Which pipe material cannot be used on the exterior of a building or underground?

Which pipe material cannot be used on the exterior of a building or underground?

• A. PVC
• B. Aluminum
• C. Copper
• D. Steel

Answer: (B)

When choosing pipe for exterior or buried use, the material must stand up to moisture, soil chemistry, and physical wear over time. Aluminum isn’t well suited for those conditions because it can corrode more readily in damp or backfilled environments and can be prone to galvanic corrosion when it sits next to other metals like copper or steel. It also isn’t as easy to join reliably in buried installations, and there aren’t as many proven, long‑term fittings and coatings available for aluminum in underground or outdoor service. PVC, copper, and steel are commonly rated for exterior or buried use: PVC resists moisture and soil chemicals well and is easy to trench and install; copper has strong corrosion resistance for water lines; and steel (often galvanized) offers durability and structural strength for buried or exposed outdoor runs. So aluminum is not typically used for exterior or underground piping.

When choosing pipe for exterior or buried use, the material must stand up to moisture, soil chemistry, and physical wear over time. Aluminum isn’t well suited for those conditions because it can corrode more readily in damp or backfilled environments and can be prone to galvanic corrosion when it sits next to other metals like copper or steel. It also isn’t as easy to join reliably in buried installations, and there aren’t as many proven, long‑term fittings and coatings available for aluminum in underground or outdoor service.

PVC, copper, and steel are commonly rated for exterior or buried use: PVC resists moisture and soil chemicals well and is easy to trench and install; copper has strong corrosion resistance for water lines; and steel (often galvanized) offers durability and structural strength for buried or exposed outdoor runs. So aluminum is not typically used for exterior or underground piping.