I'm not clear as to your question. You are responsible for the main water line from the back of the meter inbound to your home. If they damaged it through negligence or intentionally when they changed the meter, you can make a claim against them for the cost to repair. More likely, however, is that due to its age (assuming they are old), it did develop a leak as a result of the meter being changed - but that's not necessarily their fault. If your plumbing is old and in the course of their regular maintenance of the water system (replacing the meter) it developed a leak, that's probably on you. It will be hard to prove, absent some overt evidence that they installed the meter negligently, that they are at fault. Call your own plumber and get his opinion of what happened.

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