Use AWWA's online tool to estimate water waste and learn how much water you could be saving.
For smaller/slower leaks - count the number of drips in one minute from the leaky fixture. Note: 5 drips per second amounts to a steady stream.
Fast Running Faucets
For larger/more rapid leaks - hold an 8 ounce cup under the dripping fixture and time, in seconds, how long it takes to fill the cup.