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Flood-proof / Safety / Comfort Sewerage

Prepare againist Flooding

Securing stormwater inlet capability

Stormwater flows into sewer pipes through stormwater inlets

If garbage accumulates or items are placed on stormwater inlets or street gutters, stormwater cannot flow into the sewer pipes, and the risk of flooding increases.

Illustration:Be careful not to put garbage into or place any items on stormwater inlets.

Prepare Sandbags, Waterbags, and Water Sealing Plates, etc.

  • It is possible to protect against shallow flooding using sandbags, water bags, and water sealing plates, etc.

  •  You can prepare a simple water bag by using a large plastic bag. A simple water bag can be made stronger by using it together with a cardboard box.

Illustration:waterbags

  • There are cases that the municipality distributes sandbags,etc .
  • For details, please contact your municipality.

Photo:Installation example of sandbags

Please install rainwater infiltration facilities

Rain that falls on the roof flows into the sewer pips through the inlets on drain pipes

Infiltration facilities have holes in the side of these inlets and drain pipes to infiltrate the stormwater into the ground.

By installing stormwater infiltration facilities, it is possible to reduce flooding damage.

Illustration:Why are stormwater infiltration facilities necessary?

When installing stormwater infiltration facilities

Q. Is it possible to install a stormwater infiltration facility anywhere?

A. Although it can be installed in most areas in Tokyo,  there are some places where it cannot be installed as follows:

× Cliffs or steep slope areas

× Areas at risk of landslides

× Inlets and private sewers where sanitary sewage flows

Q. Are there any subsidies?

A. In the 9 wards of Minato, Shinagawa, Meguro, Ota, Setagaya, Suginami, Kita, Itabashi and Nerima, there is a subsidy system for stormwater infiltration facility installation cost (as of April 2018).

For details, please contact your ward office.

Photo:stormwater infitration inlet

Be Careful of Flooding Damage in a Semi-basement House!

To customers who live in a semi-basement house or are considering to do so

As stormwater is likely to flow from the road into the house, there is a danger of flooding.

Also, there is a risk that the door will not be able to be opened easily due to water pressure from water that has flowed in.

When there is a danger of flooding, do not enter the lower part of the partially underground house.

Prepare sandbags, water bags, and water stop plates to prevent flooding.

Due to the rise of the water level inside sewer pipelines during heavy rainfall, if there is a bath or toilet

at a lower level than the road surface, sewage may flow backwards.

Install a sanitary drainage pump tank, so that sewage does not flow backward.

To Designers and House Owners

Avoid building semi-basement houses or basements in areas where flooding damage has previously occurred to the extent possible.

When building a semi-basement house or basement, install a sanitary sewage drainage pump tank, etc. Also, make the entrance higher than the road surface.

What is "Semi-basement house" ?

It means the entrance of a house is located a liitle below ground level.

Illustration:Damage situation during heavy rain

During sunny weather, water used in the toilet or bath is drained to the sewer pipe by natural flow.

As stormwater is likely to flow from the road into the house, there is a danger of flooding.

Due to the pressure of water flowing in, the door becomes difficult to open, creating a dangerous situation.

If there is a toilet or bathroom at a lower level than the road surface, sewage may flow backward.

If sewage flows backwards, the toilet or bath may be ruined.

 Illustration:Measures against Heavy Rain

Prepare sandbags, water bags, and water stop plates to prevent flooding.

Some municipalities distribute sandbags. For details, please contact your municipality.

Install a sanitary sewage drainage pump tank, so that sewage does not flow backward.

* A sanitary  drainage pump tank is a drainage tank with a submersible pump for sanitary sewage, a drainage pipe, and a check valve

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