A method and device is provided for tapping an existing primary pipeline (e.g., a water supply line) without cutting the existing primary pipeline. A secondary supply line may be installed by coupling the device to a valve of the existing pipeline. In various implementations, the device may have a single port serving as both an input (i.e., an inlet) and an output (i.e., an outlet). Among other advantages, the invention may be used to avoid costly procedures of cutting supply lines, to prevent water spillage, to integrate with existing alarm and home improvement systems, and to communicate wirelessly with utility companies for billing purposes.