Candidates for licensure must: Be at least 18 years of age. Pass the exam administered by the Commission. Either: Complete 4 years in an apprenticeship program approved by the Commission, OR Present evidence acceptable to the Commission of 4 years experience in the trade, OR Have 4 years work experience under the direction of a licensed plumber. Pay all application and examination fees. Have not been convicted of a crime nor have been subject to disciplinary action that would interfere with the ability to carry out professional duties. Apprenticeships and other non-licensed plumbing jobs have differing requirements. More detailed information may be obtained directly from the Indiana Plumbing Commission.