Best​​​ Practices for Collecting Water & Wastewater Samples to Test for PF​AS​​​​​

Per- and polyfluoroalkyl substances (PFAS) are an increasing health and environmental concern in the scientific community, and that concern is escalating among industrial, municipal and regulatory audiences.

The U.S. Environmental Protection Agency, the U.S. National Institute of Environmental Health Sciences, the U.S. Centers for Disease Control and Prevention, and the U.S. Food & Drug Administration are all good sources of information on the history, prevalence and side-effects of PFAS. The fact these sites and many others dedicate considerable space to PFAS reflects the growing alarm.

According to the U.S. Food & Drug Administration, “PFAS are a diverse group of human-made chemicals used in a wide range of consumer and industrial products. PFAS do not easily break down and some types have been shown to accumulate in the environment and in our bodies. Exposure to some types of PFAS have been linked to serious health effects. . . . Although PFAS have been in use for more than 80 years, scientific understanding and technical instrumentation needed to test for PFAS at very low concentrations began only recently."

PFAS have been linked to cancer, weakened immune systems, fertility problems and more. In 2016, the EPA guidance set a PFAS limit of 70 parts per trillion in drinking water. The agency updated its guidance in 2022, and the new limit is 0.02 ppt. In other words, PFAS are considered so toxic that the EPA wants them as close to zero as possible. Further details can be found in an article from the Harvard University School of Public Health, here. ​

In the interest of public health and safety, Teledyne ISCO has developed best practices for sample collection for PFAS in water and wastewater.​​ This resource page introduces concepts, instructions, considerations, and solutions to provide a ​​quick, deep dive into how to safely and effectively gather samples for PFAS testing.​ 

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A How-To for Sampling Water & Wastewater to Detect PFAS

Per- and polyfluoroalkyl substances (PFAS) can be detected in trace amounts in water and wastewater, but obtaining an accurate assessment is a challenge due to the ubiquitous nature of the chemicals. Exacting steps must be taken before, during and after samples are obtained to ensure they are not compromised.

As experts in water and wastewater sampling and flowrate measurement for more than 60 years, Teledyne ISCO is uniquely qualified to assist in determining and implementing best practices that take much of the guesswork, wasted time, unnecessary expense and inaccurate analysis due to compromised samples out of the equation. Following is a high-level view of industry standards and best practices. For more detailed information specific to your application, feel free to contact our Water Product Support team at [email protected] or in the United States, toll-free at 866-209-6174.

It is important to note that this is a rapidly evolving science, and these pages will be updated as the subject evolves.

Equipment Choices/Material Selection

PFAS sampling is conducted in much the same way as any sampling project; however, extreme care must be taken before, during and after collection to maintain the integrity of the samples. Due to the extreme prevalence of PFAS in our environments and the extremely small quantitative measurements (0.02 ppt) in the EPA guidelines, the potential for cross-contamination is significant. Therefore, far greater care is required to avoid compromising the quality of the collected sample. For example, it is recommended to wear powderless nitrile gloves when working with and around the sampling field.

You must consider not only the materials that will come into direct contact with the sample, but also those materials that will be present in a wide swath of the sample collection area — including those worn and used by the sample technicians. Anecdotally, one entity instructs field personnel to not wash or shampoo the day before they are deploying equipment or collecting PFAS samples due to the cross-contamination potential from soaps, toiletries and hair care products. Again, keep in mind that with PFAS, we are looking for detection in the parts per trillion range, so the potential for significant cross-contamination is very real.

Sources of contamination

Avoid the following before and during sampling or while at the sampling site. While not an exhaustive list, these points again demonstrate the prevalence of PFAS and the care that must be taken.

Please note: PPE could contain PFAS. However, never compromise safety for the sake of eliminating PFAS material. If there is no equivalent PFAS-free option available, document the use of such and use a blank sample​ to establish a baseline presence of PFAS with the equipment and the exposure potential.

  • Personal sources of contamination: soaps, shampoos, insect repellants, sunscreen, moisturizing lotion, cosmetics, some toothpastes
  • Clothing that was washed using fabric softeners
  • Clothing and textiles marked stain-resistant or waterproof, including raincoats and footwear, rugs and furniture
  • Fast food containers/packaging, food or drink in sealed packages (e.g., juice boxes)
  • Materials that are NOT in direct contact with the sample but should be avoided include but are not limited to: GPS receivers, notebooks, clipboards, etc. they could have PFAS on their surfaces and become a source of contamination!

