plumber
A tradesperson who installs and repairs pipes and plumbing fixtures.
配管工を呼んで、水漏れを直してもらった。
I called a plumber and had the leak fixed.
水道屋 is a more casual term for a plumber or waterworks repair person, while 配管工 is a formal occupational title.
Compound of 配管 (plumbing, piping) and 工 (worker, craftsman).