Rainwater tanks just make sense when it comes to saving money. What seems completely illogical to me is that households are still using drinking water to wash clothes and flush toilets. The NSW Government is offering a rebate of up to $1500 for the cost of the rainwater tank, saving you up to $140 bucks each year off your water bill.
This is a great offer and lasts only till 30 June 2011, get in and grab one while this offer is on the table. The minimum capacity eligible for this rebate is 2000 Litres, the average price for an above ground, slim tank of that capacity is about $840.00
The rebate is split between the cost of the tank, and the installation to your washing machine, and toilet.
To make the most of this i recommend installing a medium sized tank, or 4,000-6,999 litre capacities, as you'll take home more towards the cost of the tank and save the most because you'll have more rainwater available to you on demand.
For a full list of rebate amounts on offer per capacity, see the table listed on the sydney water website