When sourcing HDPE liners, the most critical factor is thickness, typically ranging from 0.5mm to 3.0mm depending on the water pressure and terrain. You must ensure the material is made from 100% virgin high-density polyethylene resins to guarantee maximum longevity. Key performance indicators include tensile strength (ASTM D6693), puncture resistance (ASTM D4833), and carbon black content (2-3%) for UV protection. For ditch applications, a textured surface may be required if the slope is steep to increase friction with the soil or concrete cover.