Per- and Polyfluoroalkyl Substances (PFAS)

Per- and polyfluoroalkyl substances, known as PFAS, are a group of manufactured chemicals that have been used in industry and consumer products since the 1940s because of their useful properties. One common and concerning characteristic of PFAS is that many break down very slowly and can build up in people, animals, and the environment over time.

According to the U.S. Environmental Protection Agency (EPA), because of the widespread use of PFAS and their persistence in the environment, many PFAS are found in the blood of people and animals all over the world and are present at low levels in a variety of food products and in the environment. PFAS are found in water, soil, air, and food as well as materials found in homes and workplaces. While research is ongoing, scientific studies have shown that exposure to some types of PFAS may be linked to harmful health effects in humans and animals. (source: epa.gov/pfas)

Extensive testing, including voluntary monthly testing for PFAS, shows Sioux Falls’ drinking water is well within all health-based limits set by the EPA and South Dakota Department of Agriculture and Natural Resources (DANR).

For more information about PFAS, including possible health effects, ongoing research, and ways to mitigate your exposure, visit epa.gov/pfas.

Frequently Asked Questions (FAQs)

What are PFAS?

Per- and polyfluoroalkyl substances, or PFAS, are a group of manmade chemicals that repel oil, grease, and water. Because of this, they may be used by manufacturers to keep food from sticking to cookware (Teflon), to make sofas and carpets resistant to stains (Scotchguard), to make clothes and mattresses more waterproof, and may also be used in some food packaging, as well as in some firefighting materials such as firefighting foam. Some products that use or previously used PFAS include dental floss, non-stick cookware, microwave popcorn bags, pizza boxes, fast food wrappers, outdoor gear with durable water resistant coatings, shampoo, nail polish, facial moisturizers, and eye make-up. Drinking water is only one of many potential sources where a consumer may be exposed to PFAS.

Have PFAS been detected in the Sioux Falls drinking water system?

Yes, levels of PFAS have been previously detected in the City of Sioux Falls’ water.

Since August 2016, monthly samples have been collected from the treated water at the City’s water plant and from the treated water purchased from the Lewis and Clark Regional Water System and analyzed for PFAS. All test samples are in compliance with U.S. Environmental Protection Agency (EPA) established levels.

As part of a 2011/2012 survey, drinking water samples were collected, and results were below the health advisory levels, but showed the presence of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS), two of the most widely used and studied chemicals in the PFAS group. In response to this information, the City initiated further testing of our water sources and ultimately suspended use of wells impacted by these substances.

In 2013, additional testing was conducted to identify potential sources of the PFAS. On a voluntary basis, the City discontinued use of wells where PFAS were found.

Additional water testing was performed in 2014, 2015, and 2016.

After the EPA finalized the PFOS and PFOA (both of which are part of the PFAS family of chemicals) Health Advisory levels in May 2016, additional water samples were collected. PFOS and PFOA compounds were detected below the health advisory levels once again, but did result in the proactive discontinued use of additional wells.

Why did the City of Sioux Falls begin testing for PFAS in the drinking water system?

The federal Safe Drinking Water Act requires testing of a number of unregulated substances every five years. The purpose of this testing, known as the Unregulated Contaminant Monitoring Rule (UCMR), is to collect data for substances suspected to be present in drinking water but that do not have established health-based standards under the Safe Drinking Water Act. This process provides a source of data used by the EPA in setting regulatory actions to protect public health. (EPA. 25, August 2016, retrieved from https://www.epa.gov/sites/production/files/2015-10/documents/ucmr3_factsheet_general.pdf)

The City participates in all UCMR studies and continues to monitor for PFAS chemicals by testing monthly its source water, treated water, and water purchased from the Lewis and Clark Regional Water System.

Is the water in Sioux Falls’ drinking water system safe to consume?

The City has completed the initial PFAS monitoring required by the EPA and the South Dakota Department of Agriculture and Natural Resources (DANR) from November 2023 through May 2024 and no detectable levels of PFAS were found in any of the drinking water samples. This testing, in addition to all monitoring required by the Safe Drinking Water Act, shows Sioux Falls’ drinking water is well within all health-based limits set by the EPA and DANR.

What is the City doing to protect the public from PFAS?

The Sioux Falls Water Division has implemented a monitoring program that includes monthly tests of treated water for PFAS. The City also tests water received from the Lewis and Clark Regional Water System on a monthly basis.

The City has proactively discontinued the use of any well where PFAS have been detected. In addition, all currently operating wells have been tested to ensure we are in compliance with all applicable federal, state, and local regulations.

Are PFAS regulated in the drinking water?

The EPA finalized drinking water standards for PFAS chemicals in April of 2024 for six (6) substances and are expected to be implemented across all water systems by 2027. The City, along with the South Dakota Department of Agriculture and Natural Resources (DANR), continues to monitor the information supplied by the EPA and its partners.

All drinking water samples that are voluntarily tested monthly by the City of Sioux Falls are below all regulatory maximum contamination levels that will go into effect in 2027.