Gas-powered pool heaters produce carbon monoxide as a byproduct of combustion — and the U.S. Consumer Product Safety Commission (CPSC) warns that a malfunctioning pool heater can produce CO at levels that accumulate near the pool water surface and kill swimmers without warning. In September 2026, CPSC issued a recall against Hayward Industries Universal Pool Heaters for producing high levels of carbon monoxide during operation — underscoring how real and immediate this hazard is as pool heaters are put to use in the fall season.
How Pool Heater CO Harms Swimmers
When a gas pool heater operates correctly, combustion byproducts are vented away from the pool area. When a heater malfunctions, develops a cracked heat exchanger, or has blocked or improper venting, CO can escape into the area near the pool rather than being safely exhausted. CO is heavier than air and can accumulate at low levels near the water surface — exactly where swimmers’ faces are. Because CO is colorless and odorless, swimmers may have no awareness of the hazard before experiencing symptoms.
CO poisoning symptoms during swimming — confusion, weakness, inability to maintain stroke — can be mistaken for exertion or cold water effects, delaying the recognition of an emergency. A swimmer who loses consciousness in water drowns before help can arrive.
What Every Pool Owner Must Do
- Have your gas pool heater professionally inspected at the start and end of every pool season. This includes inspection of the heat exchanger, burner, and all venting components.
- Never operate a gas pool heater with damaged, blocked, or improperly routed exhaust venting.
- Install a CO alarm near the pool equipment area and test it monthly.
- If any swimmer in your pool exhibits unexpected weakness, confusion, or difficulty swimming, remove everyone from the water immediately, move to fresh air, and call 911.
- Check SaferProducts.gov to verify whether your pool heater has been flagged or recalled.
To report a dangerous product or a product-related injury, visit SaferProducts.gov or call CPSC’s Hotline at 800-638-2772.
