Drinking Water Resources
Public Water System PFAS Information and Resources
In April 2019, the State Water Board issued specific orders to airports, landfills and adjacent water systems, identified as potential PFAS source locations. Data from more than 600 water system sites adjacent to nearly 250 airports with fire training areas and municipal solid waste landfills within California have been received by the State Water Board in response to these specific orders. The assessment of this data obtained by these actions is a prolonged undertaking and additional analysis will be conducted in the coming years. Selection of the location of public water supply (PWS) wells sampled was based on the following criteria:
- Within 2 miles of a commercial airport* and/or within 1 mile of a municipal solid waste landfill that received Investigative Orders on March 20, 2019
- Resampling of PWS wells sampled during the 2013-2015 US EPA’s Third Unregulated Contaminant Monitoring Rule (UCMR 3)
- Within 1 mile of UCMR 3 sampled PWS wells that had detections of PFOA and PFOS
*Certified by Federal Aviation Administration per Title 14 Code of Federal Regulations Part 139
The specific orders issued by the Division of Drinking Water required the Public Water Systems to sample the PWS wells quarterly for four consecutive quarters. The results of the PWS wells sampled during the 1st Quarter are now available for the public to view.
The data on this webpage may be incomplete and/or subject to change as new information becomes available. Future updates will include continued quarterly PWS monitoring data, additional PWS data identified through source investigations, and Department of Defense data.
Public Water Supply Well Results
The State Water Board is providing interactive maps and charts of the results on this webpage. These interactive maps reference to the terms “Notification Level” (NL) and “Response Level” (RL).
What is a Notification Level?
A notification level (NL) is a nonregulatory, precautionary health-based measure for concentrations of chemicals in drinking water that warrant notification and further monitoring and assessment.
What is a Response Level?
A response level (RL) is a nonregulatory, precautionary health-based measure that is set higher than a notification level and represents a recommended chemical concentration level at which water systems consider taking a water source out of service or provide treatment if that option is available to them.
Additional information about PFOA and PFOS can be found at can be found at the DDW PFOA and PFOS webpage.
To find the name of a PWS provider nearest you or for a particular location, use the following link to map your location or enter an address:
To find contact information for a PWS provider, use DDW’s Drinking Water Watch website at the following link and enter the ‘Water System Name’:
- The dataset of PFAS results for the PWS wells sampled during the 1st, 2nd, 3rd, and 4th Quarter is available for download in this file: (pfas_monitoring_Q1Q2Q3Q4)
- In this dataset and on the following maps and charts, if a water system sampled a well more than once in a quarter, the concentration equals to the average concentration for that analyte. Additionally, PFOA or PFOS concentrations reported at less than the reporting limit are shown as zero.
Maps and Charts
Four maps present the PWS well data in various levels of complexity – from the simplest only showing PFOA and PFOS concentrations at each sampled PWS well to the most complex map showing all 18 PFAS compounds at each PWS well sampled. The maps will allow to the user to toggle between the different quarters of data available. Users hovering their cursor over the PWS well on the map will provide a popup dialog box showing information about the well, including activity status. The activity status is defined as follows:
- Active – a source that is actively used to produce and distribute water to the distribution system
- Standby – a source that may only be used only for short-term emergencies of five consecutive days or less, and for less than a total of fifteen calendar days a year
- Offline – a source that is inactive and not permitted to produce and distribute water to the distribution system until such time that approval has been received
- This map is the simplest of the three maps provided. It displays drinking water results data for PFOA, PFOS, and the sum of PFOA and PFOS based on pre-selected concentration groups (less than the NL, between the NL and the RL, between the RL and 100 parts-per-trillion (ppt), and greater than 100 ppt).
- This map provides more flexibility than Map #1. The user may select drinking water results data for PFOA, PFOS, or the sum of PFOA and PFOS, pre-selected concentration groups (same as Map #1), and pre-selected locational groups. The locational groups are based on proximity to airports, landfills, and UCMR3 sampled PWS wells.
- This map provides the most flexibility to view the data. The user may select drinking water results for all of the PFAS chemicals analyzed, pre-selected concentration groups (same as Map #1 and #2), and pre-selected locational groups (same as Map #2). To toggle between different quarterly results, use the navigational arrows at the bottom center of your browser window.
- A series of two charts are shown. Each chart shows the frequency of detections for PFOA and PFOS, respectively for all results less than 70 ppt for PFOA or PFOS. The first column along the X-axis is equal to the NL for PFOA (5.1 ppt) or PFOS (6.5 ppt). Each column within each concentration range represents a quarter of data.
- A series of two charts are shown. Each chart shows the frequency of detections for PFOA and PFOS, respectively for all results for PFOA or PFOS. Each column within each concentration range represents a quarter of data.
- This chart displays the frequency of detections versus PFAS class. The PFAS classes used are:
- PFCAs = PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFTrDA, PFTA;
- PFSAs = PFBS, PFHxS, PFOS;
- FOSAs = NMeFOSAA, NEtFOSAA;
- PFECAs = HFPO-DA, ADONA;
- Cl-PFESAs = 11Cl-PF3OUdS, 9Cl-PF3ONS
Perfluoroalkyl acids (PFAAs) include PFCAs and PFSAs. Each column within each chemical class represents a quarter of data.
How to Use the Interactive Map
The view of the map can be changed by clicking and holding on the image to move it around and by clicking on the “+” or “-“ in the upper right to change the scale of the map. To the right of the map is Concentration, Chemical, or Location criteria to choose from – depending on the map. The map will change based on the selection of these items.
Data presented on each map is explained below:
- The circle represents a location of a sampled well.
- The color of the circle matches the maximum concentration of PFOA, PFOS and (PFOA + PFOS) detections. Hover your mouse pointer over the circle to see details (i.e. name of the water system, water system facility well ID, DDW’s Public System (PS) code, and a listing in tabular format of the detected concentrations for PFOA, PFOS, and Sum of PFOA and PFOS). If PFOA or PFOS were not detected in the sample, then a “ND” (represents Not Detected) is listed in the table.
- The color of the circle match the same colors presented on the bar chart (to the right of the map), as follows:
- Light Blue – Concentrations less than notification level (NL)(the sum of PFOA + PFOS concentrations)
- Yellow – Concentrations between the NL and the Response Level (RL) (the sum of PFOA + PFOS concentrations)
- Light Orange – Concentrations between the RL and 100 parts per trillion (ppt)
- Dark Red – Concentrations of PFOA + PFOS greater than 100 ppt
How to Use the Concentration, Chemical, or Location Criteria
To the right of the map are a series of criteria to choose from. Based on the type of map (Map #1, Map #2, Map #3), the selection criterion changes, as follows:
- Map #1 – Concentration ranges only (Less than the NL, Between the NL and the RL, Between the RL and 100 ppt, and greater than 100 ppt).
- Map #2 – Concentration, Chemical, and Location. The selection criterion for Concentration is the same as Map #1. For Chemical, the criterion are: PFOS, PFOA, and combination of PFOA and PFOS. For Location, the choices are based on the selection criterion explained the Background Section above.
- Maps #3 – The same as Map #2, except the list of Chemicals have expanded to include all of the PFAS compounds analyzed (14 analytes per US EPA Method 537, rev 1.1 or 18 analytes per US EPA Method 537.1) Hold down the “CTRL” key to select multiple concentration ranges or chemicals.
Click on the different Concentration ranges to highlight sources that fall within the selected range.
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In May 2016, the United States Environmental Protection Agency (US EPA) issued a lifetime health advisory for PFOS and PFOA for drinking water, advising municipalities that they should notify their customers of the presence of levels over 70 parts per trillion (ppt) in community water supplies. US EPA recommended that customer notifications include information on the increased risk to health, especially for susceptible populations.
In July 2018, DDW established an interim notification level of 14 ppt for PFOA and 13 ppt for PFOS and a single response level of 70 ppt for the combined concentrations of PFOA and PFOS.
In August 2019, DDW revised the notification levels to 6.5 ppt for PFOS and 5.1 ppt for PFOA. The single health advisory response level (for the combined values of PFOS and PFOA) remained at 70 ppt.
On February 6, 2020, DDW issued updated drinking water response levels of 10 ppt for PFOA and 40 ppt for PFOS based on a running four-quarter average.
