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Regarding accidents involving PVC-U water supply pipes, specialized statistics were compiled in North America, showing that over 80% of such accidents were caused by improper construction methods. The common situations are as follows: 1. The trenches and backfill soil do not meet the specified requirements. This situation is often seen in mountainous areas, where there are many stones in certain areas; the trenches are dug manually or by blasting, resulting in a highly uneven bottom covered with sharp stones. In such cases, according to relevant regulations, the stones at the bottom of the trench should be removed and at least 15 centimeters of sand should be laid down before the pipes can be installed. However, some workers are irresponsible or cut corners by not laying any sand or only laying a minimal amount of it, and then directly lay the pipes on top of the stones. A common issue with inadequate backfilling is the use of larger bricks, tiles, or stones as backfill material, which are simply thrown onto the pipes ； Second, after backfilling, compaction is not carried out in accordance with the provisions of the \"Technical Code for Buried Rigid Polyvinyl Chloride Water Supply Pipes\". 2. The construction of cement thrust blocks at joints such as tees, elbows, and reducers does not meet the requirements. According to the \"Technical Specifications for Buried Rigid Polyvinyl Chloride Water Supply Pipelines\", thrust blocks should be installed at joints of pipes with a diameter of φ≥110mm, such as tees, elbows, and reducers, in order to prevent the pipes from shifting. The concrete used for these thrust blocks should have a strength of at least C15, and they should be poured on-site on the original soil foundation and the slopes of the trenches. Some contractors do not pay sufficient attention to the role played by thrust piles. They use wooden stakes or iron wedges placed next to the pipes as substitutes for thrust piles. Sometimes, the concrete piles are too small or not poured on solid soil, and in some cases the strength of these thrust piles is insufficient. As a result, during pipe operation, these thrust piles fail to perform their function and become ineffective, leading to misalignment and damage of pipe fittings such as tees and elbows. 3. No automatic exhaust valve is installed, or it is installed in an inappropriate location. During water transmission, gas in the pipes escapes and accumulates in the raised areas of the pipes, which can even lead to air blocks. When the flow rate of water in the pipes changes, the air bubbles formed in these raised areas keep expanding and contracting. The pressure generated by compressed gas is dozens or even hundreds of times greater than that generated by compressed water. In such cases, these problematic pipes may cause the following issues: (1) Water flows upward along the pipe, but no water emerges at the downstream end, as the air bubbles inside the pipe block the flow of water, resulting in separation of the water column. ⑵The compressed gas inside the pipe, when compressed to its maximum limit, expands rapidly, causing the pipe to rupture. ⑶When water from a source at a higher elevation is conveyed downstream at a certain speed through gravity flow, if the valve upstream is closed suddenly, the water column upstream in the pipe does not stop immediately due to the difference in height and the inertia of the flow; it continues to move downstream at that same speed. At this point, a vacuum is created in the pipe as no air can enter in time, resulting in the pipe being collapsed and damaged by negative pressure.