By Gene Galin
Pittsboro, NC – Before water reaches a kitchen faucet in Pittsboro, it climbs from the Haw River to a treatment plant off U.S. 15-501, passes through a series of chemical and physical processes, and is tested and adjusted by operators who must respond to everything from muddy runoff to traces of industrial chemicals. On our Aug. 18 tour, water filtration administrator Cory Saulsbury showed us how the system works and explained a central challenge: The plant can remove much of what enters with the river, but its performance and costs are tied to what communities upstream send downstream.
[Part 2 of a multi-part series]
“I live within the city limits. I drink the same water that you drink,” Saulsbury told the group. A Pittsboro native and Northwood High School graduate, he said he began working for the town in 2014, moved to the water plant in 2015 and became its administrator around 2020. “I feel like I’m making a difference,” he said.
The tour offered an unusually close look at the ordinary work behind a public necessity. We followed the route of raw water through mixing, settling and filtration equipment, asked how the plant handles changing river conditions, and returned repeatedly to two contaminants that cannot be understood simply by looking at a clear glass: PFAS and 1,4-dioxane.
A plant connected to a river and a growing town
The intake sits near the Haw River dam, before the water is pumped uphill to the treatment facility. Saulsbury pointed out the raw-water building below the road and described two large pumps that operators alternate weekly. That rotation gives each pump operating time and helps the staff manage maintenance.
The Pittsboro Water Filtration Facility is less than a mile from the river. The facility is certified to treat 2 million gallons a day and the plant and townwide storage can hold nearly 3 million gallons of clean water. Those are rated treatment and storage figures, distinct from the volume produced on a particular day. TriRiver’s process guide provides the plant’s eight-step overview.
Asked how much water the plant sends out, Saulsbury said summer demand can bring withdrawals to about 1.7 million gallons a day, with about 1.4 million gallons reaching tanks; in winter, he said, demand can be as low as about 850,000 gallons a day.
The seasonal swing reflects ordinary household and business habits. Lawns need water in summer, vehicles are washed, and outdoor use rises. Winter demand is lighter. The plant can run for long days during the warmer season, Saulsbury said, but at the time of the tour it still shut down at night. Operators generally began around 4:30 a.m.; summer operation could extend past midnight, while winter runs often ended earlier.
That schedule does not mean the community loses service overnight. Treated water is stored before distribution, giving the system a buffer while pumps and treatment units cycle. It does mean that production, storage and demand have to be managed together. A rated capacity of 2 million gallons a day is only one measure of the system’s room to grow; equipment downtime, source-water conditions, staffing and delivery infrastructure also matter.
Saulsbury said the plant was approaching the point where the Sanford connection would become valuable and estimated that the connection could eventually supply roughly 3 million gallons a day. TriRiver’s current project page says the $390 million Sanford filtration expansion would raise that plant’s capacity from 12 million to 30 million gallons a day, with construction and infrastructure connections to Moncure and Pittsboro expected to continue into early 2029. The regional project is intended to serve multiple communities, including Sanford, Pittsboro, Holly Springs and Fuquay-Varina.
For Pittsboro residents, the significance is practical: Another water source and a larger regional system could improve capacity and options during an emergency. The connection does not erase the need to maintain the Haw River plant or protect the river that supplies it today.
The first steps: chemistry makes particles visible
At the intake, Saulsbury said, operators add sodium permanganate to oxidize iron and manganese in the raw water. The river water is then pumped uphill into a flash-mix area where other chemicals are introduced. One adjusts pH. A carbon slurry helps with taste, odor and total organic carbon, a broad measure of carbon-containing material in the water.
The next chemical addition is a coagulant. Instead of trying to capture every tiny suspended particle separately, the plant encourages them to bind together. Rapid mixing spreads the chemicals through the flowing water, and slower mixers in a series of chambers allow the resulting clumps, called floc, to form and grow.
Cory invited us to look down at the water. Near the beginning, the particles were becoming visible; farther along, they had clustered into a form that could settle. One visitor joked about whether the group was already looking at drinking water. Saulsbury answered, “No, this is really the beginning of the process.”
This stage is easy to underestimate because it precedes the filters that many people picture when they think of water treatment. Coagulation and settling remove material that would otherwise burden those filters. The process also affects how effectively later treatment can work: Organic matter left in the water can react with disinfectants and form disinfection byproducts.
The chemistry is sensitive to what arrives from the river. Saulsbury surprised us by saying he welcomes some muddy, high-flow conditions. When rain sends suspended material downstream, the coagulant has particles to attach to and can form heavier floc. During long dry periods, he said, clearer-looking river water can be more difficult to treat at this stage because there is less material to help the clumps form.
That observation does not mean stormwater is inherently cleaner or safer. It is a description of how this particular settling process responds to suspended particles. Changes in runoff may introduce other substances, and the treatment plant still has to meet drinking-water requirements regardless of the weather.
Saulsbury described the plant as pumping approximately 1,200 gallons a minute during the operation he was showing.
Four and a half hours for the water to settle
After the mixing chambers, the water moves through settling basins. Saulsbury pointed to valves set at different openings to spread the flow. Opening them all fully, he said, would let water take a shorter path and carry floc toward the far end before enough of it could settle.
He estimated that a drop of water takes about four and a half hours to travel from one end of the settling process to the other. As the clumps grow heavy, they sink to the bottom; clearer water continues toward the filters. That detention time is not idle time. It is part of the treatment, giving gravity a chance to do work that the downstream filters otherwise would have to shoulder.
