Is Saving Water Destroying Water Pipes in Japan?

Japanese daily water usage per capita was 169 liters per day in 1965, but almost doubled in 30 years and grew to 322 liters in 1995. During times of high economic growth, flush toilets, electric washing machines, and bath units with showers spread to common households, and the lavish use of water became characteristic of a lifestyle of abundance.

However, prompted in part by large-scale droughts primarily in western Japan in 1994 and 1995, people gradually started saving water. Products like washing machines, warm-water bidet toilet seats, and flush toilets began competing for water-conservation conscious consumers with water-saving functions, and daily per capita water usage fell as low as 284 liters by 2015.

This decrease shows that water has been used increasingly sparingly, posing a challenge to water utilities whose falling revenues could lead them to bankruptcy. In Japan, whose population is shrinking each year, total water usage is projected to continue to decrease in the years ahead.

Additionally, water pipes that were developed during a period of high economic growth have now gone beyond their service life of 40 years, and it is past the time to rebuild them. The problem, however, is that the utilities whose businesses have deteriorated due to decreased demand cannot afford the refurbishment costs, and increasing numbers of pipes past their service life are still being used. The ratio of water pipes in use that are over 40 years old reached 14.8% in 2016, but the renewal rate of water pipes remains at a lower, flatter rate. At this rate of renewal, it is estimated that it will take 130 years to update all the pipes in the nation’s network as it stands today.

During the northern Osaka earthquake on June 18, 2018, water pipe damage and ruptures caused leaks and outages affecting over 200,000 people in Osaka, Takatsuki, Suita, and other cities. The Osaka prefectural water pipe aging rate is 28.3% as of 2015, the worst nationwide and almost twice the national average.

The probability that an earthquake of a seismic intensity of 6 or higher will occur within the next 30 years is high on the Pacific coast of Honshū, home to the heavily populated Tokyo, Tōkai, and Kansai areas. The upgrading of water pipes, which is extremely important for urban infrastructure, is a major issue for Japan as a whole.