Based on the level of respect or formality, you can say "I am a plumber." in Korean in 3 ways:

• Informal: na-neun baegwangong-iya. (나는 배관공이야.)
• Formal: na-neun baegwangong-iyeyo. (나는 배관공이예요.)
• Very formal: jeo-neun baegwangong-imnida. (저는 배관공입니다.)