For a typical family, more water is used to flush the toilet than for any other indoor purpose. You can significantly reduce your water use and save money on utility bills by replacing toilets which were installed before 1994. You can save on water used for flushing, plus prevent potential silent leaks which cost money in unplanned water usage.
Each toilet you replace could save you up to $200 per year on your water bill, and you can receive a $30 rebate when you purchase a new WaterSense-labeled high-efficiency toilet. Seattle Public Utilities has info how how to save money on your water bills, including tips on getting water-saving showerheads and bathroom faucet nozzles.