The WT tank wagons were vehicles used for carrying water.
For rail use there were two types of liquid carriers: 'Tanks' and 'Trucks'. The only difference the author has been able to figure out is that 'Trucks' were used to carry bulk water for locomotives, firefighting etc., and 'Tanks' were used to carry water that could not be contaminated, such as drinking water.
During times of drought, WT's had been used for 'Domestic Water' use and were suitably lettered.
The WT group was numbered 1 - 236.
Numbers 1 to 180 were built 1902 - 1910. Numbers 181 onwards were converted from steam engine tenders and miscellaneous tank wagons.
To provide for water in times of drought, the railways built sixty tank bodies of the same style as numbers 1 to 180. These tanks were stored at each of the Workshops: Newport, Ballarat, Bendigo. When required for traffic they were fitted to standard _I__ / _IA_ / _IZ_ open wagons. When the drought was over the tanks were removed and the wagons returned to normal service.
Another expedient method was also used up to the 1950's.cartage was used. Four wheel open wagons were lined with canvas tarpaulins and the wagons filled with water, presumably from steam loco water stand pipes. As train movement was likely to induce surging, the author presumes the trains were run on short 'out and back' trips with wagons only loaded about halfway up the sides.
At various times, tanks have been temporarily converted for other other traffic.