Materials to use or avoid in sampler parts

At the top of the list of materials that must be avoided, DO NOT USE PTFE or FEP tubing or any tubing that contains fluoride for suction line or any part of the sampler equipment. Generally speaking, high-density polyethylene (HDPE) sample collection bottles should be used. Low-density polyethylene (LDPE) that has NOT been verified to be PFAS free should NOT be used. Sample collection bottles should be used sparingly for PFAS sampling and then discarded due to the minute trace amounts under consideration.

Approved Materials

  • Strainer: stainless steel or stainless steel/HDPE
  • Tubing coupler and bulkhead fitting: stainless steel
  • Suction line: vinyl
  • Pump tubing: silicone (See the Teledyne ISCO poster: P​FAS Applications-Study on Tubing)
  • Collection bottles: HDPE or polypropylene (PP)
  • Natural Ice from verified PFAS-free water

Materials to avoid or use with caution

  • LDPE (unless tested and verified to be PFAS free)
  • Glass (unless tested and verified to be PFAS free). Samples should not be stored in glass for an extended period, as it can absorb PFAS over time and contribute to cross-contamination. Limit the re-use of glass for this reason.
  • Teflon or related materials
  • Items or materials containing any fluoropolymer
  • Gel-Paks

Equipment considerations

  • Sampling equipment used for PFAS sampling should be dedicated to and ONLY used for PFAS sampling.  With the trace amounts of PFAS we are looking for, we don't want to have cross-contamination from the equipment used for other purposes.
  • Decontamination is a MUST due to the sensitive nature and cross-contamination threat. This is often accomplished with a thorough rinse with known PFAS-free water being run through the sample lines.
  • It is recommended that you communicate with your analytical laboratory and appropriate regulatory agency for their specific decontamination recommendations.​
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​G​​rab samples open the door to all variances that can impact the integrity of the collected sample. Grab samples also increase the risk of cross-contamination due to the direct human contact with the act of collecting the sample. Automated sampling results in consistent samples and eliminates variances that can impact sample integrity.​​

​Auto​matic Sampler Factors

Composite sampling is most common. Time-paced is common but there are those who flow-pace as well, assuming there is a flowmeter in place to perform that function.


Prepare three equipment blanks in the lab (1. ​Equipment Rinse Blank, 2. Field Blank, 3. Trip Blank) before going to the site and after sample collection using deionized water that has been validated to be PFAS free. Taking equipment blanks for analysis is a frequent and standard procedure to ensure sampling components are not contributing to false readings and elevated detection of PFAS. Click here to find details on equipment cleansing and taking blanks

Programming approaches

  • Could one day be regulatory driven, but currently, normal approaches for programming are acceptable.
  • Time Paced: common is one sample every 15 minutes for 24 hours
  • Flow Paced: It is common to design a program that will collect 96 samples based upon average daily flow volume over 24 hours; however, ensure your configuration choices leave room for additional samples during an above average flow day.  (Note: Flow pacing is not suitable for applications that have a wide range of daily volumes.)

The future: Regulatory Considerations

Going forward, the EPA anticipates developing guidelines for additional PFAS or categories of PFAS as the agency publishes toxicity assessments. Regulations could occur at the federal, state or local level. While the 0.02 part-per-trillion is a guideline, not a regulation, the minute amount stated in the guidelines suggests that should regulations be put in place, those rules would be stringent, and remediation could come at a considerable cost.

Again, although PFAS have been around since the 1940s, knowledge of the impact of PFAS on the environment and personal health is in its infancy. The same can be said for detection and remediation principles. As the subject evolves, these pages will be updated to reflect those changes. ​

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​​Accurate PFAS sampling requires specific materials that do not add PFASs to samples or absorb it from them. Teledyne ISCO has produced a kit to make PFAS sampling easy. Materials in each item of the kit have been selected based on United States guidelines to avoid adding or absorbing PFASs. The Kit includes Category 1 items that comes directly in contact with samples, such as strainer, suction line, pump tube, bottles to prepare blanks, and sampler collector. The Kit also includes some of Category 2 items that do not come in contact with sample, but used in sampling process.​​

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