For private interceptor main sewers 6 inches or larger, where must a manhole be located?

• A. At the most downstream point
• B. At the most upstream point
• C. Only at the beginning
• D. At every branch connection

Answer: (B)

Access to the private interceptor for maintenance and testing is the main idea here. A manhole serves as a readily available entry point to inspect, clean, and vent a gravity sewer, and for a 6-inch or larger private interceptor, placing that access at the most upstream point gives you direct reach to the portion of the line closest to the building where blockages and solids typically originate. With the manhole at the upstream end, you can more easily perform cleaning and inspection on the private side before waste travels farther toward the public sewer, and it helps isolate the private line for testing or maintenance without needing multiple access points downstream.

Placing a manhole downstream, or only at the very beginning, or at every branch connection would complicate maintenance and add unnecessary access points. The upstream location provides essential, practical access where it’s most needed for proper upkeep of the private interceptor.