TOKYO (AP) — Osaka has received a hefty gift of gold bars worth 560 million yen ($3.6 million) from an anonymous donor asking for its specific use: to fix the Japanese city’s dilapidated water pipes.

The gold bars weighing 21 kilograms (46 pounds) in total were given to the Osaka City Waterworks Bureau in November by the donor who wants to help improve aging water pipes, Mayor Hideyuki Yokoyama told reporters Thursday.

“It’s a staggering amount and I was speechless,” Yokoyama said. “Tackling aging water pipes requires a huge investment, and I cannot thank enough for the donation.”

The mayor said his city will respect the donor’s wishes and use the gift to improve waterworks projects.

Concern over the safety of Osaka’s waterworks systems grew after a massive sinkhole swallowed a truck and killed the driver last year. It was linked to a damaged sewer in Saitama, north of Tokyo. Osaka had 92 cases of water pipe leaks under city roads in the fiscal year ending March 2025, the city’s waterworks official Eiji Kotani told The Associated Press on Friday.

With the population of 2.8 million, Osaka is the country’s third-largest city that serves as a western Japanese capital.

Most of Japan’s main public infrastructure was built during the rapid postwar economic growth.

Urban development in Osaka, a regional commercial hub, started earlier than many other cities and its water pipes and other infrastructure are also aging earlier, Kotani said.

Osaka needs to renew a total of 259 kilometers (160 miles) of water pipes, he said. Renewing a 2-kilometer (1.2 mile) segment of water pipes would cost about 500 million yen ($3.2 million), Kotani said.