Licensed plumbers must have license number ___________ and must be truthful.

Licensed plumbers are required to have their license number included on all advertising materials. This regulation is important for several reasons. Most notably, it serves to assure potential clients of the plumber's qualifications and credibility, as it allows them to verify the license status and any relevant details with the licensing board. By including the license number in advertisements, plumbers demonstrate professionalism and compliance with legal requirements, enhancing trust among consumers.

While having the license number displayed in company documents, posted at job sites, and on business cards can also be beneficial for identification and transparency, the specific requirement to include the license number in advertising helps promote an awareness of contractor legitimacy and protects consumers from unlicensed practitioners. Thus, emphasizing its presence in advertising captures the essence of consumer protection within the plumbing industry.