With water too precious to waste ...Don't forget to check your water meter outside your house every once and a while. Makes sure the dishwasher or ice maker isn't running or anyone using water at the time.
Even the tiniest leak will show water usage (ours has a tiny little red triangle that moves back and forth). I heard that familiar leaking sound and turned off the water supply at the toilet and off to Lowes for a new fill valve. A little patience is all that is needed to get the job done and a few tools too.