HDPE is the best for now if ...
Published by Engr. Olufemi AYILARA, OGUN STATE WATER CORPORATION, ABEOKUTA, NIGERIA - AREA BUSINESS MANAGER (OTA)
HDPE is the best for now if you can afford it. Ductile iron is good also but ensure joints are thrust adequately. Stay away from galvanized iron is highly corrosive, I would recommend PVC as normal practice.