Water standing in the meter box points to a leak on the service line, a leak at the meter connection, or plain groundwater and irrigation runoff. The first test is simple. Shut off every fixture, watch the meter dial, and if it still moves, water is leaving the system somewhere between the meter and the house. That stretch of pipe is the homeowner’s to repair, and the cost of replacing the water line from the meter to the house depends mostly on its length and depth.