The blaze at Pima Utilities started Wednesday afternoon in an area that treats wastewater with chemicals, such as chlorine, for the retirement community, fire officials said.
About four or five other hazardous chemicals could have been in the area, prompting emergency crews to evacuate all homes within a half mile of the plant.
Homeowners were notified by an automated telephone call. Residents were allowed back in their homes by nightfall.
Sun Lakes Fire Chief Richard Pawluk said the threat of contamination was quickly dispelled by a stiff wind.
Investigators were gathering air and water samples to determine if any poisonous chemicals were involved.
Pawluk said the chemical blaze at the plant, which serves Sun Lakes' 16,000 residents, did not affect the drinking water.
Information from East Valley Tribune/Scottsdale Tribune
