What Is Rule 9-6 / Standard 301.5? (The California Water Heater Law 2027)
Rule 9-6 is a Bay Area Air Quality Management District rule focused on reducing nitrogen oxide emissions from natural gas-fired boilers and water heaters.
Standard 301.5 specifically addresses certain natural gas-fired storage tank water heaters with a rated heat input capacity of 75,000 BTU/hour or less. Under the rule, covered units manufactured after January 1, 2027 must meet a zero-NOx emissions standard.
That sounds technical because, well, it is. But for homeowners, the main takeaway is much simpler:
When your water heater needs to be replaced in the future, the type of replacement equipment available may change.
This is especially relevant if your current water heater is older, inefficient, leaking, rusting, or already giving you hints that retirement is near. If you’re not sure what shape your system is in, our gas water heater repair and installation team can help you figure out whether repair, maintenance, or replacement makes the most sense.