大阪の上水道供給問題-府・市レベルの上水道供給構造と水道管老朽化-大阪の上水道供給問題-府・市レベルの上水道供給構造と水道管老朽化-AA11337282 Issues with Drinking Water Supplies in Osaka : The Supply Structure of Drinking Water and Dilapidated Water Pipes at the Prefectural and City Levels
Data on Japan clearly show that it lags behind in addressing the decrepit condition of municipal drinking water facilities and improving earthquake resistance of many structures. However, it is hard to understand the seriousness of each utility's path-dependent issues and their countermeasures from a simple statistic such as nationwide average. Thus, this paper investigates the situation of dilapidating water pipes and possible measures to diminish their effects. In this study, I focus on the supply structure of drinking water suppliers in Osaka City, Sakai City and Izumi City, as well as neighboring cities, as well as Osaka Prefecture. Results show that Osaka City, the only water supplier in Osaka Prefecture that gets 100% of its water from its own water resource, owns a critically high share of old pipes (those over 40 legal durable years), in total pipes and in length. The city's share is higher than both the nationwide and Kinki region-wide averages, and raises the prefectural average for Osaka. In contrast, the shares of old pipes of other water suppliers such as Sakai City are not high on average. However, since they rely on Osaka Prefecture's bulk water supplier for their water, whose share of old pipes is even higher than that of Osaka City, the situation could actually be worse than seen from the numbers. For example, Izumi City, which is still absolutely free of old pipes, purchases its water from Osaka Prefecture and the Senboku Water Supply Authority, whose water pipes can also be classified as old. Therefore, problems regarding the water supply of neighboring suppliers within a single region differ in their seriousness and possible policies to address them. Such a peculiarly complex situation stems from an overabundance of small-scale utilities created by the traditional Japanese regulatory regime for drinking water supplies.