What is the most common type of work that a plumber does?

Installing waste and water lines.

Well are plumbers mostly installing new systems because we do a lot of new houses and new structure’s or offices we do a lot of additions so we normally need to connect to the existing water lines with the new area also when we doing the renovation we normally replace the existing water lines from galvanized to copper
Our Plummer’s sometimes need to do new sewer line but most of the time he’s connecting the existing one to the new area that we doing