The current plumbing and fittings are generally made of PVC material. The PVC pipe is well installed. It is completely self-contained. It is not worse than the construction team. Even if you are too lazy to do it, it is best to design it yourself. The workers are doing. Down pipe fittings, general basins, sinks, water pipes are 50, 40, 32. These numbers represent the diameter of the pipe, which is 5 cm, 4 cm, 3.2 cm. The pipe fittings are also of such specifications. Commonly used pipe fittings include down pipe, tee, 90 degree elbow, 45 degree elbow and return bend.
There are also various diameters, which can connect different types of tubes together. There are two types of water return bends, one is round and the other is triangular. The water return bend is round in the figure below. There is more room for maneuver.