The steam pump house is a rectangular shed constructed of rendered blockwork walls.
A metal truss roof supports gabled corrugated iron roof. There are additional concrete walls on all but the western side (the building originally abutted a hillside on the west) built as blast barriers. The building houses a travelling crane gantry, boilers and two steam driven duplex pumps with connecting oil pipelines to pump oil to and from ships and onshore storage tanks. The pump house was constructed in 1927-28.
The construction of this oil fuel installation, together with the transfer of a Garrison to defend the installation, was the beginning of the major expansion of Darwin as a defence base. This military build-up was central to Darwin's development from a small outpost into a thriving city.