160PE pipe flattened

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The outlet pipe of the centrifugal pump is made of 160PE material. The pipe runs from the ground up to the cable tray, at a height of about 4–5 meters and a length of around 30 meters; from there it continues for another approximately 200 meters before reaching the water tank. There are at least 4–5 bends in this pipeline. When testing the water in the underground tank, the flow was normal. Later, a float-level control system was installed to automatically start the pump for pumping water. Suddenly, it was found that the pipe on the cable tray had been flattened; the vertical section of the pipe within the bent part of the cable tray, about 1 meter long, also became distorted and flattened, though not to the same extent as that on the cable tray. The analysis is as follows: For a pipe to be flattened by suction, there must be a vacuum condition inside the pipe. It can therefore be inferred that there must be a significant amount of water stored in the pipe leading from the tray to the ground level. On the other hand, the level of water indicated by the float is likely very low; as soon as the pump starts working, it draws all the water out and the pump stops. At this point, the water that has just been poured into the tray loses its pressure and flows back toward the ground, creating a vacuum effect. The water on the ground surface is drawn toward the tray due to this vacuum force. By the time the water reaches the height of the tray, the water that flowed back earlier has already reached the ground level, preventing further water from rising up the pipe. At this stage, the vacuum force is at its maximum, but since the pipe on the tray is empty, it gets flattened. Please share your thoughts – is my analysis correct?