A powerful earthquake off northeastern Japan last week left up to around 70,000 households without access to water in the region, local authorities said, underlining the urgent need to increase the ratio of quake-resistant water pipes in the disaster-prone country.
Water disruption in Miyagi Prefecture, which impacted about 37,000 homes, was mostly caused by damage to two key water pipes in the region that were more than 40 years old, according to the prefecture. One of them was not quake-resistant, it said.
As of March 2021, 40.7% of major water pipes in Japan were considered resistant to massive quakes, and the Health, Labor and Welfare Ministry aims to raise the proportion to 60% by fiscal 2028.
In Miyagi and Fukushima prefectures, which were hit hard by the March 16 temblor, the percentage stood at 46.4% and 56.3%, respectively. Kanagawa Prefecture had the highest percentage at 72.8%, while Kochi Prefecture had the lowest at 23.8%.
Water pipe construction and maintenance projects are typically financed by water bills paid to local governments. "It might lead to a rise in bills if we try to make all our pipes quake-resistant at one stroke," a Miyagi Prefectural Government official said.
Masakatsu Miyajima, a professor of earthquake engineering at Kanazawa University, pointed to the importance of promoting understanding about increased cost burdens among residents.
"There is a wide gap between regions in the percentage of quake-resistant key water pipes, which is a risk factor for large-scale, long-term water disruption," Miyajima said.
"The profitability (of water business) is more severe in regional areas than in cities as their population has been shrinking more rapidly," he added.