Horizontal PVC and ABS pipe shall be supported at intervals not to exceed ______ feet.

Horizontal PVC and ABS pipes must be supported at intervals that do not exceed 4 feet to maintain system integrity and prevent sagging or displacement. This support requirement is crucial because it helps prevent undue stress on the joints and connections of the pipes, which can lead to leaks or failures over time. Proper support also ensures that the pipes remain properly aligned and reduces the risk of damage from impacts or other external forces. The National Plumbing Code and local building codes generally mandate this interval to ensure that plumbing installations are safe and durable. Maintaining these support intervals contributes significantly to the overall performance and longevity of plumbing systems.