Air District Delays Zero-NOx Water Heater Rule

The Bay Area Air District Board voted to push the zero-NOx water heater compliance date to January 2028, adding exemptions for some households.

Updated on Nov. 5, 2026 in Utilities

Air District Delays Zero-NOx Water Heater Rule

Live Poll

Should local governments require homes to switch to electric water heaters when replaced?

The Bay Area Air District Board voted on November 4 to amend Rule 9-6, moving the compliance date for zero-NOx water heaters from January 2027 to January 2028. The standard applies only when an existing water heater is replaced and does not require removing working appliances.

Why it matters

The Air District estimates gas-fired water heaters and furnaces cause as many as 85 premature deaths and 15,000 asthma attacks in the Bay Area each year. The delay and new exemptions respond to questions the Board raised about cost and implementation.

The compliance date moves from January 2027 to January 2028, with multifamily and deed-restricted affordable housing deferred to January 1, 2033. Exemptions apply to panels below 100 amps and electrical runs over 50 feet, but the number of households affected was not stated.

The players

Bay Area Air District

The regional agency responsible for air quality regulation across the Bay Area, which has administered Rule 9-6 since its adoption.

The details

Rule 9-6 has limited NOx emissions from natural gas-fired water heaters since 1992, and the amendments add allowances for temporary installations in emergencies. Water heaters with capacity of 30 gallons or less and mobile home water heaters are not required to comply, and the standard does not apply to stoves, dryers, or fireplaces.

1992: Rule 9-6 first limited NOx emissions from gas water heaters.
2023: The Air District amended the rule to set a zero-NOx standard.
May 2026: The Board raised cost and implementation questions.
July 14, 2026: The Air District published draft amendments.
November 4, 2026: The Board voted to adopt the amendments.

Utility Context

The amendment extends Rule 9-6, which has limited NOx emissions from natural gas-fired water heaters since 1992. The new exemptions for low-income owners and space-constrained properties show the Air District balancing its 2023 zero-NOx standard against household cost concerns.

Homeowners who replace an existing gas water heater will need a compliant unit starting in January 2028 unless they qualify for an exemption. Households with a 100-amp panel or electrical runs over 50 feet may be exempt from the standard.

The takeaway

Homeowners planning a water heater replacement should check whether they meet the new low-income or space and electrical exemptions before the January 2028 compliance date. Checking eligibility early can make the transition to a compliant unit more affordable.