Southern California Boiler and Water Heater Regulation

In Southern California, a rule adopted in June 2024 targets industrial boilers and water heaters fueled by fossil gas, driving a major shift toward electric boilers and heaters. Regulators in the South Coast Air Quality Management District voted to approve a first-in-the-nation measure that aims to sharply reduce emissions of smog-forming nitrogen oxides (NOx) from more than 1 million large water heaters, small boilers, and process heaters in the area. Starting in 2026, smaller units in new buildings must meet zero-emission limits. The last required to make the switch are existing facilities with high-temperature units, which have until 2033.

Boilers and water heaters covered by Southern California’s new rule account for about 9 percent of all NOx emissions from stationary sources in the region. When fully implemented by 2033, the measure is expected to reduce pollution by 5.6 tons of NOx per day — the equivalent of slashing half of all smog-forming emissions from cars in the region.