Designing Resilient PFAS Treatment Strategies For Water Agencies
By Bob Cipolletti
Water agencies across the U.S. are facing a rapidly evolving regulatory landscape for per- and polyfluoroalkyl substances (PFAS) that poses a conundrum: Should they take a cautious or aggressive approach to treating PFAS contamination in their water system?
Only two compounds — PFOS and PFOA — are currently regulated under maximum contaminant levels (MCLs), but with thousands of additional chemicals under scrutiny, utilities must prepare for a future where standards tighten and new contaminants are added to the list.
In Florida, the state’s recent adoption of EPA drinking water standards has brought these challenges into sharp focus for utilities, highlighting the need for treatment strategies that are both resilient and adaptable to treat and remove these “forever chemicals” from the water supply.
Funding Realities
One of the most pressing issues for water utilities is the limited availability of funding for PFAS upgrades. Recent settlement funds totaling more than $14 billion were awarded to public water systems and municipalities as a result of major legal settlements with several industrial chemical manufacturers, which are helping agencies address their immediate needs.
But future regulatory changes will likely require additional investments — costs that ultimately fall on ratepayers.
With a tight budget for expensive remediation, combined with uncertainty surrounding what levels of PFAS removal will be necessary, some agencies are taking a more patient approach to their efforts, awaiting more concrete rulings on EPA standards.
It’s understandable, considering some municipalities that took a proactive approach now face the possibility that they’ll still have to do more.
The experience of Harrisburg, Pennsylvania, serves as a cautionary tale. Like many U.S. cities, Harrisburg invested in water treatment upgrades to comply with the EPA’s PFAS standards in effect at the time. These upgrades were designed to meet the then-current MCLs for PFOS and PFOA, the two most commonly regulated PFAS compounds.
In 2023, Pennsylvania set its own PFAS MCLs: 14 parts per trillion (ppt) for PFOA and 18 ppt for PFOS, which Harrisburg used as the guide for its upgrades. Shortly afterward, the EPA finalized even stricter federal MCLs: 4 ppt for both PFOA and PFOS, effective nationwide by 2029. This meant that systems like Harrisburg’s, which had just completed upgrades that only met the state’s higher limits, would once again be out of compliance with the new, stricter federal standards. They will be required to plan for additional, potentially expensive retrofits, having already exhausted available settlement funds or grants on the initial upgrades.
This scenario is not unique to Harrisburg. Across Pennsylvania, nearly 19% of water systems tested in early 2024 exceeded the new EPA PFAS standards, even though they may have been compliant under previous state rules.
This illustrates the risk of designing water treatment systems to meet only current standards, rather than anticipating future regulatory tightening.
Scenario Planning And Decision Analytics
To avoid these situations, utilities are encouraged to use scenario planning and modular system designs to avoid repeated, costly retrofits as standards evolve.
To navigate these complexities, agencies can adopt a scenario-based decision framework that considers probability, impact and cost. Drawing on prior experience, combined with best practices in the industry and realistic estimates of anticipated standards, utilities can use decision analytics tools to rank scenarios and guide investment.
The goal is to avoid “high-highs”— situations with both high probability and high impact — by making design choices that reduce risk. Agencies should also monitor low-probability, high-impact scenarios and pre-wire expansion options to act quickly if needed.
The Regulatory Context: Why Florida Matters
Florida’s approach to PFAS regulation has been notably cautious. Unlike early movers such as California, New Jersey, and Michigan — states that set aggressive standards and moved quickly to implement treatment — Florida waited for federal guidance before acting.
This strategy helped avoid some pitfalls experienced elsewhere, such as investing in systems that quickly became obsolete when standards changed. Now, with EPA standards in place, nearly all Florida water supplies have been sampled and found to be impacted by PFAS, creating an urgent need for action.
Florida’s comprehensive sampling effort has revealed widespread PFAS impacts, underscoring the need for coordinated action and knowledge sharing among utilities.
With PFAS detected in the water supply, New Smyrna Beach is one city that now faces the challenge of designing a treatment system that meets current MCLs while allowing for future expansion. Modular design and scenario planning are key to ensuring compliance as standards evolve.
The issue of biosolids disposal after PFAS treatment is a major concern in Miami-Dade County, with procurement decisions pending. Agencies must consider not only how to remove PFAS but also what to do with the residuals.
Design Principles For Future-Proof Treatment
Given these uncertainties, water agencies should prioritize modularity and expandability in their treatment systems. By engineering treatment trains that can accommodate additional PFAS species — or even microplastics — utilities can minimize disruption and control disposal costs when new regulations emerge.
For example, when I worked on creation of a de-icing system at Seattle-Tacoma International Airport, the area was identified as being vulnerable to PFAS fouling. Early design adjustments helped obviate this risk, even before local PFAS data was available. Now future-proofed to forthcoming standards, the airport also became an environmental steward, providing added protections to the region’s water supply.
The transition to fluorine-free foam (F3) is another area where careful planning is essential. Waste streams from F3 are limited to a small set of “least-bad” options, and agencies must weigh these choices against cost and liability considerations.
Stormwater sampling regulations are also evolving, with aviation and power clients expressing concerns about PFAS testing both in Florida and nationally.
Following an implementation roadmap will help guide the process:
- Near-term compliance: Focus on meeting current PFOS/PFOA MCLs using available funding and proven technologies.
- Medium-term expandability: Design systems with modular components that can be upgraded as new PFAS compounds are regulated.
- Long-term resilience: Invest in scenario planning and decision analytics to anticipate future regulatory changes and minimize retrofit costs.
Microplastics: The Next Frontier
While PFAS is the immediate concern, microplastics are increasingly commingled in regulatory discussions. Agencies should acknowledge this overlap and prepare to integrate microplastics treatment into future upgrades as regulations emerge.
By designing treatment systems that are modular, expandable and informed by scenario planning, utilities can reduce the risk of costly retrofits and ensure a sustainable, PFAS-free water supply for their customers. As regulations continue to evolve, proactive planning and collaboration will be essential to meeting both current and future challenges.
Bob Cipolletti is Senior Vice President and Geologist for WSP in the U.S.