Most homes in Northern California have natural gas service. The provider is Pacific Gas & Electric (PG&E). What homeowners are responisble for is simple. That is, all property owners are responsible for installing and maintaining all piping after the PG&E meter. But here's an exception. Currently, PG&E is busy installing and uprgrading a large amount of their underground (UG) delivery mains. At times that will require moving the meter on your property for safety concerns. PG&E may dictate that your meter requires relocation. This will require repiping the part that you own, so it will route to the new meter locaiton. Here's the good news; when PG&E dictates a meter move, they pay for your piping to be re-routed. For that part PG&E will use and pay for a plumbing contractor to move your line. PG&E is concerned about the safety on their natural gas delivery system, and they're doing something about it.
How do I know if I have a natural gas leak? There a two ways to identify a leak. First, natural is a intenionally odorized gas. That is, you'll be able to recognize the leak by sense of smell. Second, the local provider, may suspect a leak and notify the customer.