N.Y.C. Admin. Code § 27-2079: § 27-2079 Single room occupancy.

Every building containing rooming units, and each individual apartment used for single room occupancy, shall contain at least one water closet, washbasin and bath or shower for each six persons lawfully occupying rooming units therein, and for any remainder of less than six persons. At least one water closet shall be located on any floor containing a rooming unit. If there are not more than two rooms on the first story above the basement in a rooming house, no water closet is required on such floor but the occupants of the room shall be counted in determining the required number of facilities.