What is the primary role of mains in a modern water distribution system?

• A. To store water before distribution
• B. To distribute water under pressure to feeders
• C. To treat water at the source
• D. To drain water back to the source

Answer: (B)

The mains are the backbone of the distribution network, carrying treated water under pressure from the treatment plant to feeder mains. This pressure-enabled flow ensures water can reach service areas across the system and supply households, businesses, and fire protection outlets through the smaller feeder lines. Storage tanks and reservoirs provide the needed volume to meet peak demand, but they are separate from the mains’ job of delivering water under pressure. Treatment occurs upstream at the plant, not in the mains, and draining water back to the source is not the purpose of the mains.