Per- and polyfluoroalkyl substances (PFAS) are a large family of synthetic chemicals manufactured and used since the 1940s. They are often called “forever chemicals” because their exceptionally strong carbon-fluorine bonds make them highly resistant to environmental degradation. PFAS have been used to create products resistant to heat, oil, stains, and water, appearing in items from non-stick cookware to firefighting foams. Because they are highly mobile and do not break down easily, PFAS can contaminate drinking water sources. Testing your water is the only way to determine if these contaminants are present in your home’s supply.
Choosing the Right Testing Approach
Reliable water testing requires choosing between consumer-grade screening and professional laboratory analysis. While simple, in-home test kits exist, they present significant limitations for actionable data. Some home kits only screen for total organic fluorine, which indicates the presence of PFAS but cannot identify specific compounds or their exact concentration. This lack of specificity means the results are non-actionable in a regulatory context.
Reliable testing demands the precision of a certified environmental laboratory. These professional facilities use specialized, highly sensitive equipment and standardized protocols to measure individual PFAS compounds. The resulting data is legally defensible and accurate, even at the extremely low concentrations relevant to health guidelines. For testing intended to inform health decisions, guide filtration purchases, or pursue legal action, a laboratory analysis is necessary.
The Certified Laboratory Testing Process
The testing process begins by selecting a laboratory with recognized certifications for PFAS analysis in drinking water. Look for facilities certified by your state or accredited by programs like the Department of Defense Environmental Laboratory Accreditation Program (DoD ELAP) or ISO 17025. Once chosen, you typically purchase a testing kit directly from the lab, which includes all necessary sample bottles and detailed instructions.
The sample collection process is highly sensitive to cross-contamination because PFAS are ubiquitous in consumer products. The kit contains specially prepared, preserved bottles that must not be rinsed or contaminated by household items. It is essential to avoid using personal care products, such as hand creams or cosmetics, and wearing water-resistant clothing before and during sampling. Samples are collected from the tap following specific flow instructions, then immediately sealed and placed in a cooler with ice to maintain the chemical preservatives.
The final steps involve completing the chain-of-custody form, which documents every transfer of the sample to ensure data validity. The sample must be shipped back promptly, often via overnight shipping, to meet the required holding times for the preservatives. Laboratories verify the sample temperature and integrity upon receipt before beginning the analysis.
Understanding Analytical Methods and Detection Limits
Certified laboratories analyze water samples using precise, standardized methods developed by the Environmental Protection Agency (EPA). The two most commonly approved methods for drinking water are EPA Method 537.1 and EPA Method 533, which together measure up to 29 specific PFAS compounds. Both methods rely on liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS).
The LC/MS/MS process first separates the different PFAS compounds in the sample, and then the mass spectrometer detects and quantifies each one individually. Since PFAS are regulated at extremely low levels, the Method Detection Limit (MDL) is important. The MDL is the lowest concentration a laboratory can reliably detect, often measured in parts per trillion (ppt), equivalent to nanograms per liter (ng/L).
The Method Reporting Limit (MRL) is the lowest concentration at which the lab can accurately quantify and report the result. For compliance testing, these limits are often set below 2 ppt to ensure trace amounts of contaminants are captured. If a compound is present below the MRL, the lab indicates it was not detected or detected below the reporting limit, meaning the concentration is too low to be precisely measured.
Interpreting Test Results and Safety Guidelines
Interpreting the numerical results requires understanding the current regulatory framework for these contaminants. The EPA has established enforceable Maximum Contaminant Levels (MCLs) for six individual PFAS, including PFOA and PFOS, set at 4 parts per trillion (ppt). These MCLs are the legally allowable maximum concentrations in public drinking water systems, applying only to public utilities, not private wells.
The EPA also establishes Maximum Contaminant Level Goals (MCLGs), which are non-enforceable health goals. These goals are set at the level where no known health risk is expected; for PFOA and PFOS, the MCLG is zero, signaling the agency’s position on their potential toxicity. Many states have established their own enforceable MCLs or health advisories that may be more stringent than the federal standards.
If your results show PFAS levels above the federal MCLs or state guidelines, action is necessary to reduce exposure. The two most effective point-of-use treatment methods for removing PFAS are granular activated carbon (GAC) filters and reverse osmosis (RO) systems. Contacting your local health department or a water treatment professional can help determine the best filtration system for your home and the specific contaminants found in your water.