Hiring the wrong plumber in Tempe, Mesa, or Chandler can turn a minor repair into a major expense. This guide walks East Valley homeowners through the exact steps to vet a plumber before work starts – verifying their Arizona ROC license, confirming insurance, getting written estimates, and understanding when permits are required. Arizona’s hard water and extreme heat create unique plumbing stress that makes local knowledge matter. A clear checklist, a comparison of licensed versus unlicensed contractors, and answers to the most common hiring questions help homeowners make confident, informed decisions in 2025.