Septic Surprises
Identifying the Impacts and Potential PFAS Risks of Septic Systems
A property can look squeaky clean on paper: no factories, no tanks, no “chemical” history. But if you don’t ask, “Is it on septic?” you may overlook one of the most surprising, and potentially most significant, sources of PFAS.
Often minimized in environmental assessments, septic systems have emerged as a pathway for PFAS to infiltrate groundwater. While septic systems don’t generate PFAS, they collect the chemicals from everyday products washed down drains, including soaps, detergents, shampoos, cosmetics, cleaners, fabric treatments, and more. Over time, this accumulation can become a potent source of contamination.
When a septic system is present on a site, Langan’s PFAS team evaluates site history, current operations, and wastewater characteristics, along with local geology, hydrogeology, and evolving regulations, to determine whether the system could serve as an ongoing source. This type of assessment helps project teams understand whether sampling is warranted, how potential PFAS impacts may affect site value or liability, and what steps may be needed to stay ahead of regulatory expectations.
Recent studies from Massachusetts and New Hampshire confirm the legitimacy of septic-system-related concerns. A 2021 study in Cape Cod found PFAS in domestic drinking water wells, with evidence pointing to septic wastewater as a key culprit. Additionally, the New Hampshire Department of Environmental Services (NHDES) uncovered the widespread presence of PFAS in groundwater in 2024, attributable not only to typical sources like air force bases, plastics manufacturers, and waste sites, but also to septic systems. The NHDES study also noted that septic systems can act as PFAS “reservoirs,” amassing concentrations that surpass regulatory limits and slowly releasing them into the environment. Because these compounds are remarkably persistent, an “unassuming” residential or commercial property can be a haven for contamination.
However, this issue is not limited to New England. Septic systems serve approximately 25% of the U.S. population, and studies in Wisconsin (2023) and Michigan (2025) also link household septic discharges to PFAS found in shallow groundwater. Regardless of location, PFAS and PFOA thresholds are extremely low, and federal actions (e.g., EPA drinking-water rule; CERCLA hazardous-substance designation for PFOA and PFOS) raise the stakes around investigation, disclosure, and allocation of responsibility.
While these discoveries may feel overwhelming, Langan understands the importance of an informed diligence approach—and knows the right questions to ask upfront. By proactively gathering information about potential PFAS impacts, the team can translate site conditions into practical risk, develop tailored sampling strategies, and help clients make informed decisions.
When it comes to potential PFAS impacts, septic is no longer a footnote—it’s a potential liability. Yet with the right guidance, a “septic surprise” becomes a manageable diligence item rather than a late-stage liability.
Jamie Barr, LEP, is a Principal in Langan’s New Haven office and leader of the firm’s environmental engineering and hazardous building materials practice in New England. His expertise covers brownfield redevelopment, Transfer Act compliance, remediation system design, and environmental site assessments. Barr specializes in evaluating the redevelopment potential of complex, contaminated properties nationwide, with a focus on innovative closure strategies, regulatory negotiations, permitting, public engagement, feasibility analyses, and due diligence.
Kristen Wexler, CHMM, is an environmental professional whose focus includes brownfield redevelopment, site characterization, and remediation in New York and Connecticut. Her areas of expertise include due diligence, real estate development, site characterizations, remedial investigations, remedial strategies and designs, and remedial-action implementation and management.
William Adsit, EIT, is experienced in environmental consulting with a primary focus on site characterization and remediation in Connecticut and surrounding New England states. His areas of expertise include environmental due diligence, environmental field investigations (soil, groundwater, and soil vapor), remedial design and field oversight, tank removals, and various Connecticut-specific environmental compliance areas, most notably Aquifer Protection Areas.