By Marcelle Dibrell
With federal policy stepping back, California regulations are driving the future of gas pool heaters.
The future of gas-fired pool heaters may be decided in California, where a combination of energy standards and emissions rules is redefining how pool heating systems are designed and installed.
With the recent federal repeal of the EPA’s greenhouse gas endangerment finding, policy direction for gas-fired appliances is increasingly set at the state and local level, with the stringent jurisdictions — particularly California — likely to drive industry trends. In February 2026, the Trump administration repealed the EPA’s greenhouse gas endangerment finding, a 2009 determination under the Clean Air Act that concluded greenhouse gases such as carbon dioxide and methane endanger public health and welfare. That finding had provided the legal basis for federal regulation of greenhouse gas emissions for more than a decade.
The repeal shifts emissions policy toward state and regional air quality programs, which still regulate nitrogen oxide (NOx) under ozone standards — a key driver of smog. Those requirements are pushing reductions from combustion equipment, including gas-fired pool and spa heaters.
In regions where air quality does not meet federal smog standards, such as parts of California, regulators are required to implement additional NOx reductions.
One example is Southern California’s South Coast Air Quality Management District (South Coast AQMD), regulating air pollution across LosAngeles, Orange, Riverside, and San Bernardino counties, a region with some of the most persistent smog challenges in the country.
The district’s amended Rule 1146.2, adopted in June 2024, requires many residential and commercial water heating appliances — including natural gas pool and spa heaters in the 75,000 Btu/hr to 2 MMBtu/hr range — to meet a near-zero NOx emissions standard when equipment is replaced. The rule applies as equipment reaches the end of its service life and affects roughly 1 million units, including an estimated 700,000 pool and spa heaters.
The rule is currently being challenged in federal court in Rinnai America Corp. v. South Coast Air Quality Management District. Manufacturers, including Rinnai, along with trade groups such as the Pool & Hot Tub Alliance (PHTA), argue that it conflicts with the federal Energy Policy and Conservation Act (EPCA) by effectively eliminating federally certified gas appliances.
EPCA establishes national energy efficiency standards and generally preempts state and local rules — meaning federal law overrides conflicting requirements — that attempt to regulate appliance efficiency or fuel use. Challengers argue that, although the AQMD rule is framed as an emissions standard, its practical effect is to prohibit gas-fired equipment allowed under federal law.
In 2025, the U.S. District Court for the Central District of California upheld the AQMD rule, finding that it regulates air pollutant emissions — specifically nitrogen oxides — rather than energy efficiency or fuel type. The court also acknowledged that the rule would “effectively ban” covered gas-fired appliances. The case is now on appeal before the U.S. Court of Appeals for the Ninth Circuit.
It is important to distinguish this case from California’s statewide energy standards. The state’s updated Title 24 energy code, which took effect January 1, 2026, requires that new pool and spa heating systems use a heat pump, solar, or another qualifying renewable source as the primary heat source. Gas-fired heaters remain allowed, but only in a supplemental role. As a result, in new construction and first-time heating installations, gas heaters are already being pushed into a secondary position.
Unlike the AQMD rule, Title 24 operates through building energy standards and does not directly regulate emissions or fuel type, which is why it has not faced the same type of legal challenge.
The AQMD rule addresses a different segment of the market. Rather than shaping new construction, it applies at the point of equipment replacement. If upheld, it would extend similar limitations to existing pools as heaters reach the end of their service life.
If the rule is upheld on appeal, it could provide a legal framework for other air districts and states to adopt similar emissions-based standards. While not a nationwide decision, such a finding would likely serve as a precedent for regulators in other regions.
When it comes to environmental policy, a pattern has become familiar: As California goes, so goes the nation. The state has historically set aggressive standards in areas such as vehicle emissions and energy efficiency, and manufacturers have often aligned product design with California’s requirements rather than producing separate versions for different markets.
A similar dynamic could emerge in pool heating. If large markets adopt emissions-based standards that limit gas-fired equipment, manufacturers may increasingly prioritize electric or non-combustion technologies. Over time, that shift could influence product availability, pricing, and the long-term role of gas-fired pool heaters — even in regions without comparable regulations.
In some respects, the repeal of the EPA’s greenhouse gas endangerment finding may produce the opposite of its intended effect. By reducing federal oversight, it shifts greater influence to state and local regulators — where stricter jurisdictions are already shaping the direction of the industry.
The result may not be less regulation, but a shift in where — and how — those rules are set.
Related: While some California rules govern new construction and equipment replacement, yet another state regulation may determine what equipment remains on the market at all. See “Push Back On Carb Heater Proposal” on page 19.
