Is it permissible to drill a hole in a clean-out cap to make sewer access more accessible?

• A. yes
• B. only with a permit
• C. no
• D. insignificant, not prohibited

Answer: (C)

Modifying a clean-out cap by drilling into it is not permissible because clean-outs are designed to be sealed to prevent sewer gases and pests from entering the living space and to provide a controlled access point for maintenance. Drilling an opening compromises the seal, can create new paths for odors or hazardous gases, and may weaken the cap or interfere with the intended protection of the piping system. Building and plumbing codes require clean-outs to be readily accessible and unobstructed, and any access enhancements should use approved methods and components rather than altering the cap itself. If access is an issue, pursue an approved solution such as an appropriate access fitting or relocating/reconfiguring the clean-out with a licensed professional, rather than drilling.