The red line of PPR pipe means hot water and the blue line means cold water, but the owner of the second-hand house I bought last year left a wireless PPR pipe to ask what this means.

There may be defects, but the price is very cheap. At present, the materials used for cold water and hot water in the pipe factory are the same, but the lines are changed.

When we produce hot water pipes and cold water pipes, we basically use the same material, but when we make hot water pipes, the lines are changed to red, and when we make cold water pipes, the lines are changed to green.