Tucson Water identified two contaminated wells and has taken them out of service.
According to department spokesman Fernando Molina, the wells are located just north of Davis-Monthan Air Force Base. They detected PFOS/PFOA compounds, also known as perfluoroalkyl substances.
According to the Environmental Protection Agency, the substances are used for firefighting at airfields and have been found to potentially cause cancer, birth defects, liver damage and immune system problems.
"The wells have only minimally been used for the past few years and have been taken out of service," Molina said in a statement. "We are in the process of collecting water samples from adjacent wells (to) better determine how far the contaminants may have spread."