DBI proposes removing circuit‑venting section from body of plumbing code, commission approves case‑by‑case approach

Steve Penelli, Chief Plumbing Inspector, requested that San Francisco delete the circuit‑venting section (Section 911) from the local adoption of the 2016 California Plumbing Code and revert the approach to treating combination waste‑and‑vent systems as an appendix/alternate means handled on a case‑by‑case engineered basis. Penelli said the circuit‑venting provision had historically lived in an appendix and that moving it into the body of the code created a risk: undocumented systems can be altered during frequent tenant improvement work, risking loss of venting balance and trap seal integrity, and potential sewer‑gas intrusion.

DBI staff emphasized their intent: not to ban engineered combination systems, but to require they be submitted, documented in plans, reviewed and approved so future remodels and inspectors can find and preserve them. Commissioners and plumbing staff discussed public‑health tradeoffs and whether mechanical engineering and construction industry stakeholders had been consulted; Penelli said outreach to other jurisdictions found varied practice and that large projects typically present engineered plans while smaller projects rarely use the approach.

The commission voted to approve the proposed deletion from the body of the code and to continue allowing combination systems upon engineered submittal and DBI review, with documentation retained in project files. The motion passed unanimously.