The Millbrook Reservoir was constructed between January 1914 and 1918 and when completed doubled Adelaide's water storage. The reservoir controlled the flows of the upper reaches of the River Torrens between Gumeracha and Kersbrook. Central to the construction were a conduit 770 feet in length to a supply weir and then a mile long inlet tunnel to the reservoir drilled through solid rock by workmen and machines. The project was completed in July 1918. The puddle trench was dug out of rock before being carefully lined with clay to ensure water could not leak from the reservoir embankment.