Rule,Who it binds,What it does to gas furnaces or water heaters,Key date,Status on 2026-11-02,Source
Bay Area Air District Rule 9-4,Sale and installation in the San Francisco Bay Area air district,"Zero-NOx standard for furnaces under 175,000 BTU/hr",Units made after 2029-01-01,Adopted 2023; date unchanged,s9
Bay Area Air District Rule 9-6,Same,Zero-NOx standard for water heaters,"Small tank units: proposed move to 2028-01-01; units above 75,000 BTU/hr to 2 million BTU/hr: proposed 2033",Board hearing on the 2026 amendments set for 2026-11-04,s9
South Coast AQMD Rules 1111 and 1121 (proposed zero-emission amendments),Southern California air district,Would have required zero-emission furnaces and small water heaters,Board vote 2025-06-06,Rejected 7 to 5; earlier rule text stays in force,s10
CARB zero-emission space and water heater standard,"Statewide, California",Concept stage,FAQ updated 2026-07-13,Not finalized; not yet proposed to the Board,s11
DOE furnace and water heater efficiency standards,Nationwide,Efficiency minimums (not a fuel ban),Supreme Court order 2026-06-08,Judgment upholding the rules vacated and remanded to the D.C. Circuit,s13