Turn off all faucets, appliances, etc. Listen for toilet leak. Use
"stethoscope"; big screwdriver pressed to ear on handle end, to toilet body
on other end.
Observe water meter; assuming the meter is moving, you might want to verify
that the meter isn't nuts. It's pretty hard to imagine how a meter could
move, in the absence of water current, but you can listen to the meter. Use
a broom handle that has no broomhead on it. Push one end of handle against
meter, and the other end against your ear. You should hear a click, click,
click. Some people can hear the water meter beating, while they sit in
their houses, when their sprinklers are running.
You might also try this stethoscope method at various locations on the
premises, by pressing against pipes. You might thus "vector" your way to
the proximity of the leak.
Commercial leak detection is available for fresh water (pressure) plumbing.
It senses sound. Appropriate for tiny leaks.
Do you guys flush the toilet a lot?
Take long showers?
Use clothes washer a lot?

"EggRaid" wrote

What are your suggestions as next steps? How do I test if the pipe from
the
main to the house is leaking? Should I call a pro, etc?

Thanks,

ER