Why Florida Water & Wastewater Utilities Should Understand EPA's PFAS Laboratory Method

What is EPA Method 1633?

PLEASE NOTE: mentions of EPA Method 1633 within this article are mentions of EPA Method 1633A. EPA had published several variations on Method 1633 prior to publishing the "final" version in December of 2024 that is still used today, which is known officially as EPA Method 1633A. If your facility has legacy Method 1633 data, please reach out to your local FDEP district office to determine if it is still eligible to be used for compliance purposes with permit or enforcement limitations.

EPA Method 1633 is a laboratory analytical method developed by the US EPA for quantifying PFAS in varying environmental mediums.

Unlike the majority of standard water quality analyses, PFAS species are measured at incredibly low concentrations, most often in parts per trillion (ppt; equivalent to ng/L or nanograms per liter). To put these concentrations into perspective, one part per trillion is approximately equivalent to a single drop of water dispersed throughout twenty Olympic-sized swimming pools.

Because detecting contaminants at these concentrations is so difficult, Method 1633 requires extremely sensitive instrumentation, specialized laboratory procedures, and rigorous quality assurance practices to ensure that produced samples are both accurate and precise.

In terms of the actual laboratory procedures used to conduct Method 1633, liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is used to identify and quantify up to 40 individual PFAS compounds within a single sample. Both liquid chromatography and tandem mass spectrometry on their own are intensely challenging and labor-intensive analyses, and coupling them together to accurately quantify PFAS pushes these tests outside of the budget and capabilities of all but the most advanced of in-house utility laboratories.

Why was Method 1633 developed?

EPA Method 1633 was developed to fill gaps in the testing practices surrounding PFAS; most standardized PFAS methods were designed for relatively clean drinking water, and both wastewater effluent and biosolids tend to have higher concentrations of PFAS compared with processes and distributed potable water.

To put it in a way that some Florida water operators will love and others will hate: wastewater and biosolids are considerably more complex than drinking water.

Compared with drinking water, wastewater potentially contains significantly higher concentrations of the following:

Organic compounds
Biological solids
Industrial chemicals (surfactants, acids & bases, heavy metals, solvents, biocides)
FOG (fats, oils, & grease)
Inorganic suspended and dissolved solids

These materials interfere with laboratory analyses if not handled properly and can possibly lead to inconclusive or significantly elevated results compared to the actual concentrations in your sample.

EPA Method 1633 was specifically developed to overcome potential interference while providing reproducible results across multiple environmental matrices.

Which samples can be analyzed?

Method 1633's greatest advantage compared with more traditional PFAS testing methodology is its flexibility.

Possible matrices include:

Treated wastewater (effluent)
Raw wastewater (influent)
Biosolids
Waste and return activated sludge(s)
Surface water
Groundwater
Stormwater
Landfill leachate
Sediments & soils

For water utilities, the three matrices you will most likely be sampling with Method 1633 will be treated wastewater, raw wastewater, and biosolids. Public utilities in Florida will be required to sample their treated effluent and/or their biosolids a minimum of once a quarter starting July 1st of 2026 as a result of House Bill 1019 being signed into law. Click here to see our article on what Florida utilities need to know concerning HB-1019.

If budget allows, exploratory sampling within your collection system can assist your utility with understanding if there are any point-source dischargers of PFAS within your system. A one-off $1,000 Method 1633 sampling event feels like throwing away money, but targeted sampling can help you narrow down any violators of your pre-treatment program and make them take responsibility for prevention of their PFAS-laden discharge rather than allow your utility to shoulder the burden of treatment.

Why should Florida utilities care?

It seems like a common belief in the utility industry right now that PFAS came out of nowhere and that government agencies are scrambling to make your operations harder than they already are. It doesn't help that PFAS were seen as an emerging contaminant of concern talked about almost solely in academia for decades prior to becoming a mainstream worry – I only first learned about PFAS during an undergraduate course on emerging contaminants in early Covid (if you're reading this half a century from now, that means about 2020ish). At the time, it occupied a single lecture. Today, it has become a central topic across water treatment, toxicology, and environmental regulation, a clear reflection of how quickly the concern for PFAS has evolved. ...

2. How much experience does the laboratory have?

Laboratories are not required to publicly disclose how many times they've completed any analysis. Ask your lab directly how familiar they are with Method 1633 and how often their technicians are completing it. Ask them also if the test is something they're doing in-house, or if they're shipping your sample to a contract lab elsewhere.

It's important to remember that other members of the industry are some of your best resources, and that they are likely experiencing and completing the same sampling you have to. Reach out to other utilities before scheduling any work and see how their experience has been with a lab you're considering, what their samples and blank results came out to be (if they're comfortable sharing this information), and how confident they were with the laboratory's capabilities.

3. What matrices does the laboratory routinely analyze?

Some laboratories specialize primarily in drinking water while others may work only with hazardous waste sampling or other non-utility focussed methods. Verify that the laboratory is not only accredited to complete the analysis, but that it actually is an analysis they routinely complete. Would you rather a surgeon has completed an operation hundreds of times over multiple years, or once or twice in a blue moon before they operate on your family member? Why treat your utility's compliance sampling any different?

