341.170.  Qualifications of applicants for master plumber's license. — 1.  Applicants for a master plumber's license shall be at least twenty-five years of age and shall have had three years or more experience as a licensed journeyman plumber theretofore licensed by any county or city operating under plumbing laws or regulations equal to the requirements of sections 341.090 to 341.220.  The applicant shall possess the ability to direct other persons in the installation of plumbing and drainage and shall be skilled in planning, designing and installing plumbing and drainage facilities and shall have a thorough knowledge of the accepted standards, principles and art of plumbing for the protection of the public health.

  2.  An applicant for a license as a journeyman plumber shall be at least twenty-one years of age and shall have had at least five years' experience as an apprentice under the direction and supervision of a master plumber licensed under the provisions of sections 341.090 to 341.220 or a master plumber licensed under the plumbing laws and regulations of any county or city operating under laws or regulations equal to the requirements of sections 341.090 to 341.220.  He shall have a practical knowledge of plumbing and shall be skilled in the art of installing plumbing and drainage facilities and shall have knowledge of the accepted standards and principles of plumbing and sewer or drainage facilities for the protection of the public health.

  3.  An applicant for a master drainlayer's license shall be at least twenty-five years of age and shall have had three years' or more experience as a licensed journeyman drainlayer theretofore licensed by any county or city operating under plumbing laws or regulations equal to the requirements of sections 341.090 to 341.220.  The applicant shall possess the ability to direct other persons in the installation of drains and sewers and shall be skilled in planning, designing and installing sewer and drain facilities and shall have a thorough practical knowledge of the accepted standards, principles and art of drainlaying for the protection of the public health.

  4.  An applicant for a journeyman drainlayer's license shall have worked at drainlaying under the supervision of a licensed master plumber or master drainlayer for a period of at least one year and shall possess a knowledge of drainlaying and the ability to lay drains and shall have a thorough understanding of sewer and drain installation and shall have the ability to install all types of sewers and drains conformable with standard engineering principles and specifications.

  5.  Any licensed master plumber or journeyman plumber desirous of engaging in the business of drainlaying shall secure a drainlayer's license and no master plumber or journeyman plumber shall engage in the business of drainlaying without first securing a drainlayer's license.