Abstract
The water distribution pipelines managed by the Bureau of Waterworks of the Tokyo Metropolitan Government
are approximately 27,000 kilometers long, and upgrading all of the pipelines to earthquake-resistant joint pipes is
expected to take many years and require great expense. Therefore, it is necessary to implement the renewal of
pipelines in an effective and systematic manner from a medium-to long-term perspective. On the other hand, the
legal durable years of water pipelines is 40 years, but the results of past surveys have confirmed that there had
been many pipelines with durability of more than 40 years. In this study, we focused on the fact that the main cause
of deterioration is pitting corrosion, and attempted to analyze the prediction of deterioration of ductile iron pipes
based on the results of investigations of the pipe bodies and surrounding soil. The results of this analysis indicate
that ductile iron pipes have service life of 50 to 90 years, which exceed the legal service life.