4. What are expected turnaround times?

The actual physical processes of completing a Method 1633 analysis takes 1 to 2 full days, but the average turnaround time to clients will depend on your laboratory. A well-staffed, well-equipped laboratory can expect a standard turnaround time of between 2 to 4 weeks on average. As of the writing of this article, Florida labs have been dealing with a sudden influx of orders due to recent regulatory changes: to be safe, an assumption of 4 to 8 weeks will likely find the turnaround time to fall within those ranges.

If your facility has specific regulatory deadlines for sampling results, it is recommended to sample as soon as possible within your specific sampling window. For instance, if your facility is required to sample once per quarter for PFAS AND has a strict deadline of the 28th day of the month following the end of your quarter, you should probably work with your staff and your laboratory to sample no later than the third week of the quarter – this allows you ample time to potentially resample if test results appear to be impacted by quality control failures ahead of submittal to your respective governing agency.

5. What quality assurance documentation is provided?

NELAP certified laboratories should be able to provide you with quality assurance (QA) documents following your sampling, or even potentially ahead of them depending on the documents needed.

These documents may include:

Laboratory Control Samples
Method Blanks
Matrix Spikes
Matrix Spike Duplicates
Laboratory Duplicates
Internal Standards
Surrogate Recoveries

Please note that the list above is a non-exhaustive list of potential QA documentation. Work with your utility's QA/QC officer or sampling lead to determine what documentation your facility might need.

Preventing sample contamination

The greatest challenge associated with sampling for PFAS is that PFAS are everywhere. "Everywhere" in this instance is meant literally. Scientific studies have shown that PFAS have been found in over 330 different wildlife species globally, the snowcaps of Mount Everest, within deep ocean trenches – even in pristine un-touched ice in Antarctica. Aside from being nearly ubiquitous within the environment, the actual sampling equipment your laboratory uses are almost guaranteed to have measurable quantities of PFAS on or in them.

A few of the common pathways for PFAS contamination during sampling is through contact with:

Waterproof clothing
Teflon products
Food packaging (think resealable plastic bags or fastfood wrappers)
Permanent markers
Certain adhesives
Personal care products
Some disposable gloves

Because PFAS are measured at parts per trillion, even slight contamination during sampling can heavily skew laboratory results and potentially place your facility out of compliance.

For this reason, utilities should carefully follow laboratory sampling instructions and avoid introducing unnecessary PFAS-containing materials during sample collection when conducting sampling on their own, and vet their laboratory's sampling staff should they arrange for sampling to be conducted by the lab.

Questions every utility should ask before sampling themselves

Before conducting your own PFAS sampling, consider asking your laboratory the following:

Which sample containers are required?
How should samples be preserved?
What holding times apply, if any?
Are field blanks recommended? (Note that Method 1633 does not explicitly require field blanks, but the EPA themselves strongly reccomend field blanks due to potential cross-contamination of samples.)
Does the laboratory provide sampling kits for Method 1633?
Which PFAS compounds are included in the analysis?
What is the laboratory's MDL (method detection limit)? (Laboratories have their own in-house MDLs for Method 1633 based on their specific instrument sensitivity, analyst performance, and regular statistical calculations. Because of this, the laboratory's MDL may not necessarily meet the level of precision required by regulation or permit/enforcement action for your utility.)
Does the laboratory routinely perform EPA Method 1633?

If you believe your utility is likely to move forward with a laboratory, but you're unsure if there's any questions left unanswered, click here for a free copy of Verley Environmental's PFAS Sampling Laboratory Selection Checklist.

The future of PFAS monitoring

PFAS regulation continues to evolve rapidly at both the federal and state levels, and Method 1633 is the primary method currently used for Florida compliance sampling for PFAS analysis in wastewater effluent and biosolids.

As additional monitoring requirements are implemented, EPA Method 1633 is expected to remain one of the primary analytical methods for wastewater and biosolids compliance monitoring.

Utilities that establish relationships with qualified laboratories today are in a much better position to make informed decisions in the future. For a broader look at why PFAS matter for Florida utilities in the first place, see our primer on PFAS and Florida water utilities, and for the state-level driver behind quarterly sampling, our breakdown of Florida HB1019.

Conclusions

EPA Method 1633 is quickly becoming one of the most recognized methods in the utility industry, one of the foundational tools used to characterize PFAS in a variety of matrices, and the only across-the-board approved method in both State and Federal regulation. Understanding what the method accomplishes, selecting experienced laboratories, and following proper sampling procedures can significantly improve data quality and help utilities prepare for Florida's evolving PFAS regulatory landscape.

Verley Environmental Perspective:

Vet your lab before you sample, not after. A single mishandled Method 1633 sample can put your facility on the wrong side of a compliance record for years. When in doubt, ask more questions than you think are necessary – reputable labs will welcome them.

TLDR

EPA Method 1633 is the only currently approved method for sampling PFAS in both wastewater effluent and biosolids and is an incredibly precise and difficult test to complete. Just because a laboratory holds a NELAP certification for Method 1633 doesn't mean they're your best choice to trust your analysis with.

Laboratories should be vetted prior to sampling. If sampling internally, staff should be particularly careful of cross contamination of field containers. Verley Environmental provides a free checklist of questions to ask before trusting a lab to run PFAS sampling for your utility.

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Citation information

Author(s): Jackson Verley
Date of Publication: July 3, 2026
Date of Last Edit: July 3, 2026
Title of the Page/Article: EPA Method 1633 Explained for Utilities
Website Name: Verley Environmental