Do you live in a suburb with hard water in a house built before 2010? If you do, odds are you have dealt with pinhole leaks in your copper water main.
The only way to prevent this is by replacing this stretch of water piping with PEX (plastic) piping.
Typically this can be done in one day with minimal disturbance to your house. Farr Plumbing specializes in coordinating with local cities & water departments if necessary.