The infrastructure ministry announced its findings on Tuesday. Inspectors examined a total of 4,692 kilometers of sewer pipes by the end of February. Some 748 kilometers require immediate countermeasures, representing about 16 percent of the inspected total. Consequently, the ministry will ask 383 municipalities to take urgent action. These local governments must perform repairs without delay.
A deadly sinkhole accident in Yashio city triggered this survey. The incident occurred on January 28, 2025 in Saitama Prefecture. A huge sinkhole opened up on a road intersection, and a passing truck fell into the hole. The 74 year old male driver tragically lost his life. Rescue workers recovered his body about three months later. Corrosion of a sewer pipe caused the ground to collapse, highlighting a serious sewer pipe risk across aging infrastructure.
In March last year, the ministry requested local governments to inspect aging pipes. The survey targeted pipes with diameters of 2 meters or more. It also covered pipes in use for 30 years or longer. Inspectors looked for corrosion, sagging and cracks along these routes. The total length under inspection reached approximately 5,332 kilometers.
The survey divided findings into two emergency levels. Emergency level I requires action within one year. Some 201 kilometers in 46 prefectures fell into this category, while only Yamanashi had no level I pipes. Emergency level II requires full repairs within five years after temporary measures. Some 547 kilometers across all 47 prefectures received this classification.
The ministry will now provide technical and financial support to local governments. Officials will also review inspection standards and check frequencies. The ministry will call on local governments to complete assessments of the remaining pipes. Many sewer pipes still need inspection, and the Yashio tragedy demonstrated the deadly consequences of neglect. Local governments must prioritize these repairs despite budget constraints. Ultimately, regular inspections are essential for public safety. Comprehensive pipe assessments will continue over the coming months to mitigate the sewer pipe risk.
