The Engineering and: Water Supply Department has let a contract to Adelaide and Wallaroo Fertilizers limited for the supply of an estimated 8,000 to 25,000'tonnes per annum of aluminium sulphate solution OW.5% A1203) to be used% ais'a coagulant for treating water'for Metropolitan Adelaide. Alumina hydrate, purchased from a Western Australian refinery will be used as a raw material for the manufacture of this 'filter alum'. There would be obvious advantages' in using a cheaper, local source of alumina and an earlier investigation (Goldney and Hayton, 1964) showed that a high-grade hydrated aluminium sulphate could be produced from clay from a large deposit at Birdwood, 30 miles' East of Adelaide. It was concluded that a production rate of about 10,000 tonnes per annum of filter alum (~16% A12 O3) would be necessary before the process envisaged would become economically viable. At that time, the demand in South Australia was only '500 tonnes annually with little prospect of significant increases. On the other hand, it is now clear that there will be a market for 10,000 tonnes per annum for water treatment in the near future. Moreover, since the specifications, for alum for water treatment,purposes are less stringent than for the paper industry, the process, could probably be simplified and the production costs reduced. For these reasons, the South Australian Department of Mines approved a project proposal for Amdel to re-examine the feasibility of producing the alum from Birdwood Clay, in the form of a concentrated aqueous solution. The specifications for the product were provided by Mr R. Stokes of the E & WS Department, and are included as Appendix A.