Rhondda Hall, Castlemaine
When our family moved from Queensland to Boort in 1964 every WC where a septic tank had been added had a notice on the back of the door with the rules, one of which was “Do not flush for minor uses”.
I fear modern Australians will not want to follow that rule when the sewerage plant is full (or during droughts), so I will offer some other mad suggestions to overcome the problem.
Building regulations should specify how big the rain water tank must be for all houses: the bigger the roof (keeping your floor dry) the bigger the tank (keeping your run-off on your place).
We should all plant more trees that hold large amounts of water, where possible.
I live at the bottom of McKenzie Hill, and a lot more water runs down the hill on the highway than did 20 years ago.