Sewers located adjacent to a ground storage reservoir are required to be located at least 10 feet from the structure and be constructed of water main type materials for a distance of at least 50 feet from the storage reservoir. What is the reason for this requirement?

• A. To protect the storage reservoir from contamination
• B. To prevent a high ground water table adjacent to the reservoir
• C. To reduce infiltration into the sewer
• D. Vitrified-clay sewer pipe is easily broken

Answer: (A)

The key idea is protecting a potable water supply by preventing sewer-derived contamination around a ground storage reservoir. When a sewer is close to a storage reservoir, there’s a real risk that leaks, seepage, or backflow could introduce pathogens, chemicals, or other contaminants into the water stored for drinking. Requiring a minimum distance and using water main–type materials helps create a safer barrier: the separation reduces the chance that contaminants from the sewer can reach the reservoir area, and water main–type materials are designed to be durable and watertight in potable-water applications, minimizing leakage paths and infiltration that could carry contaminants toward the reservoir.

The other options don’t fit the intent as well. The rule isn’t about groundwater table conditions near the reservoir, or about reducing infiltration into the sewer itself, and it isn’t primarily about the relative fragility of vitrified-clay sewer pipe. The main purpose is to safeguard the storage reservoir from potential sewer contamination.