Centennial Park Reservoir, Underground water reservoir in Centennial Park, Australia

Centennial Park Reservoir is a covered water storage facility buried beneath the ground in Sydney's eastern suburbs, constructed with brick walls and a curved arch ceiling. The structure sits under layers of earth and turf that form part of the park above.

It was built between 1896 and 1898 by the NSW Public Works Department and ranks among Australia's largest covered water storage works from that era. The structure was created to supply water to Sydney's rapidly expanding eastern suburbs during the late 1800s.

The reservoir's site lies within the former Sydney Common, proclaimed by Governor Macquarie on 5 October 1811, and in Gadi clan territory between Darling Harbour and South Head. A map engraved by J. Walker in 1791 or 1793 marked a Kangaroo Ground near here, kept open by regular Gadi firing to attract game. The name Centennial Park comes from the parkland laid out in the 1880s.

You can view the reservoir site from ground level in Centennial Park, where an iron fence marks its boundary. The location is easy to reach on foot and the park offers walking paths throughout the grounds for exploring the wider area.

The reservoir site is enclosed by a wire fence, not a cast-iron one, and the enclosed area is accessible: in November 2022 a few people were walking dogs there and a playing field was marked out on part of it. A sign on a building reads "Centennial Park Reservoir WS0023".