Polyethylene Supply PipeHDPE (High density polyethylene) and MDPE (medium density) are strong, robust pipes suitable for underground water installations. They are harder and more rigid than LDPE (low density) and can withstand higher water pressures. HDPE is the ideal choice for general irrigation as it is a durable water pipe that can be easily connected to compression fittings. MDPE blue polyethylene pipe is suitable for potable water systems and LDPE is used to transport water from the source to a micro (or feeder) pipe for delivery to emitters.