The main ones used in home decoration are 20mm and 25mm. These two are household hot water pipes. There are PPR standard and PPR antibacterial. If it is used for heating, you can use standard PPR. PPR water pipes are divided into cold and hot water pipes. The thickness of the pipes is different. Cold water pipes cannot be used as hot water pipes. The easy way to distinguish cold and hot water pipes is that there is a red line mark on the hot water pipe.