PFAS In Drinking Water


PFAS, or per- and polyfluoroalkyl substances, are a group of human-made chemicals that have been widely used since the 1940s in various industrial and consumer products for their water- and grease-resistant properties. PFAS have unique chemical structures that include fluorine-carbon bonds, which make them resistant to heat, water, and oil. These properties have led to their use in a wide range of products, including non-stick cookware, water-resistant clothing, food packaging, and firefighting foams.

The concern surrounding PFAS arises from their persistence, bioaccumulation, and potential adverse health effects. Here's a brief overview of the history and reasons for concern:
  1. Proliferation in Consumer Products:

    • PFAS became popular in the manufacturing industry due to their unique properties.

    • They were used in various consumer products, including Teflon-coated cookware, water-resistant clothing, carpets, food packaging, and more.

  2. Environmental Persistence:

    • PFAS are highly persistent in the environment, meaning they do not break down easily. This persistence has led to their accumulation in soil, water, and air over time.

  3. Global Presence:

    • PFAS contamination is a global issue, with these substances being detected in water supplies, soil, and even remote areas where there is no direct industrial activity.

  4. Bioaccumulation:

    • PFAS can accumulate in living organisms, including fish and animals, and move up the food chain. This bioaccumulation raises concerns about potential health effects in humans who consume contaminated food and water.

  5. Health Concerns:

    • Information published by the Envionmental Protection Agency (EPA) can be found here: EPA's PFAS Website

Regulatory Actions

In response to growing concerns, the Envionmental Proptection Agency and the CT Department of Health Drinking Water Section have been working with Agency partners to implement lower maximum contaminant level (MCL) regulations for PFAS. The CT DPH has derived individual health-based drinking water Action Levels for 10 PFAS (CT Department of Health Action levels).

Action Levels are guidelines for drinking water that are protective of public health and also feasible based upon analytical detection and treatment technology. This means that an Action Level concentration can be detected in drinking water by certified laboratories and that treatment systems are available to remove the contaminant(s) to a concentration that is below the Action Level.

The 10 PFAS for which CT has developed Action Levels have enough toxicological data available to support development of health-based Action Levels. These PFAS include the most widely studied PFAS that have also been detected in human blood more frequently and at higher concentrations than other PFAS.CT DPH established Action Levels for four PFAS (PFOA, PFOS, PFNA, PFHxS) in June 2022 and for another six PFAS (GenX, PFHxA, PFBS, PFBA, 6:2 Cl-PFESA, 8:2 Cl-PFESA) in June 2023.

The current Action Levels are listed in the Table below:



CT Drinking Water Action Level
1 nanograms/L = 1 ppt
(nanograms per liter; ng/L)^


6:2 chloropolyfluoroether sulfonic acid (6:2 Cl-PFESA, 9Cl-PF3ONS,*

F-53B major)



8:2 chloropolyfluoroether sulfonic acid (8:2 Cl-PFESA, 11Cl-PF3OUdS,**

F-53B minor)



Perfluorooctane sulfonic acid (PFOS)



Perfluorononanoic acid (PFNA)



Perfluorooctanoic acid (PFOA)



Hexafluoropropylene oxide dimer acid (HFPO-DA; GenX)



Perfluorohexane sulfonic acid (PFHxS)



Perfluorohexanoic acid (PFHxA)



Perfluorobutane sulfonic acid (PFBS)



Perfluorobutanoic acid (PFBA)


EPA Methods 533 & 537.1 use9Cl-PF3ONS (9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid) for this PFAS.

** EPA Methods 533 & 537.1 use11Cl-PF3OUdS (11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid) for this PFAS.



What Has Southington Water Been Doing?

In recognition of the growing concern about PFAS, Southington Water has been voluntarily sampling for PFAS since 2019. These results, which were obtained by a laboratory certified by the state of Connecticut for PFAS analysis, showed that PFAS levels in our water supplies were less than the original advisory limit of 70 parts per trillion (ppt) defined by the Connecticut Department of Public Health (CT DPH) and United States Environmental Protection Agency (EPA).

Sampling Results

The most recent sampling was done on 10-25-2023 and PFAS was found to be present in Southington's drinking water at levels below the CT DPH Action Levels established for PFAS. Southington Water continues to closely monitor PFAS levels and future regulatory requirements.

PFAS (ppt) Highest Detected Level CT DPH Action Level Date Tested Action Level Exceedance
PFPeA 4 No Action Level 10/25/2023 No
PFBS 4 760 10/25/2023 No
PFHxA 4 240 10/25/2023 No
PFHxS ND 49 10/25/2023 No
PFHpA 2.49 No Action Level 10/25/2023 No
PFOA 8 16 10/25/2023 No
PFOS 5 10 10/25/2023 No
PFNA ND 49 10/25/2023 No
ppt = parts per trillion


Future Requirements

On March 14, 2023, EPA announced the proposed National Primary Drinking Water Regulation (NPDWR) to establish legally enforceable levels, called Maximum Contaminant Levels (MCLs), for six PFAS in drinking water. PFOA and PFOS as individual contaminants, and PFHxS, PFNA, PFBS, and HFPO-DA (commonly referred to as GenX Chemicals) as a PFAS mixture. EPA is also proposing health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these six PFAS.

Although this proposed rule does not require action until it is finalized before June 2024, Southington Water has been proactively working to meet the proposed NPDWR values represented in the table below: