Per- and polyfluoroalkyl substances, a chemical family known as PFAS, were developed in the 1930s and 1940s and are now used in a wide variety of waterproof and oilproof containers, clothes, and implements, as well as firefighting foam. However, PFAS compounds’ ubiquity means that they have also made their way into water supplies that are used for human consumption, potentially causing serious health consequences. Orange County Water District (OCWD) is one groundwater management agency that is working with federal, state, and local agencies to test, identify, and monitor PFAS. 

In this interview, Jason Dadakis, OCWD’s executive director of water quality technical resources, speaks with Municipal Water Leader Managing Editor Joshua Dill about the occurrence and risks of PFAS and what OCWD is doing to combat them. 

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Joshua Dill: Please tell us about your background and how you came to be in your current position. 

Jason Dadakis: I’m a hydrogeologist by training, and I have worked for OCWD for about 15 years. My current title here at OCWD is executive director of water quality technical resources. I work with our analytical laboratory, water quality monitoring programs, regulatory compliance, and research and development. 

Joshua Dill: Would you give us an overview of OCWD? 

Jason Dadakis: OCWD is what’s known in California as an independent special district. It was created by the state legislature in the 1930s and charged with the role of managing the local groundwater basin. We are the groundwater basin manager for north and central Orange County. There are 2.5 million people in our service area, and the groundwater basin currently provides 77 percent of the water supply. Our major stakeholders are the 19 retail water agencies that have wells that pump from the basin and serve water to residential and industrial customers. 

Joshua Dill: What are PFAS chemicals and where do they come from? 

Jason Dadakis: PFAS is a family of thousands of different chemicals that were developed for a wide range of industrial and commercial uses beginning in the 1930s and 1940s. Over time, the family has expanded as certain compounds have been phased out for a variety of reasons and new ones are brought to market. 

Some water-resistant fabrics are manufactured with PFAS compounds

Joshua Dill: What kind of products are they found in? 


Jason Dadakis: PFAS compounds impart distinctive chemical properties of water, oil, and stain resistance. They are widely used in carpets that have been treated to protect against stains, food wrappers that are impermeable to grease, pans that have been coated with Teflon and other coatings, Goretex jackets, and other waterproof items. Another major user of PFAS is the military, particularly for aircraft operations. Aqueous film-forming foam, or AFFF, which uses PFAS compounds, was developed to put out jet fuel fires quickly and effectively. This foam is widely used at military facilities all over the United States and the world, especially at airfields. It has now been found that those activities release these chemicals into the environment. 

Joshua Dill: How do PFAS compounds get into water that people might end up drinking? Do they leach out of products in landfills? 

Jason Dadakis: The environmental fate and transport of these contaminants is still an emerging field of research. PFAS compounds are ubiquitous in the environment because of their widespread usage in a range of consumer products. The frequent use of these chemicals at military facilities in training activities and demonstrations is one source. Typically, after these training activities, many of these foams are simply released or washed into the environment and the soil. That’s one way they’ve been found to get into the groundwater. Another source is manufacturing facilities themselves, both through discharges of industrial wastewater and atmospheric deposition via stack emissions. Occurrence at landfills is related to PFAS compounds’ widespread use in consumer products that are then disposed of in landfills. We are also learning more about the presence of the compounds in conventionally treated municipal wastewater as well. 

Joshua Dill: How common are these chemicals in water? 

Jason Dadakis: With the improved analytical technology that has emerged over the last decade or so, these compounds are being found in lots of places. Through federal government programs like the National Institute of Health’s biomonitoring program, which has been looking for these compounds in human blood serum across the country for almost 20 years, PFAS have been found in 98–99 percent of the U.S. population. The compounds are persistent and tend to bioaccumulate. The two most studied compounds of the family are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), both of which have been phased out in the United States. They tend to persist and bioaccumulate. Both compounds, I believe, have been found to have half-lives in humans of about 3–5 years. 

Joshua Dill: Are PFAS chemicals more prevalent in certain regions as opposed to others? 

Jason Dadakis: The initial places where they were discovered were communities with major manufacturing facilities and military facilities. One thing that’s driven the discovery of these compounds is that, during 2013–2015, the U.S. Environmental Protection Agency (EPA) had its third Unregulated Contaminant Monitoring Rule (UCMR3) program that required medium- to large-size drinking water systems to test for PFAS compounds. That revealed a more widespread occurrence of these compounds than had been expected in areas of the country that had not yet been investigated. That and certain follow-up investigations by individual states have revealed the widespread presence of these compounds in various environmental mediums, including soil, air, and water. 

