Which two plastics are typically used for water service lines?

• A. Polyvinyl Chloride and Polyethylene
• B. Polypropylene and Polycarbonate
• C. Polystyrene and Polyethylene
• D. Polyvinyl Chloride only

Answer: (A)

The main idea is that potable water service lines are typically made from plastics that resist corrosion, handle underground conditions, and have reliable joining methods. The best combination is rigid PVC and polyethylene. PVC works well underground: it’s durable, corrosion-resistant, and home/municipal crews have long experience with solvent-cement joints that create a tight, watertight seal. Polyethylene, especially HDPE, is highly flexible and forgiving in areas with soil movement, yet still strong enough for pressure flow; it’s joined by heat fusion to form long, continuous runs and resists chemical attack. The other plastics listed don’t fit as well for service lines because they either don’t have the same track record for potable-water pressure, can be too brittle, or lack widely adopted fittings for underground use.