Mulgrave Tank was located on the 400 metre timber viaduct spanning South Creek between Mulgrave and Windsor Railway Stations. The viaduct was first constructed with the opening of the Blacktown to Richmond line in 1864 then upgraded to take heavier rolling stock in 1876. The viaduct featured a water tank to provide water for the steam locomotives hauling the trains along the line. A steam driven pump was used to fill the tank mounted next to the track directly above South Creek.
A photograph of the viaduct and the Mulgrave Tank is part of the collection of the Australian Railway Historical Rescource Centre Collection. Information and photographs about the railway line are mounted in interpretational signage at various locations at Windsor Railway Station.
30 November 1864
Report published in the Sydney Morning Herald on completeion of the branch line from Blacktown to Richmond in 1864 included the South Creek viaduct:
The viaduct across South Creek [at Mr Cunneen's] is a very substantial structure; it is twelve chains in length, and has an opening over the main creek ninety feet in the clear, spanned by a laminated arch. After crossing South Creek, the line passes close by the extensive farm buildings and boiling-down establishment of Mr. R. Fitzgerald, and enters the town of Windsor immediately at the back of the old Government poor-house, the station being on the property of the late Mr. Cope, facing the main street of Windsor, and adjoining the Presbyterian burial-ground.