Priority Basin Project
In cooperation with the U.S Geological Survey (USGS), the GAMA Priority Basin Project provides a comprehensive statewide assessment of groundwater quality to help identify and understand the quality of our groundwater resource. The project began sampling public water system wells to assess the deeper groundwater resource typically used for public supply in 2002 (Public Supply Assessment) and shifted to phase two in 2013 by sampling domestic and small system wells to assess the more shallow groundwater resource used for domestic and small system supplies (Shallow Aquifer Assessment). Since 2002, the USGS has performed baseline and trend assessments for each study unit and has sampled over 3,000 wells to characterize the quality of the complete aquifer resource used for all drinking water supplies. The Shallow Aquifer Assessment is currently sampling its 11th study unit.
The GAMA Priority Basin Project began the analysis of PFAS compounds in the summer of 2019 by adding twenty-eight PFAS compounds (which include carboxylates, sulfonates, precursors, and next generation-polyfluoroether “replacement” compounds) to the regular sampling schedule. This means wells sampled for both the Shallow Aquifer Assessment study units in progress and the trends component wells (sampling occurs at 20 percent of previously sampled wells, every five years in both the Public Supply and Shallow Aquifer Assessments) will undergo this PFAS schedule. Data from these assessments are released quarterly and available for query/download from the GAMA Groundwater Information System (GAMA GIS).
If you have any questions about the GAMA Program PFAS sampling, please contact Dori Bellan at Dorian.Bellan@waterboards.ca.gov.
From 2013 to 2015, the US EPA, under the Unregulated Contaminant Monitoring Rule (UCMR 3), required all large water systems (i.e., water systems serving over 10,000 people) nationwide to collect and analyze more than 12,000 drinking water samples for PFOS and PFOA. In addition, some water systems serving less than 10,000 people reported approximately 400 drinking water results for PFOS and PFOA. This occurrence data identified 36 sources with PFOS detections and 32 sources with PFOA detections. A summary of the findings for California is available at: https://www.epa.gov/dwucmr/occurrence-data-unregulated-contaminant-monitoring-rule
In March 2019, the Division of Drinking Water issued Health and Safety Code 116400 Orders to 600 water system sites, and nearly 250 locations such as airports with fire training and response areas, and municipal solid waste landfills are being reported to the State Water Boards and will continue to be collected until into early 2020. More water system data will be requested in the area of other types of sources in 2019, including industrial sites. The assessment of this data will be used to determine data information gaps. Additional and more assessment will be required in the coming years.
Some analytical methods using liquid chromatography-mass spectrometry-electrospray ionization methods (LC/MS/ESI) can achieve reporting limits for PFOA and PFOS at the nanogram per liter (ng/L) level. For the UCMR 3 monitoring program, LC/MS/MS-EPA Method 537 (rev 1.1) was required with minimum reporting limits of 20 ng/L and 40 ng/L for PFOA and PFOS, respectively. In November 2018, revised US EPA Method 537.1 was published that can detect PFOA, PFOS, and 16 other per-and polyfluorinated alkyl substances. Compliance with the recently changed NLs to 5.1 ng/L (PFOA) and 6.5 ng/L (PFOS) will require reporting limits lower than what can be achieved with US EPA Method 537. US EPA Method 537.1 is reported to be able to achieve lowest concentration minimum reporting levels (LCMRL) of 0.82 ng/L (PFOA) and 2.7 ng/L (PFOS). An LCMRL is defined as the lowest true concentration for which the future recovery is predicted to fall, with 99% confidence, between 50 and 150% recovery of the matrix spike (US EPA, Method 537.1, 2018).
Further information regarding PFAS in drinking water may be found at the Division of Drinking Water PFOA/PFOS webpage. (https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/PFOA_PFOS.html).
- Drinking Water District Offices Map
- Example PFOA/PFOS Notification Letter: (PDF)
- PFAS Water Systems Orders - April 30, 2019
- Drinking Water Sample Collection for PER and POLYFLUORINATED ALKYL SUBSTANCES (PFAS) Sampling Guidance REVISED May 2020
- General Order Requiring Monitoring for PFAS in Drinking Water Sources
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