Answer 6: By pouring the hot water into the hose, the part of water molecule goes into the PVC hose.
This is called moisture absorption. The hose looks like white if the water molecule goes into the PVC resin hose due to the fact that a refraction angle changes. If the hose turns white, there is no functional problem. Also, as time passes by, moisture evaporates. As a result, hose returns to the normal color. For your information, in addition to PVC, polyurethane (PU) and nylon have higher levels of moisture absorption.