Aussie weather patterns are fairly predictable. Winter promises three or so months of torrential rain, and its a good opportunity to refill your tanks and shore up your water storage. However, your water tank probably hasnt had attention in a while, so during autumn, its a good idea to clean out your tank so the water that gets collected in winter is fresh uncontaminated, and potable. http://homereadersdigest.com/keeping-your-tank-clean-in-autumn/