Replace the gas water heater now or wait? The Bay Area rule, date by date

Somewhere in your house there's a gas water heater: in the garage under a Sunset row house, a back-porch closet in a Mission flat, the basement of a Berkeley brown shingle. If it's getting old, you've probably heard it's about to be banned. Not quite. The Bay Area Air District regulates which water heaters can be sold and installed, not the one already strapped to your wall, and the date it set is being reconsidered. Here is where things stand on October 3, 2026, and how to decide about your tank.

#What the rule bans, and what it leaves alone

Regulation 9, Rule 6 is an air-quality rule about nitrogen oxides, the NOx that forms when natural gas burns and feeds smog and fine-particle pollution. On March 15, 2023 the Air District's Board amended it, along with Rule 9-4 for furnaces, to set a zero-NOx standard for gas storage water heaters rated at 75,000 BTU per hour or less: the ordinary household tank. The Air District calls these point-of-sale emission standards. Per its own fact sheet and staff report, they leave alone:

• A working heater. Existing water heaters can stay in operation until they burn out or need replacing.
• Selling your house. Replacing equipment triggers the rule; a property sale doesn't.
• Stoves, ovens and dryers. They aren't covered, and the Air District says it has no plan to regulate them.
• Propane. Only natural gas equipment falls under the rule.
• Mobile homes. Their water heaters are exempt from the zero-NOx standard.

The detail most coverage skips: the cutoff follows the tank's date of manufacture. The rule bars selling or installing a gas tank made after the compliance date that emits any NOx, so a tank built before the date can still be sold and installed after it. The October 2026 proposal would also put the manufacture date on every carton and rating plate.

So what is a zero-NOx water heater? For now, an electric one. The Air District says the only appliances on the market that currently meet the standards are electric. For most households that means a heat pump water heater, which takes heat from the surrounding air and puts it into the water. An electric resistance tank also complies, because the rule only covers heaters that burn natural gas.

#The dates, in order

1. March 15, 2023

   The Board adopts the standards

   Rules 9-6 for water heaters and 9-4 for furnaces are amended together, each with a zero-NOx date.

2. July 14, 2026

   A first draft

   Staff publish draft amendments: a one-year delay for household tanks, plus exemptions.

3. October 2, 2026

   The formal proposal

   Proposed rule language, a staff report and a hearing notice come out. The income exemption now reaches owners at or below 80% of area median income.

4. November 1, 2026, 6 p.m.

   Comments close

   Comments go through the Air District's online comment tool or by mail; the notice says emailed comments can't be considered.

5. November 4, 2026, 9 a.m.

   The Board hearing

   At 375 Beale Street in San Francisco and on Zoom, with spoken comments taken.

6. 2027

   January 1: the adopted date

   Gas tanks of 75,000 BTU/hr or less made after this date can't be sold or installed, unless the Board changes the rule.

7. 2028

   January 1: the proposed date

   If adopted, the standard moves here for tanks over 30 gallons, and sellers must post a notice that a gas tank needs an exemption certificate.

8. 2029

   January 1: furnaces

   Rule 9-4 reaches furnaces under 175,000 BTU/hr made after this date, which is still under review.

9. 2031, or 2033 if amended

   January 1: larger and tankless gas units

   Heaters from 75,001 to 2 million BTU/hr, typically tankless, commercial and multifamily units in the Air District's words.

#Who the October proposal would exempt

Every exemption in the proposal runs through one document: an exemption certificate from the Air District, obtained before the gas tank is installed, whose number the seller and the installer then keep on record. The preliminary staff report says eligibility rests mostly on self-attestation, and that certificates are planned to be issued immediately once every field of the application is complete.

#Replace now or wait? Work it out for your tank

There's no single right answer, but there is a right order of questions. Start with the tank's age, because that tells you how much time you actually have; the staff report works from an average service life of about 13 years for a replacement heater. Then look at what would make a heat pump hard in your house.

#What a heat pump water heater asks of an older house

A gas tank needed a flue, a gas line and a cold-water inlet. A heat pump unit trades the flue for a different set of needs, and in a house built in the 1920s those needs land in awkward places. Tap the numbers to see where a contractor will look.

Old wiring is the hidden variable. BayREN notes that knob-and-tube wiring is common in Bay Area homes built before the 1950s, and the proposal names it: where a house has knob-and-tube and the new heater would need more than 50 feet of conduit to the panel or subpanel, a contractor's certification qualifies the address for the one-time exemption. Any new circuit is C-10 Electrical work; the electrical page covers panels, rewiring and load.

#If the tank fails after the cutoff

1. Stop the water

   Close the cold-water valve above the tank and protect the floor; the first 48 hours guide covers drying out.

2. Smell gas? Follow PG&E's rule

   Leave, call 911, then PG&E at 1-800-743-5000. PG&E says to shut gas off at the meter only if you smell gas, hear it escaping, see a broken line or suspect a leak, and never to turn it back on yourself.

3. Read the plate

   Gallons, BTU rating and manufacture date decide which rule applies. Under the proposal, tanks of 30 gallons or less keep the older low-NOx limit, since staff found no zero-NOx model that small on the US market.

4. Check exemptions before buying

   The certificate comes before the installation, never after.

5. Ask about the stopgap

   Under the proposal, a licensed contractor can install a temporary gas tank with a certificate, then must remove it within 12 months or qualify it under another exemption.

6. Permit, straps and license

   Expect a permit and an inspection either way. Check the license at cslb.ca.gov: C-36 Plumbing covers water heating equipment and gas connections, and C-20 includes water heating heat pumps.

#The furnace is next: Rule 9-4 and 2029

What people call the Bay Area's gas furnace ban is Rule 9-4: a zero-NOx standard for furnaces under 175,000 BTU per hour made after January 1, 2029. Like the water heater rule, it applies at replacement, never to a furnace that still runs. The staff report says that date is being evaluated, with a full report due this fall, and the Air District has promised a cost and technology assessment before 2029. Staff don't recommend pushing the water heater date past 2029, partly to avoid confusion with furnaces.

The two rules meet at the electrical panel. If the furnace and the water heater are both near the end, plan them together so the electrical work happens once. A hydronic system, where one gas appliance heats both the water and the house, would fall under the proposal's 2033 provision rather than the 2028 date.