If the leak isn't at the meter or the foundation... it's usually a huge waste of time to chase a leak. Even if there's a wet spot in the yard, there's no guarantees it's within 20' of the wetness.
Turn off the water at the main cutoff in the house. Check the meter dial for movement. If moving...
Can I come make holsters for a few hours a month... in exchange for product? Have a couple idea kicking around in the head... and not the means to produce them! :p