Illinois Plumbing Code Practice 2025 – 400 Free Practice Questions to Pass the Exam

Unions are indeed not permitted in drainage and venting systems when considering the requirements set forth by the Illinois Plumbing Code. While it is true that unions offer a way to connect piping that allows for easy disconnection for maintenance or replacement, their use is restricted specifically due to concerns about potential leakage and blockage.

In drainage systems, all joints must be secure and leak-free to ensure efficient flow and to prevent sewer gas leaks. This requirement is more critical in drainage and vent systems, where any failure could lead to significant health hazards and property damage.

Typically, the plumbing code emphasizes the need for permanent joints, such as solvent-welded, threaded, or mechanical joints that provide the necessary strength and leak-proof performance in these systems. Using keystone connections like unions introduces variability that might compromise the effectiveness and reliability of the drainage and venting systems.

It is also worth noting that while unions may be acceptable in some other areas of plumbing work, such as supply lines, the critical nature of drainage and venting systems calls for more stringent standards to safeguard public health and maintain effective plumbing operations.