Common specifications and models of PE water supply pipes are usually differentiated by their outer diameter and wall thickness.

Common outside diameters include 20mm, 25mm, 32mm, 40mm, 50mm, 63mm, 75mm, 90mm, 110mm, 125mm, 140mm, 160mm, 180mm, 200mm, 225mm, 250mm, 280mm, 315mm, 355mm, 400mm, 450mm, 500mm, 560mm, and 630mm.

Wall thickness varies depending on the pressure class and outer diameter. Generally, common pressure classes include SDR11 (Standard Dimension Ratio) and SDR17.6.

It's important to note that the specific model selection should be determined based on actual engineering requirements, usage environment, and pressure demands, among other factors.