Your garden hose may pour out 600 gallons or more in only a few hours. Remember, when you leave the hose unattended, thousands of gallons may be lost in a very short time. Toilets are notorious for hidden leaks, and may waste hundreds of gallons a day undetected.
Leaks occur when the flushing mechanism is out of adjustment or when parts are worn.
Most toilet leaks are at the overflow pipe or at the plunger ball. Sometimes the overflow valve is worn and will run like a leaky faucet and have to be replaced. Otherwise, call a plumber. Plunger-ball leaks are not as easy to spot. Drop a little food coloring into clear water in the tank and wait.