Underground piping should be supported by what type of material?

Supporting underground piping with compacted soil or sand is essential for maintaining the stability and integrity of the pipeline. Compacted soil provides a solid foundation that can handle the weight and pressure exerted on the pipes, preventing movement or sagging over time. Sand is particularly effective because it can easily conform to the shape of the pipeline, providing even support and avoiding stress concentrations that may lead to damage.

In contrast, loose soil lacks the structural integrity needed to support piping adequately, leading to potential shifts that could cause misalignment or cracking in the pipes. Gravel might not provide the same level of compact support as properly compacted soil or sand since it can create gaps that allow for movement. Water, while it may appear to provide a medium for support, can erode soil and create instability, leading to potential damage to the piping system. Thus, compacted soil or sand is the most reliable option for supporting underground piping.