On 28 May 2025, the Japan Association for the 2025 World Exposition received an inspection report from the Venue Hygiene Monitoring Centre that Legionella bacteria concentrations in the Forest of Tranquility water basins exceeded the standard values set out in the “Guidelines for the Prevention of Legionnaires Disease” issued by the Ministry of Health, Labour and Welfare. In response, the water basins were drained and have been out of use since the morning of 30 May.
On 7 June, the water basin facilities on the west and south sides were cleaned and disinfected, filled with water, and tested for Legionella bacteria using the culture method. The test results were below the detection limit.
The decision to reopen the water basins on the west and south sides of the Forest of Tranquility will be made after coordinating with the Osaka City Public Health Centre regarding routine maintenance and regular water quality testing methods. The reopening will be announced at a later date.
The water basin on the east side is on the same water circulation system as the central pond in the Forest of Tranquillity. Taking into consideration the impact on the organisms inhabiting the central pond, we have decided not to clean and disinfect the east water basic, and it will remain closed for the remainder of the Expo period.
(Facility Maintenance and Management Bureau)
