The Hope Valley Reservoir is a 2,840 megalitres (100×10^6 cu ft) service reservoir in Hope Valley, South Australia, a suburb of Adelaide, South Australia.

[1] When completed in 1873 it was the second reservoir constructed in Adelaide; it is the oldest still in use in South Australia.

[2] It covers 52 hectares (128 acres) and is retained behind a 950-metre (3,117 ft) long clay-cored earth wall.

The river is also used to transfer water from the Kangaroo Creek and Millbrook reservoirs.

[1] In December 2020, the reservoir was opened to the public for the first time for activities including walking, running, cycling and picnicking.