In response to recent heavy rainfall and resulting flood damage, the use of flood barriers has been increasingly adopted in Tokyo, supported by municipal subsidy programs aimed at encouraging flood prevention measures.
Last autumn’s torrential rains caused severe flooding across the Tokyo metropolitan area. On September 11, 2022, a stationary autumn rain front produced record-breaking hourly precipitation, with Setagaya Ward receiving 92 millimeters and Ota Ward 88.5 millimeters. In Shinagawa Ward, the Tachiai River overflowed, and urban runoff led to flooding that affected over 1,200 homes. Motokazu Wakaoji, 53, who operates a basement restaurant in the Togoshi-Ginza shopping street, recalled the floodwaters pouring down the stairs and submerging his establishment. The flood damaged kitchen equipment, including a dishwasher and refrigerator, and caused more than ¥2 million in losses, delaying the restaurant’s reopening until June.
Following this event, the Togoshi-Ginza shopping street association has encouraged local businesses to install flood barriers, with plans to purchase the panels in bulk by October. Tetsuro Kamei, 62, handling public relations for the association, noted that many businesses remain hesitant about adopting such measures but emphasized the importance of preparedness.
In January, a neighborhood association in Shinagawa Ward’s Hatanodai 2-chome district installed detachable aluminum flood barriers at its community hall, which hosts events including senior residents’ gatherings. The barriers, capable of withstanding water up to 50 centimeters high, cost approximately ¥1.4 million. The association received a ¥1 million subsidy from the ward’s flood prevention program. Shinagawa Ward’s subsidies cover 80% of the costs for individuals, up to ¥1 million, and 60% for corporations, up to ¥1.5 million. Applications for subsidies have increased markedly, rising from just a few per year through fiscal 2024 to 45 in fiscal 2025, and reaching 84 by early September of the current year.
Ota Ward, another area heavily affected by flooding last autumn—with 848 homes inundated—introduced a flood barrier subsidy program in December. The program has already received over 100 applications, reflecting growing awareness among residents, according to a ward official.
Beyond Shinagawa and Ota, four additional Tokyo wards—Setagaya, Edogawa, Nakano, and Nerima—have launched similar subsidy schemes this fiscal year. By the end of July, 20 wards and cities within Tokyo had implemented such programs. On a broader scale, the Tokyo metropolitan government began providing financial support for municipalities offering subsidies for flood barrier purchases starting in December.
Despite these initiatives, adoption in some areas remains limited, as residents and businesses still bear a portion of the expenses.
Demand for flood prevention and disaster preparedness products is also rising in commercial markets. LiveLight Co., a flood barrier supplier based in Nagoya, reported that sales in the Tokyo metropolitan area this year have approximately doubled compared to last year, with significant orders from commercial facilities and offices.
Other innovative products have entered the market, including Air Block, launched by Miyazaki-based One Step in September. The inflatable barrier, designed to be placed between walls, can be installed in as little as five minutes and is priced from ¥50,000 excluding tax. Additionally, water-absorbing bags like AquaBlock, produced by Hiroshima’s Nissui Chemical Industries Co., rapidly expand upon contact with water and are marketed as convenient, portable flood prevention tools.
With extreme rainfall events increasing, these flood barrier products and subsidy programs are playing a growing role in Tokyo’s efforts to mitigate flood damage and promote preparedness at both community and individual levels.