PFAS Due Diligence in Houston, Delaware, and the Mid-Atlantic

PFAS are no longer an abstract “emerging contaminant” issue. They are now part of real estate due diligence, industrial compliance, water-supply planning, environmental investigations, and long-term liability evaluation.

Per- and polyfluoroalkyl substances, commonly referred to as PFAS, are a large group of synthetic chemicals that have been used for decades in industrial processes, firefighting foams, coatings, textiles, packaging, nonstick products, and other applications. They are persistent, mobile in groundwater, and difficult to destroy using conventional treatment methods. That combination has made PFAS one of the most important environmental issues facing property owners, developers, municipalities, industrial operators, and lenders.

For companies working in Texas, Delaware, and the broader Mid-Atlantic region, PFAS risk is not the same everywhere. The sources, pathways, regulatory context, and business implications can vary significantly by geography and site history.

Why PFAS Matters in Environmental Due Diligence

PFAS can affect a site even when there is no obvious spill, drum storage area, or historical release on the property. Because PFAS have been used in many products and industrial processes, they may be associated with manufacturing, fire training, wastewater treatment, landfills, plating operations, airports, military facilities, refineries, chemical plants, textile or paper coating operations, and areas where biosolids or wastewater residuals have been managed.

That creates a due diligence challenge. PFAS risk is often not visible during a site reconnaissance, and historical records may not clearly identify PFAS use. A property may have a relatively clean environmental history for traditional contaminants but still warrant PFAS consideration based on surrounding land use, water-supply vulnerability, waste handling, fire suppression history, or regional groundwater conditions.

A technically sound PFAS review asks a practical question:

Is there a reasonable basis to suspect PFAS may be present at or near this property, and could that affect the transaction, redevelopment, water supply, regulatory strategy, or long-term liability?

Houston-Area PFAS Drivers

In the Greater Houston area, PFAS risk is closely tied to the region’s industrial and infrastructure footprint. Houston’s economy includes refining, petrochemical manufacturing, oil and gas support services, airports, ports, rail-served industrial corridors, fire training facilities, landfills, wastewater treatment plants, and a wide range of heavy commercial and industrial operations.

Common PFAS source considerations in the Houston area include:

• Firefighting foam and fire training areas, particularly where aqueous film-forming foam, or AFFF, may have been used for fuel fires, emergency response, industrial fire protection, airport operations, refinery response, or training activities;

• Oil and gas and petrochemical operations, including facilities where PFAS may have been used in specialized industrial applications, fire suppression systems, surfactants, coatings, or chemical processing;

• Industrial manufacturing and chemical handling, especially where fluorinated chemicals, surface treatments, coatings, plating, or specialty chemical processes may have been used;

• Airports, ports, rail yards, and logistics facilities, where fire response, fuel handling, maintenance, and industrial operations may overlap;

• Wastewater treatment plants and biosolids, because PFAS from commercial, industrial, and household sources can pass through wastewater systems and concentrate in residuals;

• Landfills and waste management facilities, where PFAS-containing consumer products, industrial waste, sludge, or treatment residuals may have been disposed;

• Adjacent or upgradient industrial properties, especially in areas with shallow groundwater or complex historical land use.

  
  

Houston Public Works’ PFAS FAQ identifies fire training/fire response sites, industrial sites, landfills, and wastewater treatment plants/biosolids as major PFAS source categories, which aligns closely with the types of facilities commonly encountered in Houston-area due diligence.

For Houston properties, PFAS evaluation should not be limited to whether the subject property itself manufactured PFAS. The more common question is whether site history, surrounding land use, groundwater conditions, fire protection history, or waste-management practices create a plausible PFAS concern.

Delaware and Mid-Atlantic PFAS Drivers

In Delaware and the broader Mid-Atlantic region, PFAS risk has a somewhat different profile. Firefighting foam remains an important potential release scenario, but manufacturing and chemical production history are often more central to the regional PFAS story.

Delaware has a long industrial and chemical manufacturing legacy, including companies historically associated with PFAS-related production, use, or liability. The State of Delaware entered into a PFAS-related settlement with DuPont, Chemours, Corteva, and related entities in 2021 to fund PFAS testing, sampling, analysis, and remediation-related work.

