You can define the path of a run using a combination of polylines and lines, and then convert these objects into a plumbing run. 
- Define the curve of the layout path with the AutoCAD®  or  command. 
 
- Select the polyline or line that you want to convert, right-click, and click Convert to 
Plumbing Line.  
- Do one of the following: 
- Press Enter or enter n (no) to leave the layout geometry in the drawing. 
 
- Enter y (yes) to erase the layout geometry from the drawing. 
 
  
- Specify values for the plumbing line on the Design tab of the Properties palette, including style, dimensions, system, etc. 
 
- Click Esc to save your changes and exit.