Which pipe type is no longer installed in the United States?

• A. PVC pipe
• B. Gray cast-iron pipe
• C. Ductile iron pipe
• D. HDPE pipe

Answer: (B)

Gray cast-iron pipe has largely been phased out in new water distribution projects in the United States. It was used historically, but its drawbacks—susceptibility to corrosion, brittleness, heavier weight, and more demanding joint repair—led utilities to transition to more durable and easier-to-install materials. Today, new installations favor ductile iron, PVC, or HDPE, which offer better longevity, corrosion resistance, and installation practicality. Existing gray cast-iron mains may still be in service, but they’re typically not the material chosen for new construction.