Water Supply Lakes

PFAS: Background and Impact

Per- and polyfluoroalkyl substances (PFAS) is a common term for a group of human-made chemicals found in everyday products. PFAS were originally created in the 1940s and are resistant to water, grease and stains. They are found in everyday items such as carpet, clothing, cookware, food wrappers and furniture. They are also used in some firefighting foams that are being phased out of use.

PFAS chemicals take a long time to break down and are thus persistent in the environment. Humans can be exposed to these chemicals through a variety of pathways, including eating food contaminated with PFAS, using products made with PFAS, drinking water that contains PFAS and breathing air containing PFAS. The Environmental Protection Agency (EPA) has found associations between exposure to some PFAS chemicals and human health.

drinking water

PFAS Have Not Been Detected Above the Reporting Limit in the City of Boulder Drinking Water.

In 2020, the City of Boulder proactively participated in a state-sponsored program to test for PFAS in drinking water and found no detections of PFAS compounds. To view a detailed list of the compounds not detected in Boulder’s water system, visit the Colorado Department of Public Health and Environment website.

In 2023, the city is conducting additional PFAS sampling in the finished drinking water as part of the Environmental Protection Agency’s Fifth Unregulated Contaminate Monitoring Rule. We have completed two of the four required sampling events, first quarter and second quarter of 2023. There are 29 PFAS compounds required in this sampling rule. The City of Boulder has had zero detections above the Reporting Limit (RL). The Reporting Limit for each compound is listed below.

Contaminant Minimum Reporting Level (RL) Quarter 1 2023 Quarter 1 2023 Quarter 2 2023 Quarter 2 2023
Betasso WTP Boulder Reservoir WTP Betasso WTP Boulder Reservoir WTP
EPA Method 533
11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) 0.005 µg/L < RL < RL < RL <RL
9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (9Cl-PF3ONS) 0.002 µg/L
4,8-dioxa-3H-perfluorononanoic acid (ADONA) 0.003 µg/L
hexafluoropropylene oxide dimer acid (HFPO DA) 0.005 µg/L
nonafluoro-3,6-dioxaheptanoic acid (NFDHA) 0.02 µg/L
perfluorobutanoic acid (PFBA) 0.005 µg/L
perfluorobutanesulfonic acid (PFBS) 0.003 µg/L
1H,1H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS) 0.005 µg/L
perfluorodecanoic acid (PFDA) 0.003 µg/L
perfluorododecanoic acid (PFDoA) 0.003 µg/L
perfluoro(2-ethoxyethane)sulfonic acid (PFEESA) 0.003 µg/L
perfluoroheptanesulfonic acid (PFHpS) 0.003 µg/L
perfluoroheptanoic acid (PFHpA) 0.003 µg/L
1H,1H, 2H, 2H-perfluorohexane sulfonic acid (4:2FTS) 0.003 µg/L
perfluorohexanesulfonic acid (PFHxS) 0.003 µg/L
perfluorohexanoic acid (PFHxA) 0.003 µg/L
perfluoro-3-methoxypropanoic acid (PFMPA) 0.004 µg/L
perfluoro-4-methoxybutanoic acid (PFMBA) 0.003 µg/L
perfluorononanoic acid (PFNA) 0.004 µg/L
1H,1H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) 0.005 µg/L
perfluorooctanesulfonic acid (PFOS) 0.004 µg/L
perfluorooctanoic acid (PFOA) 0.004 µg/L
perfluoropentanoic acid (PFPeA) 0.003 µg/L
perfluoropentanesulfonic acid (PFPeS) 0.004 µg/L
perfluoroundecanoic acid (PFUnA) 0.002 µg/L
EPA Method 537.1
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) 0.005 µg/L < RL <RL <RL <RL
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) 0.006 µg/L
perfluorotetradecanoic acid (PFTA) 0.008 µg/L
perfluorotridecanoic acid (PFTrDA) 0.007 µg/L
EPA Method 200.7
lithium 7439-93-2 < RL < RL < RL < RL
Betasso Water Treatment Plant

Boulder's Drinking Water

The city strives to provide clean, safe, great-tasting drinking water to its customers.
We are fortunate to have
several high-quality sources of water both east and west of the Continental Divide.

The city is committed to protecting our community and our resources. Both the State of Colorado and the EPA are moving quickly to understand potential health effects, mitigate sources of PFAS and develop PFAS regulations. We are actively evaluating new information and potential rules and regulations around PFAS to best protect the health of our drinking water system and our community.