Can You Check Flood Risk Before You Rent? Hazard Maps and Disclosure in Japan

At 6:20 a.m. on 27 August 2026, the Japan Meteorological Agency issued emergency heavy rain warnings for Hakui City, Shika Town, Hodatsushimizu Town and Nakanoto Town in Ishikawa Prefecture, and for Himi City in Toyama Prefecture. Our thoughts are with everyone affected. Linear rainbands formed repeatedly around the Noto Peninsula, and six-hour rainfall reached 211.0 mm in Himi and 210.0 mm in Hakui by 6:20 a.m. The agency urged residents to secure their safety immediately and warned of road flooding, inundation in low-lying areas, river overflow and landslides.

After a flood, people often note that the places most likely to be hit were known in advance. Chiba Nippo compiled figures from the Ministry of Land, Infrastructure, Transport and Tourism's Chiba and Metropolitan road offices, the prefecture and 20 municipalities: during the heavy rain of 13 to 14 August, at least 45 of the 95 designated risk points such as underpasses were flooded. The 14 municipalities under emergency warnings contained 66 of those points, and 41 of them flooded. In Chiba City, which recorded 351 mm on 13 August, 15 of 16 municipal and national road locations flooded. In other words, more than 90% of the flooding happened at spots already identified as risk points.

For renters, this is actionable. Unlike buying, renting gives you more freedom to move, which makes the thirty minutes you spend checking before signing all the more valuable. This article sets out how far you can investigate flood risk when renting in Japan, through three entry points: hazard maps, the statutory disclosure, and insurance. For decisions specific to your situation, please consult a licensed real estate transaction specialist or insurance agent.

How far can you check flood risk before you rent?

In Japan, projected inundation from river flooding, inland water, storm surge and tsunami, along with designated landslide warning zones, is published by the authorities in map form. The Ministry of Land, Infrastructure, Transport and Tourism's Hazard Map Portal (https://disaportal.gsi.go.jp/) offers an overlay map that layers several hazards on a single view, plus links to maps produced by each municipality. Enter an address and you can check it before you even book a viewing.

Do not stop at whether the area is coloured in. Check which depth band the projected inundation falls into. Less than 0.5 metres and more than 3 metres mean entirely different things for a ground-floor flat. Note also that river flooding and inland water, where rainfall exceeds the drainage capacity of sewers, are usually shown on separate maps, so a property far from any river can still sit inside an inland water projection.

Finding something on the map does not mean the only answer is to rule the property out. Within the same area, risk varies with the floor level, the height above the road, where the parking is, and which floor holds the electrical equipment. Treat the map as a tool for narrowing down what to inspect during a viewing rather than a filter for discarding listings.

Is the flood hazard map covered in the statutory disclosure?

Leases arranged through a licensed broker require a disclosure of important matters, delivered by a registered real estate transaction specialist before the contract is concluded. An August 2020 amendment to the enforcement regulations of the Real Estate Brokerage Act added the approximate location of the property on the municipality's flood hazard map to the list of matters to be explained. Where a property sits inside a landslide warning zone or a tsunami disaster warning zone, that must also be disclosed.

What matters here is that the disclosure covers location, not a verdict on safety. Being told that the property falls in a given part of the hazard map means neither that it is dangerous nor that it is safe. You still need to weigh the depth band, the distance to an evacuation site, and what the building itself does about the risk.

Where a municipality has not produced a flood hazard map, the disclosure will say so. No disclosure does not mean no risk. In that case, it is worth checking the prefecture's projected inundation maps and any record of past flooding yourself.

What should you look at when renting on the ground floor or below?

Within one building, the burden of a flood differs sharply by floor. Ground-floor, semi-basement and basement units can take water into the living space even where projected depth is shallow. During a viewing, look at the height from the road to the entrance, the slope of the ground in common areas, and whether the layout channels rainwater toward the building.

The equipment outside the unit is easy to overlook. Where the electrical substation or the lift machine room sits in the basement or on the ground floor, flooding can turn into a prolonged power or lift outage. Residents on upper floors feel that too. A semi-basement car park raises a separate question about damage to vehicles.

You cannot check everything during one viewing, so put your questions to the management company and ask for answers in writing, by email if possible. Whether the building has flooded before, and how long recovery took, are questions worth asking.

If the unit floods, what happens to rent and repairs?

Where a rented property is damaged, repairs to the building itself are in principle the landlord's responsibility. Under the Civil Code, the lessor bears the duty to carry out repairs necessary for use of the leased property, except where the damage is attributable to the tenant. The contents insurance a tenant holds covers their own furniture and appliances, not the building.

Where part of the unit becomes unusable, the Civil Code provides that rent is reduced in proportion to that part. In practice, disputes tend to turn on how much of the property was unusable and for how long, so photographs taken immediately after the event, records of exchanges with the management company, and the repair schedule all matter.

If the building is lost entirely and the property can no longer be used, the lease terminates. Settling the deposit and finding somewhere else to live then become the immediate issues. Local authorities often set up temporary housing and advice desks after a disaster, so check the official information for the affected area.

In the SUMIMOTO Hub app, a 24-hour AI adviser explains how to read a disclosure document and how to interpret the scope of your insurance cover, in several languages. Working out what to check before a viewing lets you spend the limited time on the things that matter. For final decisions on contract terms or cover, please consult a licensed real estate transaction specialist or insurance agent.