Common PFAS source considerations in Delaware and the Mid-Atlantic include:

• Chemical manufacturing and specialty chemical production, including facilities that made, processed, or used fluorinated compounds;

• Manufacturing of PFAS-containing products, including coatings, films, textiles, paper treatments, packaging, sealants, and specialty materials;

• AFFF use at airports, military installations, refineries, ports, fire training centers, and emergency response facilities;

• Industrial wastewater discharges, including discharges to publicly owned treatment works or surface water;

• Wastewater treatment plants, sludge, and biosolids, especially where industrial or mixed municipal waste streams may have contributed PFAS;

• Landfills and disposal facilities, including facilities that received industrial wastes, consumer products, treatment residuals, or contaminated soils;

• Plating, metal finishing, and surface treatment operations, where PFAS-containing mist suppressants or surfactants may have been used;

• Textile, carpet, leather, paper, and packaging operations, where stain-resistant, water-resistant, or grease-resistant treatments may have been used;

• Drinking water supply areas and private wells, particularly where groundwater is vulnerable or where PFAS sources are located upgradient.

  
  

In Delaware, the PFAS issue is not only about individual source properties. It is also about regional water resources, historical manufacturing corridors, groundwater migration, and the relationship between legacy industrial activity and public or private water supplies.

PFAS Is a Source, Pathway, and Receptor Problem

A strong PFAS evaluation should not stop at identifying a potential source. It should consider the full conceptual site model:

Source: Where could PFAS have been used, released, discharged, disposed, or applied?

Pathway: How could PFAS move through soil, groundwater, surface water, stormwater, wastewater, air deposition, or biosolids?

Receptor: Who or what could be affected — public water systems, private wells, construction workers, surface water, ecological receptors, future residents, or downstream properties?

This matters because PFAS are highly persistent and some compounds are mobile in groundwater. A release at one property may become a concern for downgradient properties, drinking water wells, surface water, or redevelopment sites. Conversely, PFAS detected on a property may originate from an off-site source, a regional groundwater plume, wastewater residuals, or historical fill.

For due diligence, that distinction is critical. The question is not simply whether PFAS are present. The question is whether PFAS are present at levels and locations that create a material risk for the transaction, site use, water supply, regulatory strategy, or construction plan.

Regulatory Context Is Moving Quickly

PFAS regulation is evolving rapidly. In April 2024, EPA finalized the first national drinking water regulation for several PFAS compounds, including enforceable Maximum Contaminant Levels for PFOA and PFOS at 4 parts per trillion, with additional limits for PFHxS, PFNA, HFPO-DA, and certain PFAS mixtures.

EPA has since announced proposed changes to parts of that drinking water framework. As of May 2026, EPA has proposed maintaining the PFOA and PFOS drinking water standards while allowing additional implementation time for some water systems, and separately proposed rescinding and reconsidering certain regulatory determinations and standards for PFHxS, PFNA, HFPO-DA, and the Hazard Index mixture standard.

That regulatory movement does not make PFAS less important. It makes PFAS due diligence more important. Buyers, sellers, lenders, developers, municipalities, and industrial operators need to understand that PFAS risk may be affected by federal rules, state programs, drinking water requirements, litigation, cleanup standards, disposal limitations, and evolving expectations from insurers and lenders.

Delaware has also been actively addressing PFAS in drinking water and implementation planning. DNREC notes that public water systems are required to report PFAS monitoring results in Consumer Confidence Reports beginning with the 2027 report, and Delaware’s PFAS implementation planning has tracked the federal drinking water standards and compliance framework.

Where PFAS Shows Up in Real Estate and Development

PFAS can affect real estate and development in several ways.

For a buyer, PFAS may affect environmental liability, purchase negotiations, lender requirements, or post-closing obligations.

For a seller, PFAS may become an issue during due diligence if the property history includes fire training, industrial operations, chemical handling, wastewater discharges, or waste disposal.

For a developer, PFAS may affect soil management, dewatering, groundwater discharge, stormwater management, utility installation, or the suitability of certain end uses.

For municipalities and water providers, PFAS can affect treatment requirements, monitoring, public communication, and long-term capital planning.

For industrial operators, PFAS may affect wastewater permits, waste characterization, product stewardship, fire suppression systems, and future compliance planning.

