All property shall be deemed capable of being served by a public sewer of the city, and service by such public sewer shall be deemed available if the first floor plumbing of any building or structure located thereon can be served by gravity into the city sewer lines, as provided in Sections 13.10.040 through 13.10.060, even though the basement drains of such building or structure cannot be served into the city sewers. (Ord. 947-04 § 2).