Faucets - Check all faucets and piping for leaks by monitoring for drips of water under sinks and from exposed pipes. Perform an inspection with the water on and off, as some leaks only occur when the water is on.
Toilets - Add a few drops of dark food coloring in the back of the toilet tank. Do not flush the toilet. Wait for a few minutes. If the food coloring appears in the toilet bowl, this means you have a leak. Some toilet leaks are intermittent, so you don't always see or hear the water running.
Pipes - Check plumbing in the basement by monitoring for drips of water coming from exposed pipes.
Meter - Turn off all water using appliances and water fixtures inside and outside your home. Check your meter to see if the leak detector (small black or red triangle) is spinning or slightly vibrating. If it is, then you most likely have a leak and should try to investigate further.