Per- and Polyfluoroalkyl Substances (PFAS)

Map of Tucson Water wells tested for PFOA and PFOS
Map of Tucson Water wells tested for PFAS

Updated Dec. 17, 2019

Dec. 17 Mayor and Council Study Session presentation: Per- and polyfluoroalkyl Substances (PFAS) pdf

PFOA and PFOS FAQs from ADEQ (Nov. 2019) exiting Tucson Water website

This page has up-to-date information on Tucson Water's management of per- and polyfluoroalkyl substances (PFAS, sometimes also called perfluorinated compounds or PFCs) in the water system. 

Keeping Your Water Safe from PFAS

Tucson Water delivers safe, clean, and high quality water that meets state and federal regulations. The utility also voluntarily monitors the water system for hundreds of contaminants that are not regulated by federal, state, or local governments.

In 2016, the United States Environmental Protection Agency (EPA) issued an updated health advisory for two types of PFAS, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). The EPA issues health advisories for contaminants that it does not regulate, but which may pose a risk to public health. The current health advisory for PFOA and PFOS is set at 70 parts per trillion – one part per trillion is roughly equivalent to one drop of water in 20 Olympic-sized swimming pools.

What are per- and polyfluoroalkyl substances (PFAS)?

PFAS are a large group of manufactured compounds that have been widely used to make everyday products – such as cookware, sofas, and carpets – more resistant to stains, grease, and water. PFAS are also used in a type of firefighting foam known as aqueous film-forming foam (AFFF), which is used to fight petroleum fires. In the United States, awareness is emerging of widespread wildlife and human exposure to several PFAS, including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Both PFOA and PFOS are byproducts of other commercial products, meaning they are released into the environment when other products are made, used, or discarded. PFOS is no longer manufactured in the US, and PFOA production has been reduced and will soon be eliminated.

Where have PFOA and PFOS been detected in Tucson's groundwater?

To date, testing indicates that PFOA and PFOS are present in specific areas, and do not occur in the majority of our groundwater supply. Tucson Water has been testing for PFAS since 2009 as part of its Sentry Water Quality monitoring program (a voluntary program to proactively look for unregulated compounds in our water supplies), and has detected PFOA and PFOS at wells in northwest Tucson, in the vicinity of Davis-Monthan Air Force Base (DMAFB), in the TARP well field, and some wells associated with the Reclaimed Water System. We have also found high levels of PFAS in groundwater north of Tucson International Airport, in an area that does not supply groundwater to Tucson Water's system. A map showing potable production wells that have been tested, and the status of wells where PFAS were detected, is at the top of this page.

In 2001, Tucson Water began conversion of its primary water supply to Colorado River water, delivered through our Clearwater Facilities in the Avra Valley. Testing of our Clearwater facilities at multiple points has confirmed that there are no detectable concentrations of PFOS and PFOA in that supply, which now provides about 80% of Tucson’s overall potable water supply. 

Is there a risk to public health posed by the presence of PFAS in Tucson's groundwater?

Based on all currently available information, public health is not at risk in the Tucson Water system. Tucson Water is not serving and has not served water that is above the Health Advisory level set by the EPA.

Tucson Water’s primary obligation is to provide safe drinking water to its customers, and we look to a wide number of experts and regulatory requirements to guide our decisions. Tucson Water works closely with the EPA and other agencies as they work toward establishing safe minimum risk levels. This includes maintaining communications with EPA staff and reviewing current research, such as the Agency for Toxic Substances and Disease Registry’s (ATSDR) "Toxicological Profile for Perfluoroalkyls." Tucson Water has established operating protocols for wells with detections of PFAS, based on the most current data available. Specifically, Tucson Water has disconnected from the distribution system any wells with PFOA/PFOS concentrations above the current Health Advisory of 70 ppt (parts per trillion) and has restricted operation of any wells with detectable concentrations of PFOA/PFOS to emergency situations (e.g. fire flow), even if the compounds are present below the Health Advisory level. When wells with detectable levels of PFAS are taken out of service, water from clean sources is brought into those delivery zones. In addition, operation of the TARP facility continues, and monitoring confirms that treated water is below the current Health Advisory level for PFAS.

It should be noted that the EPA did not advise water providers to monitor for PFAS until 2009. When PFAS were discovered at northwest side wells in 2009, the levels detected were below the established Health Advisory levels at that time. When Health Advisory levels for PFOA and PFOS were reduced in 2016, Tucson Water responded by immediately removing affected wells from service.

What does the future hold?

  • Wells that exceed the Health Advisory will remain offline.
  • Expanded and continued sampling of Tucson’s various wells and water supplies will continue.
  • Investigation of the Davis-Monthan Air Force Base site and groundwater in the northwest area of the aquifer will continue.
  • Research into containment and treatment options will continue.
  • Ongoing research of the occurrence, fate, and transport of PFAS will continue, and management actions will be taken if necessary.

What effort is being made to inform the public?

There has been significant effort to inform the public, including:

Video: Director Tim Thomure answers customer's questions about PFAS and water quality during a Facebook live Q&A on September 26, 2018

For more information, call Tucson Water's Public Information and Conservation Office at (520) 791-4331.