31 "and the tube 32" are integrated from the first opening 13 on the outlet side is determined by the first on the inlet side.
It may be appropriately selected depending on whether or not the water flowing into the basin body 1 from the mouth portion 12 reaches the tube, and the short tube 32 ″ with the short tube 31 ″ connected to the first mouth portion 13 on the outlet side. The same applies to whether or not to remove from the.

[0037]

According to the variable drainage basin according to the first aspect of the present invention and the method of switching the drainage basin according to the second to fourth aspects of the present invention, the drainage basin which is buried in the ground is provided. Since the direction of the flow path can be switched only by working in the internal space, it is necessary to change the direction of the pipeline when a new public sewer is installed in the area where the drainage pipe with the drainage basin was laid. There is no need to dig up the ground, remove existing drainage basins and pipes, or bury new drainage basins and pipes. It is not only useful for reducing the total construction cost, but also has an effect that the pipe laying can be performed in a short time with a simple operation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first state in a method of switching a drainage basin according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a state where an inlet pipe and an outlet pipe are connected to a first port in the method.

FIG. 3 is a cross-sectional view showing a state where a tube is cut in the same method.

FIG. 4 is a cross-sectional view showing a state in which the remaining portion of the tube is removed in the same method.

FIG. 5 is a sectional view of a second state in the method for switching the drainage basin according to the embodiment of the first invention.

FIG. 6 is a plan view illustrating switching of a flow channel in the same method.

FIG. 7 is a cross-sectional view of a second state in the method for switching a drainage basin according to the second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a main part in a state where a cap body is attached to the remaining pipe body remaining at the first opening on the outlet side.

FIG. 9 is a cross-sectional view of a main part showing a modified example of the first port on the outlet side.

FIG. 10 is a sectional view showing a drainage basin according to another embodiment of the present invention.

FIG. 11 is a cross-sectional view of a second state in the method for switching a drainage basin according to another embodiment of the third invention.

FIG. 12 is a sectional view of a drainage basin according to still another embodiment of the present invention.

FIG. 13 is a sectional view of a drainage basin according to still another embodiment of the present invention.

FIG. 14 is a sectional view of a first state in the method for switching the drainage basin according to the embodiment of the fourth invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Masu main body 3 Tube body 5 Cap body 12 1st opening part on the entrance side 13 1st opening part on the exit side 17 2nd opening part 31, 32 Remaining part of tube body S Internal space of the basin body

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E03F 5/02 E03F 5/10 E03F 3/06

Claims (4)

(57) [Claims] 1. A box body having a first opening on the inlet side and the outlet side communicating with the internal space at a middle part in the height direction, and a second opening communicating on the bottom part with the inner space, and the inlet side and the outlet side. And a separable pipe disposed between the first ports. 2. A method for switching the flow path of a drainage basin using a variable flow path type drainage basin according to claim 1, wherein pipes are arranged between the first port on the inlet side and the first port on the outlet side. From the first state in which the pipes are formed through the mouth and the ports are blocked from the second mouth by the pipes, after the pipes are divided at predetermined locations in the internal space of the box body, A second state in which the first port on the inlet side is communicated with the second port via the internal space of the box body by removing the remaining pipe body remaining on the first port on the inlet side. How to switch the drainage channel. 3. A method of switching a drainage basin using a variable drainage basin according to claim 1, wherein a pipe is provided between the first port on the inlet side and the first port on the outlet side. From the first state in which the pipes are formed through the mouth and the mouths are blocked from the second mouth by the pipes, after dividing a predetermined portion of the pipes in the internal space of the box body, The pipe remaining of the pipe remaining at the first port on the outlet side is removed, and the pipe remaining of the pipe remaining at the first port on the inlet is connected to the second port via the internal space of the box body. A method for switching the flow path of a drainage basin, characterized in that the drainage basin has two states. 4. A box body having a first opening on the inlet side and the outlet side communicating with the internal space at a middle part in the height direction, and a second opening communicating on the bottom part with the inner space, and the inlet side and the outlet side. A method of switching the flow path of a drainage basin using a drainage basin having an expandable / contractible pipe disposed between the first port portions, wherein the first port portion on an inlet side and an outlet side are provided. The pipes are arranged between them to form a pipe passing through their mouths, and from the first state in which the mouths are blocked from the second mouths by the pipes, the internal space of the box body is changed. In the second state, the pipe is contracted to remove the pipe from the first port on the inlet side, thereby connecting the first port on the inlet side to the second port via the internal space of the box body. A method for switching the flow path of a drainage basin, comprising: