Md. Code, Pub. Util. § 12-129

(a) Subject to subsection (c) of this section, any new or replacement piping that is buried or installed for the purposes of connecting a building to a water supply system, a sewerage system, an underground storm drain system, or any other applicable device shall be buried or installed with a wire or an equivalent product or technology that makes the piping detectable or locatable. (b) Any wire used to comply with subsection (a) of this section shall: (1) be an insulated copper tracer wire that is suitable for direct burial and has an American wire gauge (AWG) of at least 10, or an equivalent product; (2) be installed: (i) in the same trench as the piping that connects the building to the water supply system or the sewerage system; (ii) within 12 inches of the piping that connects the building to the water supply system or the sewerage system; and (iii) with at least one end of the wire terminating above grade in a location that is accessible and resistant to physical damage, such as in a cleanout or next to an external wall of the building; and (3) run from within 5 feet of an external wall of the building to: (i) the point where the piping intersects with the water supply system or the sewerage system; or (ii) the point where the sewerage system disposes of or processes the sewage. (c) The requirement of subsection (a) of this section with regard to replacement piping connecting a building to a water supply system or a sewerage system: (1) applies only to a complete replacement of the piping; and (2) does not apply to a repair or a partial replacement of the piping.