Vertical plastic pipe should be supported at intervals of:

Vertical plastic pipe should be supported at intervals of every story to ensure that the pipe is adequately secured and does not sag or shift due to its weight and the forces acting on it. Supporting the pipe at each story provides stable structural integrity, helps prevent movement that could lead to stress on joints and fittings, and conforms to building codes and best practices in plumbing installation. This type of support is crucial, particularly in multi-story buildings, where the height and potential weight of the pipe can lead to significant dynamics. By providing support at each story, the risk of damage to the pipeline system over time is minimized, and it maintains optimal flow and function of the plumbing system overall.