Maryland Code, Labor and Employment § 5-606

(a) Upon installation of a sanitary sewer line in the State, each connection brought to the property line shall have a combination type fitting, capped at the horizontal end, with a vertical pipe capped within 4 feet of the surface.

(b) Each sewer house connection shall be designed to optimize safety, economy, functional efficiency, and operational maintenance.

(c) Vertical pipes to be used for house connections or cleanout pipes shall be a minimum of 4 inches in diameter.

(d) The requirements of this section apply in each county and subdivision in the State for any new installation or major modification occurring on or after January 1, 1992.