PFAS

PFAS Information

Seattle's drinking water remains safe and protected from contaminants, including the group of man-made chemicals labeled PFAS (per- and polyfluoroalkyl substances).

PFAS are manufactured for a variety of industrial purposes. If detected in drinking water, PFAS have the potential to raise health concerns.

For more information about PFAS, including the health and safety risks associated with these compounds, visit the Environmental Protection Agency and Washington State Department of Health websites.

Although PFAS are not regulated contaminants and routine testing is not required, Seattle Public Utilities (SPU) tested its Tolt and Cedar River surface water sources for six types of PFAS in 2015. Test results in 2015 showed no detection of PFAS was found.

In October 2018, SPU conducted additional tests on the Tolt and Cedar water supplies, this time using a more sensitive sampling method and testing for 14 types of PFAS. Test results again showed no detection of PFAS and Seattle's surface water supplies continue to be safe and protected from contaminants. A summary of the 2018 tests are shown below.

In addition to the City's primary surface water sources, Seattle also has wells available for emergencies. The wells are not used very often, and they have not been used since 2015.

As a precaution, SPU tested the wells for PFAS in October 2018. Two of the three wells had no detection of PFAS. Trace detections of several PFAS compounds were measured in the third well with a maximum concentration of 5 parts per trillion (see table). This amount is far below the health advisory level of 70 parts per trillion established by the U.S. Environmental Protection Agency (EPA).

 

Results Summary October 2018

All results in ug/L.

PFC Compound NameAcronymCedarToltRiverton1Riverton2Blvd Park

N-ethyl Perfluorooctane sulfo namido acetic acid

NEtFOSAA

ND

ND

ND

ND

ND

N-methyl Perfluorooctane sulfo namido acetic acid

NMeFOSAA

ND

ND

ND

ND

ND

Perfluorobutane sulfonic*

PFBS

ND

ND

ND

ND

0.0018

Perfluorodecanoic acid

PFDA

ND

ND

ND

ND

ND

Perfluorododecanoic acid

PFDoA

ND

ND

ND

ND

ND

Perfluoroheptanoic acid

PFHpA

ND

ND

ND

ND

0.0029

Perfluorohexanesulfonic acid*

PFHxS

ND

ND

ND

ND

0.0022

Perfluorohexanoic acid*

PFHxA

ND

ND

ND

ND

0.0047

Perfluorononanoic*

PFNA

ND

ND

ND

ND

ND

Perfluorooctane sulfonic acid*

PFOS

ND

ND

ND

ND

ND

Perfluorooctanoic acid*

PFOA

ND

ND

ND

ND

0.0050

Perfluorotetradecanoic

PFTeDA

ND

ND

ND

ND

ND

Perfluorotridecanoic

PFTrDA

ND

ND

ND

ND

ND

Perfluoroundecanoic acid

PFUnA

ND

ND

ND

ND

ND

Sample Location

-

CLT-5

TPT-3

RHW1-R

RHW2-R

BPW-R

* Compound was also part of UCMR3. EPA Method 537 was used for all analyses. Method Reporting Limit was 0.002 ug/L for all analytes. Sample date for Cedar and Tolt was 10/08/2018. Sample date for the wells was 10/03/2018. Field blanks did not have any detections.