Plumber licenses are earned by persons having completed the required coursework and apprenticeship. Individual states have additional criteria aside from the traditional 4 to 5 years apprenticeship training. Each candidate for a plumbing license has to complete classroom coursework and hands on training while being supervised by a licensed journeyman or master plumber.

Different states have different levels of working plumber, but the majority of states have apprentice plumbers, journeyman plumbers and master plumbers, with apprentice having the lowest qualifications and master having the most, having passed advanced plumbing classes and usually owning their own businesses with journeyman plumbers and apprentices working for them.

Licenses are given by state according to each states code for plumbing. Individual state's have regulations pertaining to size of population and plumbing work, and local townships and cities may have their own criteria for obtaining a license to work as well as obtaining a license to be a plumber.