WSSC Restarts Bidding on a PFAS Pilot at the Potomac Plant as It Plans $298 Million in Treatment

WSSC Water is restarting its search for a company to design, build and run a pilot plant at its Potomac Water Filtration Plant to test treatment for PFAS, the long-lasting chemicals often called “forever chemicals,” along with other water quality targets. Separately, WSSC’s capital plan includes a PFAS treatment program budgeted at $297.86 million, funded with WSSC bonds, which are repaid mainly through water and sewer charges.

WSSC’s water currently meets the new federal PFAS standard, and no violation has occurred. The standard for PFOA and PFOS, two of the most widely regulated of the chemicals, is 4.0 parts per trillion each, measured as a running average of quarterly samples, and it cannot be enforced until April 26, 2029, under the federal rule. Under that rule, any PFOA or PFOS result below 4.0 counts as zero in the average. By that method, WSSC’s published averages as of August 2026 are 1.3 parts per trillion for PFOS at the Potomac plant and zero for every other regulated PFAS at both plants. The Potomac plant’s measured results are not zero: over the last four quarters, PFOA ranged from 1.9 to 3.0 parts per trillion, and measured PFOS averaged 2.9. Both are below 4.0.

One recent sample was higher. In July 2026, treated water from the Potomac plant measured 5.1 parts per trillion of PFOS, according to WSSC’s third-quarter results. That is not a violation, because the limit applies only to the yearly average, not to single samples. It was the highest Potomac PFOS reading in WSSC’s posted results since September 2022, when a sample measured 6.2. A May 2025 sample measured 4.2.

What the $297.86 million is for

The program’s project sheet, dated October 1, 2025, in WSSC’s adopted capital plan listed it as 0% complete, with an estimated completion of June 2032. Most of the money comes late: $257 million of the total is scheduled for fiscal 2030 through 2032, including $135.8 million in fiscal 2032. The estimate grew from an initial $256.5 million to $297.86 million. The sheet’s cost-change section reads “Not applicable,” and it says the present scope “was developed for the FY’27 CIP.”

The sheet explains why WSSC is planning treatment for levels that currently comply: “For both source waters, levels are below PFAS MCLs and would be in compliance with the new regulation. However, future compliance is not guaranteed, due to factors such as vast numbers of potential and unknown sources of PFAS in the watershed, potential variability of PFAS levels in the source water, and the changing nature of water quality due to climate change.”

It also says the first phase will be partial: “Based on high treatment cost and current levels below the PFAS limits, the project will start by sizing a PFAS treatment system for a portion of the Potomac Water Filtration Plant’s capacity, with the view to scale up treatment capacity if needed.”

WSSC has proposed less for the program next year than its adopted plan scheduled. The adopted plan scheduled $14.1 million for the program in fiscal 2028. WSSC’s proposed fiscal 2028 capital budget lists $6.17 million.

A pilot aimed at half the federal limit

In its first solicitation for the pilot, WSSC set a target of 2 parts per trillion, half the federal limit. In written answers to prospective bidders, WSSC said “the target limit for PFOA/PFOS is 2 ppt” and that the target “is applicable to PFOA and PFOS individually, not the combined concentration.” WSSC also said it is working on reducing PFAS at the source, in the watershed, separately from the pilot. The reissued solicitation keeps that target: its scope of work again lists a performance target of “2 ppt” for PFAS. The scope also says average PFAS in WSSC’s treated water is “around 2 – 3 ppt for PFOA and PFOS (0 ppt by compliance calculations).”

WSSC first sought a firm in June. That solicitation was later canceled with a one-line notice: “Pursuant to the WSSC Procurement Regs, it has deemed it in the best interests of WSSC to cancel.” The notice gave no further explanation. It reissued the solicitation on October 14, with changes to how proposals will be scored and a new key team role, a process engineering manager, whose experience designing treatment for PFAS and other contaminants will be scored. A non-mandatory pre-bid meeting and site visit were scheduled for October 21 at the plant on River Road, and proposals are due December 1.

The federal and state rules are still moving

EPA has proposed letting eligible water systems that ask for it have two more years, until April 26, 2031, to meet the PFOA and PFOS limits. The proposal would apply in states that have not yet taken over enforcement of the PFAS rule, which for now includes Maryland. As of this week, it remains a proposal. Separately, in January a federal appeals court denied a motion to throw out the rule’s limits on four other PFAS without a full ruling, a motion that was EPA’s, according to an article by CMBG3 Law attorneys published in the National Law Review, and the court heard arguments in the challenge to the rule in September.

In Maryland, the Department of the Environment has sent the General Assembly’s regulation review committee a proposal to adopt state PFAS drinking water standards “identical to federal regulations,” according to the committee’s September summary. Adopting the rule is a step toward the state taking over its enforcement.

The same plant that lost power

The Potomac plant is the larger of WSSC’s two plants and serves about 70% to 75% of its customers. It is the same plant that lost power on September 29, when WSSC asked all of its customers to use water only for essential purposes. On October 22, we reported that WSSC’s own Commission materials list $155 million in electrical upgrades needed at the plant.

Still unanswered

• Why WSSC canceled the first solicitation, and whether the pilot will be paid for from the $297.86 million program.
• Why the cost estimate rose by $41.4 million, and whether the June 2032 completion date still holds.
• What WSSC’s separate effort to reduce PFAS at the source involves.

PFAS results are in parts per trillion. Under the federal rule, a PFOA or PFOS result below 4.0 parts per trillion counts as zero when calculating the running annual average, which is how WSSC calculates its published averages. We have not yet put these questions to WSSC; this story will be updated with any response.

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