Plumbing-code tag recommends keeping Washington amendments, advises not adopting most new 2024 UPC appendices

Members of the Mechanical Ventilation and Plumbing Codes (MVP) technical advisory group, meeting under the State Building Code Council process, reviewed the 2024 Uniform Plumbing Code (UPC) significant changes and existing Washington state amendments and moved to carry forward staff recommendations to not adopt most new appendices and to retain the state's existing amendments across the UPC chapters.

The tag examined the list of new and revised appendices in the 2024 UPC, discussed potential conflicts with Washington Administrative Code and Department of Health backflow and drinking-water rules, and voted to recommend that the council follow staff recommendations on adoption. Tag members also voted repeatedly to retain existing Washington state amendments in chapters 1 through 17 of the UPC, while flagging a small number of sections for follow-up code-change proposals.

Why it matters: Washington adopts the UPC with a set of state amendments and only the appendices specifically adopted by state law (RCW). The tag’s recommendations guide the Standing Committee and, ultimately, the Building Code Council as the state opens the public code-change proposal window. Changes adopted into the state code could affect plumbing design, water-safety practices (including backflow and Legionella guidance), and local permitting.

What the tag decided

- Appendices: After reviewing the “significant code changes” document and the new appendices added to the 2024 UPC (for example, Appendix N on Legionella guidance; Appendix O for non‑sewered sanitation;…