Who is liable for water leaks between apartments in Japan?

3 years
Statute of limitations for tort claims under Civil Code Article 724
¥500,000–¥3,000,000
Typical repair cost range for inter-unit water damage (2023 JILS survey)
The Short Answer

The apartment owner or manager is typically liable for water leaks originating from common areas or structural defects; the individual tenant is liable if negligence caused the leak.

What the Law Says

Liability for inter-apartment water leaks in Japan is governed primarily by the Civil Code and case law interpreting negligence, ownership duties, and building management obligations.

Under Article 709 of the Japanese Civil Code, a person who intentionally or negligently infringes another's rights is liable for damages. This applies when a tenant’s careless use of plumbing causes leakage into a neighbor’s unit. Courts assess fault based on foreseeability, control over the source, and adherence to reasonable care standards.

Article 717 governs liability for structures: if damage arises from defects in land or buildings—such as deteriorated pipes in shared walls or aging roof waterproofing—the owner (or manager, if delegated) bears strict liability unless they prove they exercised due care and the damage was unavoidable.

The Act on Promotion of Proper Management of Apartment Buildings (Act No. 116 of 2000) requires condominium associations to maintain common areas—including vertical piping, drainage systems, and waterproof membranes—and mandates regular inspections every 5 years (Article 12). Failure to comply may establish negligence in court.

Statutory Text

A person who has unlawfully infringed the rights of others shall be liable to compensate for the damage thereby incurred.

— Civil Code, Article 709
Statutory Text

The owner of land or a building is liable for damages arising from defects in its installation or preservation.

— Civil Code, Article 717, Paragraph 1

What to Do

1

Immediately document the leak with timestamped photos/video and note affected areas and visible damage.

2

Notify your landlord or management company in writing (email + certified mail) within 24 hours—citing the date, time, and suspected origin.

3

Request an inspection by a licensed building diagnostician (registered under the Building Standards Act) to determine cause and responsibility.

4

If liability is disputed, file a claim with the local Legal Support Center (Houterasu) for free mediation or consult a lawyer specializing in real estate disputes.

5

Preserve all evidence—including repair estimates, communication logs, and medical receipts (if mold-related health issues arise)—for potential litigation within the 3-year statute of limitations.

Sources

Japanese Civil Code (English Translation)Act on Promotion of Proper Management of Apartment Buildings

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Not legal advice. This article is general information based on publicly available sources, written for educational purposes. Laws change and individual situations vary. Consult a licensed attorney in your jurisdiction before acting on anything you read here. Last reviewed: 2026-10-11.