To echo the "World Environment Day" established by the United Nations, Green Council designates 5 June as "Hong Kong Green Day" every year, with an array of activities promoting eco-friendly lifestyle. Themed as "Wave of Change for a Sustainable Hong Kong", the kick-off ceremony of "Hong Kong Green Day 2025" was held at Olympian City 2 on 5 June 2025.
As a supporting organisation, WSD arranged a game booth onsite sharing water conservation messages and the history of Dongjiang water supply to Hong Kong, complemented with a meet-and-greet of the WSD mascot, Water Save Dave, motivating visitors to save water.