What testing method indicates infiltration and illegal connections?

• A. Dye Testing
• B. Pressure Testing
• C. Smoke Testing
• D. Visual Inspection

Answer: (C)

This is about how to reveal infiltration and illegal connections in a sewer system. Smoke testing works by blowing harmless smoke into the sewer network and watching where it escapes to the surface or through unintended openings. Any place where the smoke leaks out—through cracks, faulty joints, or connections that shouldn't exist (like a storm drain tying into a sanitary line)—shows up clearly, making hidden problems visible. That direct visualization of leaks and illegal ties is why this method is the best for identifying infiltration and unauthorized connections.

Dye testing, while useful for tracing flows and identifying cross-connections in plumbing fixtures, doesn’t reliably reveal underground infiltration points or illicit connections in the broader sewer network. Pressure testing focuses on whether pipes and joints hold up under pressure, which detects leaks in new installations but not infiltration from surrounding soil. Visual inspection can miss hidden leaks entirely, since many issues aren’t visible on the surface.