PFAS are a category of manufactured chemicals used in a wide range of products that until recently, were not regulated by the EPA. 

These chemicals have a range of uses from everyday household items to industrial applications due to their heat, moisture, stain resistance and non-stick qualities. These chemicals don’t easily break down in the environment and can accumulate in the human body over time, earning the nickname “forever chemicals.” 

Common sources of PFAS are chemical compounds used for decades to repel water, grease and oil. They are found in products such as shampoo, pesticides, carpets, clothing, nonstick cookware, food packaging, plastic coatings, dental floss and some firefighting foam. These compounds don’t easily breakdown, therefore, they persist in the environment long after their initial use. 

Products containing PFAS that are discarded in the trash or flushed directly down drains can enter wastewater collection or stormwater conveyance systems. PFAS have been found in rainwater, wastewater, drinking water, soil, air, food, dust, animal samples and humans. 

Some possible health effects attributed to high levels of certain PFAS may include increased cholesterol levels, changes in liver enzymes, small decreases in infant birth weight, decreased vaccine response, increased risk of kidney or testicular cancer, increased high blood pressure or preeclampsia in pregnant women. 

In the 2000s, following EPA negotiations with manufacturers, a voluntarily phase out began for PFOA and PFOS, which are two types of PFAS. Now, PFOA and PFOS are no longer produced in the United States. However, some of these chemicals are still being produced in other countries and imported to the United States.   

See the EPA's PFAS webpage. 

The EPA oversees the National Primary Drinking Water Regulations, which establishes standards and regulatory limits called Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs). MCLs are legally enforceable levels, while MCLGs are non-enforceable, and represent goals for drinking water providers to achieve where feasible. 

On April 10, 2024, the Environmental Protection Agency (EPA) established new regulations for PFAS in drinking water. The new regulations established individual MCLs and MCLGs for five PFAS compounds, and a Hazard Index to account for the combined and co-occurring level of three of these PFAS compounds and one additional PFAS component in drinking water. These regulatory limits become effective on April 10, 2029, which allows time for water systems to implement treatment technologies. 

See the EPA’s regulations per compound.  

Tempe remains in compliance with all federal drinking water regulations. Safe drinking water is one of Tempe's highest priorities. As a proactive approach to maintaining public health and safety, Tempe will continue researching, designing, constructing and implementing treatment and operational strategies to meet regulatory standards. 

Additionally, in a separate effort, Tempe, the EPA, and the Arizona Department of Environmental Quality (ADEQ) have been collaborating on the clean-up of the South Indian Bend Wash (SIBW) Superfund Site for an organic compound called Trichloroethene. The EPA is reviewing PFAS presence in the SIBW. Find more information about this project at https://www.epa.gov/superfund/indianbendwash. 

Tempe remains in compliance with all federal drinking water regulations. Safe drinking water is one of Tempe's highest priorities. This section describes a timeline of Tempe’s PFAS-related actions. 

2009 

The EPA established the first provisional health advisory levels (HALs) for two PFAS compounds, perfluorooctanoic acid (PFOA) at 400 parts per trillion (ppt) and perfluorooctane sulfonate (PFOS) at 200 ppt. The EPA's health advisories are non-enforceable and non-regulatory levels meant to provide technical information to states agencies and other public health officials. 

2013 - 2014 

PFAS in potable water became a topic of interest at the national, state and local level. As part of the EPA’s program to monitor unregulated contaminants, Tempe collected samples for several unregulated contaminants at eight drinking water wells and its two water treatment plants. The purpose of this monitoring was to gather data to support the EPA in making decisions regarding whether to regulate it in the future. As part of this effort, Tempe monitored its water sources and distribution system for 28 unregulated contaminants including six different PFAS compounds. The monitoring results were published in Tempe’s annual consumer confidence reports. 

2016 

The EPA established a lifetime HAL for combined PFOA and PFOS at 70 ppt. In response, Tempe suspended use of three wells with PFAS levels near the HAL. These wells remain suspended from use today. 

2019 

As discussions continued in the drinking water community regarding future regulatory standards for PFAS, Tempe proactively conducted a study to determine available technologies to achieve PFAS removal to levels below probable future regulatory standards. Treatment design was started at three wells and construction was anticipated to be completed by Fiscal Year 2024-2025. It was anticipated that future treatment projects may be needed at Tempe’s water treatment plants and additional wells to meet then-anticipated PFAS regulatory standards. 

2022 

The EPA replaced the 2016 combined HAL for PFAS with updated individual lifetime HALs based on more recent studies regarding health effects, better analytical methods, and available treatment technologies. The interim HAL for PFOA was lowered to 0.004 ppt and the interim HAL for PFOS was lowered to 0.02 ppt. These levels were below what current approved analytical methods could detect. The EPA also issued health advisories for two additional PFAS compounds that had been used as replacement compounds in chemical and manufacturing for PFOA and PFOS. Hexafluoropropylene oxide dimer acid and its ammonium salt (GenX), replacement compound for PFOA, HAL was issued at 10 ppt and Perfluorobutane sulfonic acid (PFBS), a replacement compound for PFOS, was issued at 2000 ppt. 

2023 

On March 14, 2023, EPA announced proposed National Primary Drinking Water Regulations (NPDWR) for six PFAS chemicals. The proposal listed perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS) standards individually. Perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX Chemicals), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS) as a combined calculated standard. The proposed PFAS NPDWR did not require action until the rule’s finalization. 

2024  

On April 10, 2024, the Environmental Protection Agency (EPA) established new regulations for PFAS in drinking water. The new regulations established individual MCLs and MCLGs for five PFAS compounds, and a Hazard Index to account for the combined and co-occurring level of three of these PFAS compounds and one additional PFAS component in drinking water. These regulatory limits become effective on April 10, 2029, which allows time for nationwide water providers to implement treatment technologies. 

Tempe continues to: monitor for PFAS on a quarterly basis at its water sources and proactively design and prepare to implement treatment strategies to comply with these regulations prior to the EPA’s deadline of April 10, 2029. Tempe has procured laboratory instrumentation that will test for PFAS at Tempe’s State Certified Water Quality Laboratory. 

2025

The following table summarizes the range of levels detected in Tempe water in parts per trillion (ppt) or the unitless calculation for Hazard Index for each compound from water sources used in 2025: 

  * Hazard Index is a unitless standard and is not ppt 

To learn more about this group of chemicals, read the ADEQ's PFAS 101 Fact Sheet.

• EPA’s PFAS Strategic Roadmap and Health Advisories
• Arizona Department of Environmental Quality (ADEQ)https://azdeq.gov/pfas-resources
• ADHS: https://azdhs.gov/preparedness/epidemiology-disease-control/environmental-health/environmental-public-health-tracking/index.php#pfas
• EPA: https://www.epa.gov/pfas#
• EPA Questions and answers on PFAS https://www.epa.gov/sdwa/questions-and-answers-drinking-water-health-advisories-pfoa-pfos-genx-chemicals-and-pfbs
• CDC/ATSDR PFAS: https://www.atsdr.cdc.gov/pfas/about/?CDC_AAref_Val=https://www.atsdr.cdc.gov/pfas/health-effects/overview.html
• NSF: https://www.nsf.org/knowledge-library/perfluorooctanoic-acid-and-perfluorooctanesulfonic-acid-in-drinking-water