The subgroup has been working for a few weeks now and we have resolved that rainwater tanks is deemed a structure under the Australian Building Codes. Regulations state that all rainwater tanks in Wind Category 3 require a tie down system.
Building Regulation 2006, schedule 1, section 13. If the rain water tank is within Wind Region C (tropical cyclone area) mentioned in AS1170.2 Wind Loading Code it will need to comply with the tie down requirements of a class 10 structure.
The group can now proceed to compile an example of the forms needed to be completed, an example site plan and details of the fees.