2027 UPC/UMC: Review Legionella, hydrogen piping, auto repair garage and indoor EV fast-charging changes

What IAPMO published

The International Association of Plumbing and Mechanical Officials says it published the 2027 editions of the Uniform Plumbing Code and Uniform Mechanical Code in hardcopy and electronic versions on June 11, 2026. IAPMO says publication completed a three-year consensus development process accredited by the American National Standards Institute. Source: https://iapmo.org/newsroom/press-releases/iapmo-publishes-2027-editions-of-upc-umc.

The supplied official IAPMO pages announce publication and summarize changes. They do not establish that the 2027 editions are enforceable in any specific state, city or project. For any job-specific decision, owners should check the adopted code edition, project specifications and the authority having jurisdiction.

Plumbing items to review

IAPMO’s 2027 UPC summary lists changes covering adult changing stations, laminar-flow faucets in healthcare facilities, water-heater sizing, flow-through expansion tanks, well components, drainage and vent vacuum testing, sewer and storm-sewer rehabilitation, gray water, building water management for Legionella and scalding, safe operation, closure and reopening of building water systems, hydrogen fuel gas piping, and onsite wastewater treatment for direct potable water reuse.

Two UPC items are especially safety-sensitive and should be read from the code materials before being turned into scope language or pricing assumptions. IAPMO says the 2027 UPC updates Appendix N for building water management planning and monitoring to reduce Legionella and scalding risks. It also says the 2027 UPC adds Appendix Q for safe operation, closure and reopening of building water systems.

IAPMO also says the 2027 UPC adds Appendix U as recommended practice for hydrogen fuel gas piping systems and Appendix V with minimum requirements for onsite wastewater treatment systems for direct potable water reuse. The supplied summary does not provide the full code text for those appendices.

Mechanical items to review

IAPMO’s 2027 UMC summary lists changes covering exhaust ventilation for auto repair garages, indoor DC fast-charging EV spaces and LP-gas facilities; personnel certification pathways for testing, adjusting and balancing and duct leakage testing; laboratory exhaust; radioactive-material exhaust; grease duct leakage testing; refrigeration systems; masonry heaters; district energy; Legionella in mechanical systems; hydronic heat-transfer-fluid configurations; hydrogen fuel gas piping; and mechanical systems for tiny houses.

IAPMO says the 2027 UMC adds Appendix H with minimum requirements to address Legionella growth in mechanical systems. It also says the UMC adds Appendix K with recommended configurations for maintaining quality of heat-transfer fluids in closed-loop hydronic systems, Appendix M as recommended practice for hydrogen fuel gas piping systems, and Appendix O addressing minimum mechanical system requirements for tiny houses.

For refrigeration work, IAPMO’s summary says the 2027 UMC updates provisions including releasable refrigerant charge limits under the EDVC framework, machinery rooms, and refrigerant piping and shaft requirements. The supplied summary does not provide installation procedures or design details.

How owners can use the change list

Use IAPMO’s list as a triage document, not as a substitute for the code books. This is an editorial recommendation based on the listed subject areas; the supplied IAPMO pages do not provide contractor-specific findings on cost, training, permitting or inspection impacts.

Plumbing owners may want to flag recurring work involving healthcare faucets, water-heater sizing, expansion tanks, wells, vacuum testing, sewer rehabilitation, gray water, building water management, building reopening, hydrogen fuel gas piping or direct potable reuse. HVAC and mechanical owners may want to flag auto repair garage ventilation, indoor DC fast-charging spaces, LP-gas facilities, TAB and duct leakage testing credentials, lab exhaust, grease duct testing, refrigeration, district energy, hydronic heat-transfer-fluid configurations, hydrogen piping and tiny-house mechanical systems.

Be careful with appendices. The supplied IAPMO materials identify several items as appendices, recommended practices, recommended configurations or minimum requirements. They do not explain which provisions become enforceable in a jurisdiction after adoption or how optional appendices are handled locally.

For training and background review, IAPMO says 2027 UPC and UMC Illustrated Training Manuals and Guides to Important Code Changes are available as educational resources. IAPMO also says the 2024 technical committee meeting monographs contain every code-change proposal submitted for the 2027 UPC and UMC, and the 2025 monographs contain every public comment submitted for the 2027 editions. Sources: https://iapmo.org/newsroom/press-releases/iapmo-2024-code-change-monographs-now-available and https://iapmo.org/newsroom/press-releases/iapmo-code-change-monographs-now-available-2025.

2030 proposals are already open

IAPMO says it opened the call for formal code proposals for the 2030 UPC and UMC on July 17, 2026. Proposals must recommend new text, revised text or deleted text in legislative format and clearly state the reason for the recommendation.

IAPMO says proposals can be submitted at https://codeproposals.iapmo.org after creating an account. It says no proposals will be accepted after 5 p.m. PDT on Jan. 8, 2027. Source: https://iapmo.org/newsroom/press-releases/iapmo-solicits-proposals-for-2030-upc-and-umc.

The supplied pages do not provide 2027 UPC or UMC errata, addenda, tentative interim amendments or formal interpretations, and they do not state that none exist. Before using a provision for a safety-sensitive design, inspection dispute or training document, check current IAPMO code resources and the code books themselves.