Guide · Updated October 11, 2026
The Bay Area's zero-NOx water heater rule: what it means for your next heater.
If your water heater is working, this rule asks nothing of you today. It only applies when you replace one. Here is where it stands as of October 11, 2026, in plain terms.
The short version
- The rule applies to new water heaters at replacement, not to the one already in your garage.
- The adopted rule sets a zero-NOx standard for residential-size water heaters manufactured after January 1, 2027.
- A draft amendment published July 14, 2026 would push that to January 1, 2028 and add exemptions.
- The Air District Board holds a public hearing on the amendments on November 4, 2026. Until it votes, 2027 is still the rule on the books.
What the rule is
Bay Area Air District Regulation 9, Rule 6 has limited nitrogen oxide (NOx) emissions from gas-fired water heaters since 1992. In March 2023 the Board amended it to set a zero-NOx standard. In practice, ordinary gas-burning tanks can't meet that standard, which is why it's often described as a "gas water heater ban". Heat-pump (electric) water heaters can.
Which heaters, and when
- Under 75,000 BTU/hr, typically residential tank water heaters: zero-NOx for units manufactured after January 1, 2027 under the adopted rule.
- 75,000 to 2 million BTU/hr, typically commercial and multifamily units, and including tankless: January 1, 2031 under the adopted rule. The July 2026 draft would move this class to January 1, 2033.
The standard applies at the point of sale and installation. It does not require you to remove or retrofit a heater that's already installed.
The proposed delay and exemptions
On July 14, 2026 the Air District published draft amendments that would delay the residential date from January 2027 to January 2028. The Air District expects most exemptions to fall into three groups:
- Low-income property owners, including participants in programs such as Medi-Cal or CalFresh, and households paying more than 28 percent of their income toward their mortgage and property taxes
- Space-constrained properties without enough room or ventilation for a compliant unit
- Electrical limitations, such as panels below 100 amps, insufficient panel capacity, or needing to run electrical lines more than 50 feet
These are proposals. The Board is scheduled to consider them at a public hearing on November 4, 2026, and we'll update this page after it votes.
What it means if your heater is getting old
Nothing changes for a working heater. If yours is past ten years old, or showing the warning signs (water at the base, rusty hot water, rumbling), it's worth knowing your options before it fails, because a failed heater forces a fast decision:
- Know your panel. A heat-pump water heater needs electrical capacity near where it goes. If your panel is small or far away, that shapes both your options and whether an exemption could apply.
- Know your space. Heat-pump units need room and airflow that a tight closet may not have.
- Don't panic-buy. Replacing a healthy heater early just to beat a date usually isn't worth it. Replacing a failing one on your schedule instead of the heater's usually is.
Call (408) 868-5710 and we'll talk it through for your house, including when the honest answer is to wait.
Sources: Bay Area Air District, "Air District publishes draft changes to water heater rule" (July 14, 2026); Building Appliances Rule Implementation; Rules 9-4 and 9-6 rule development. This page is general information, not legal advice. Check the Air District's site for the current status.
Planning your next water heater?
Call and we'll walk through gas, heat pump and tankless for your house, and tell you if it can wait.