In many cases, PFAS is not the only environmental issue at a site. It may overlap with petroleum hydrocarbons, chlorinated solvents, metals, PCBs, asbestos, pesticides, or other legacy contaminants. The due diligence strategy should account for that reality rather than treating PFAS as a standalone issue.

When Should PFAS Be Considered in a Phase I ESA?

A Phase I ESA does not automatically include PFAS sampling. However, PFAS should be considered during the historical review, regulatory review, site reconnaissance, and interviews when the property or surrounding area includes uses commonly associated with PFAS.

Examples include:

• Current or former fire training areas;

• Airports or aviation facilities;

• Refineries, terminals, or fuel-handling facilities;

• Chemical plants, coating operations, plating facilities, or specialty manufacturing;

• Landfills, wastewater treatment plants, or sludge/biosolids management areas;

• Military or defense-related facilities;

• Textile, paper, packaging, or surface-treatment operations;

• Sites with private wells or sensitive groundwater receptors;

• Properties located downgradient of known or suspected PFAS sources.

  
  

The Phase I ESA should not overstate PFAS risk where there is no reasonable basis for concern. But it should also avoid ignoring PFAS when the site history clearly suggests that further evaluation may be warranted.

What a Focused PFAS Review Should Include

A practical PFAS review does not need to start with broad, expensive sampling at every site. It should begin with a focused evaluation of likely sources, pathways, receptors, and business risk.

A strong initial PFAS review may include:

• Review of historical site use and surrounding land use;

• Evaluation of fire training, fire suppression, and AFFF use history;

• Review of industrial processes, chemical storage, wastewater discharges, and waste streams;

• Review of nearby public water supply data, private well concerns, or known PFAS detections;

• Evaluation of groundwater flow direction and potential off-site sources;

• Identification of regulatory, transactional, and redevelopment implications;

• Recommendation of whether PFAS sampling is warranted and, if so, which media should be sampled.

  
  

If sampling is appropriate, the scope should be targeted. Depending on the site, that may include drinking water, groundwater, soil, surface water, stormwater, sediment, wastewater, leachate, or biosolids. The selected analytical method, reporting limits, sampling procedures, and quality control measures matter because PFAS sampling is sensitive to cross-contamination and low detection levels.

Houston and Delaware Require Different PFAS Questions

A Houston-area industrial site may require questions such as:

• Was AFFF used for fire training or emergency response?

• Is the property near refineries, terminals, airports, landfills, wastewater facilities, or industrial corridors?

• Were fluorinated surfactants, coatings, plating chemicals, or specialty chemical products used?

• Could shallow groundwater, stormwater, or dewatering create a migration or discharge concern?

• Are nearby properties or water-supply receptors potentially affected?

  
  

A Delaware or Mid-Atlantic site may require questions such as:

• Was the property associated with chemical manufacturing, product manufacturing, or PFAS-containing materials?

• Is the site near known PFAS-affected areas, manufacturing corridors, airports, military facilities, or fire training areas?

• Could historical industrial wastewater discharges or residuals have affected soil, groundwater, surface water, or public water supplies?

• Are private wells, community water systems, or sensitive groundwater resources nearby?

• Has the property been affected by regional PFAS investigations, state-led sampling, or settlement-funded response actions?

  
  

The technical framework is similar, but the local source history matters.

The Bottom Line

PFAS due diligence is no longer optional for many industrial, commercial, municipal, and redevelopment sites. The issue is too widespread, the regulatory landscape is too active, and the potential business consequences are too significant to ignore.

In Greater Houston, PFAS concerns are often tied to firefighting foam, oil and gas, petrochemical operations, industrial facilities, airports, landfills, and wastewater systems. In Delaware and the Mid-Atlantic, manufacturing history, chemical production, PFAS-containing products, AFFF use, water-supply vulnerability, and regional groundwater concerns are often central to the risk picture.

A good PFAS evaluation does not assume every site is contaminated. It also does not assume PFAS is irrelevant because it was not part of traditional due diligence. The right approach is targeted, technically sound, and tied to the specific property, surrounding land use, water resources, and client objectives.

For buyers, sellers, developers, lenders, municipalities, and industrial operators, the goal is straightforward: identify PFAS concerns early, understand whether they are material, and develop a practical path forward before they become a transaction, compliance, construction, or liability problem.