No drain or sewer pipe shall be less than four inches internal diameter, and all drains and sewer must be of a size adequate for its purpose and such as shall convey and allow freely and entirely to pass whatever enters, or shall enter the same. If a four-inch pipe is used, it shall be laid to a grade of not less than 2%.
(Prior Code, § 4.04.120) (Ord. 160, passed - -; Ord. 252, passed - -; Ord. 254, passed - -)