Joshua Dill: What are the possible dangers to human health posed by these chemicals? 

Jason Dadakis: We know the most about PFOA and PFOS, although I would say the understanding is still evolving on those as well. There’s evidence of human health effects even at fairly low concentrations, in the parts-per-trillion level, especially when coupled with long-term exposure. The fact that PFAS compounds, especially PFOA and PFOS, do tend to stick around the human body and are not eliminated quickly is a factor. 

Our understanding of these effects has been driven by whole-animal studies on the toxicology side, looking at the effects on rodents and other animals. There have also been some human epidemiological studies that have traced certain outcomes, especially in places where there’s documented human workplace exposures. These two compounds tend to concentrate in the kidneys, and a probable link with kidney cancer has been documented, along with ulcerative colitis and thyroid diseases. There are also some issues with neonatal or prenatal exposures with certain outcomes, like immunotoxicity leading to things like vaccinations not being effective in children that have been exposed to PFOA and PFOS. 

Joshua Dill: When did OCWD become aware of the issue with PFAS and decide to do something about it? 

Jason Dadakis: The UCMR3 program first put it on our radar screen. Our lab is one of three public agency labs in the nation to provide a full UCRM3 program. OCWD laboratory and water quality staff conducted the unregulated contaminant monitoring on behalf of the major retail water agencies in our groundwater basin, and PFAS was one of the chemical families that was included. That gave us an initial snapshot of the occurrence of these compounds in our groundwater basin. 

Joshua Dill: How is the district monitoring and treating its water now?

Jason Dadakis: The district is not a retail agency; we don’t serve finished drinking water to anyone. You can think of us as the groundwater wholesaler in the area. Where we do get directly involved in the treatment of these compounds is in advanced water treatment related to recycled water. The district operates the largest indirect potable reuse facility in the world, known as the Groundwater Replenishment System (GWRS). It’s a 100 million gallon-per-day facility that takes secondary treated wastewater effluent that would normally be discharged into the Pacific Ocean, purifies it with an advanced treatment process, and then uses it for groundwater replenishment. Knowing that PFAS compounds can occur in conventionally treated wastewater, we made sure to test our advanced treatment recycled water to make sure that we were not introducing them into the groundwater basin through our GWRS recharge activities. That testing, which is going to be going on for a number of years, has verified that our advanced treatment process, which is centered on reverse osmosis, is an effective barrier for PFAS compounds. 

A handful of the retailers that are pumping groundwater had certain wells that tested at above the levels established by the 2016 EPA lifetime health advisory for PFOA and PFOS. As soon as they became aware of that in 2016, those wells were immediately shut down and taken out of service. Since that time, the State of California has established its own similar nonenforceable advisories for PFOA and PFOS. The current California interim response level and the EPA lifetime health advisory carry similar advisory recommendations that water with a combined concentration of PFOA and PFOS greater than 70 parts per trillion not be served to the public. 

Moving forward, though, and aware that those standards may be changing and becoming more strict, both OCWD and the retail agencies are embarking on a number of efforts to assess the feasibility of the treatment of the groundwater supply, including pilot testing studies to establish some capital operating costs for potential future treatment facilities and planning studies. Granular activated carbon is the best available technology for PFOA and PFOS removal from drinking water. Ion exchange is also emerging as a viable alternative, and significant research is being conducted to develop improved sorbents that are effective across the range of PFAS compounds. 

Joshua Dill: So the reverse osmosis process OCWD was already using to treat its water is effective in removing some of these compounds? 

Jason Dadakis: That’s correct. We have been testing our GWRS product water with the current EPA method for PFAS, Method 537 Revision 1.1, and the targeted PFAS compounds have consistently been nondetect. That makes sense, given the properties of PFAS compounds. Their molecular size and ionic charge lend themselves to good removal by reverse osmosis. 

Joshua Dill: What advice do you have for other municipal water suppliers about detecting and treating water that might contain PFAS? 

Jason Dadakis: The best thing to do is to arm yourself with information. Learn about the properties of the compounds and try to keep up with the public health studies. Be as proactive as you can in monitoring and understanding the occurrence of these compounds in your water supplies. That can allow utilities to lead the dialogue in their communities about PFAS occurrence and about what is known and what is still unknown about these compounds on the public health side. This will lay a foundation to discuss potential expenses that may be reflected in customer rates. Starting that dialogue early is a proactive way to approach the issue. 

Jason Dadakis is executive director of water quality technical resources at the Orange County Water District. He can be contacted at