Operators also have to remove what collects below. Saulsbury described mechanical equipment that traverses the basin floor each night, sweeping accumulated sludge toward a lagoon. He compared it to a vacuum cleaner moving out and back. The collected material is periodically pumped out for disposal or land application, he said, generally every three or four months.
Water separated from the sludge can be returned through the plant’s handling system before discharge to the river. Saulsbury said staff sample that discharge about every two weeks for such measures as turbidity and total suspended solids under a permit.
The basins also illustrate why treatment is an ongoing operation rather than a single machine. Pumps, valves, mixers, sludge removal, monitoring and operator judgment have to work together. If one stage performs poorly, the next has a harder job. Even when the river looks calm, the staff is managing a moving process rather than simply waiting for water to pass through.
Filters, backwashing and the cost of a cold day
From the basins, our tour reached four conventional filters. Saulsbury said two were inside a building and two outside, but all worked on the same principle. He described layers of sand, anthracite and gravel that trap remaining suspended material as water moves through them.
The filters need periodic cleaning, called backwashing. Operators watch turbidity, the cloudiness of water; head loss, a measure of how much resistance builds as material accumulates; and hours in service. Saulsbury said a filter might run roughly 100 to 115 hours between washes under favorable warm-weather conditions. During winter, when settling and filtration behave differently, he said the interval could fall to about 30 or 40 hours.
Every wash has an operational cost. It takes water and time, produces a waste stream requiring handling, and temporarily removes a filter from service. The material washed out is directed toward the plant’s waste-handling equipment rather than sent straight to a customer. Such work is part of the reason capacity cannot be understood only as the number printed on a design document.
A question from a visitor turned to whether the plant uses finished drinking water to backwash. Saulsbury said the backwash supply was treated but not yet finished water and promised to explain the pumps downstairs.
TriRiver’s sequence continues beyond the conventional filters: disinfectants are added to control microorganisms; additional chemicals protect distribution pipes; water spends time in a clearwell; and granular activated carbon, or GAC, provides an additional treatment step before water is stored and pumped to customers. The utility has two large GAC vessels and normally operates one at a time so the other can be available while carbon media is replaced.
Those steps serve different purposes. Settling and multimedia filtration remove many particles. Disinfection addresses microbial risks. Granular activated carbon captures certain dissolved chemicals by adsorption, in which molecules attach to the carbon’s extensive internal surface. No single step should be assumed to remove every kind of contaminant.
PFAS: What the public test results show
The GAC equipment is central to Pittsboro’s response to PFAS, a group of persistent chemicals that has drawn growing attention in drinking water. TriRiver says Pittsboro invested nearly $3.5 million to install the carbon filters. As carbon gradually accumulates substances from the water, operators test for “breakthrough” and switch vessels when replacement or regeneration is needed.
Saulsbury said PFAS testing was expensive, estimating about $2,500 for each test used in deciding when to change the GAC media. He said the utility had settled on monthly PFAS testing for the carbon system while also paying for other sampling, including testing for 1,4-dioxane and conventional treatment indicators.
TriRiver posts paired raw-water and finished-water PFAS results. They show why it matters to distinguish water entering the plant from water leaving it. On July 27, 2026, for example, the utility reported PFOA at 14 parts per trillion in raw water and 2.6 parts per trillion in finished water; PFOS was 31 parts per trillion in raw water and was not detected in the finished sample. In a June 19 sample, raw-water PFOA and PFOS were each 38 parts per trillion, while the finished values were 5.4 and 1.4, respectively. “Not detected” is a laboratory result below the relevant reporting threshold, rather than proof that no molecule is present.
The June finished-water PFOA reading is above 4 parts per trillion, the federal maximum contaminant level set for that compound. An individual monthly sample is not, by itself, a determination that the utility violated the rule. Compliance calculations, monitoring schedules and effective dates are governed by the regulation. The important public point is that treatment can sharply reduce a compound while leaving a measurable remainder on some dates.
The U.S. Environmental Protection Agency finalized drinking-water limits for several PFAS in 2024. The agency’s current materials say the 4-part-per-trillion levels for PFOA and PFOS remain in place. In May 2026, it proposed a mechanism for eligible systems to seek two additional years, until 2031, to meet those limits; it also proposed rescinding some other PFAS provisions. Those proposals should not be described as final rules. The underlying compliance deadline in the 2024 rule is 2029 unless changed or an exemption is granted.
The different problem posed by 1,4-dioxane
The tour’s most pointed discussion concerned 1,4-dioxane. Saulsbury said GAC, useful for many PFAS, captures only a small fraction of this compound. When a concentrated pulse moves downriver, the plant’s main defense may be to identify its arrival and temporarily stop drawing water until it passes.
He described the uncertainty of tracking such a “slug.” A sample may need to travel to one of a limited number of laboratories, and the results may arrive after the contaminated water has moved. The river itself does not flow at one constant speed: Rainfall and drought change the time between an upstream discharge and the intake. Saulsbury said operators can shut down and restart intermittently when they have enough warning; he recalled a previous event in which they managed to avoid much of the pulse.
Treatment that performs well against one family of chemicals may be ineffective against another. An activated-carbon installation is a significant investment, but it does not eliminate the need for source control, upstream reporting, rapid sampling and emergency operating choices.
The North Carolina Department of Environmental Quality says 1,4-dioxane has been found downstream of wastewater plants in the Cape Fear River basin and describes efforts to identify and reduce discharges. Its published in-stream target value for water-supply waters is 0.35 micrograms per liter. That target for a river is a different measure from a federal finished drinking-water maximum contaminant level. It should not be casually compared with a single plant sample as if the two represented the same legal test.
During our tour, Pittsboro town commissioner John Bonitz said Pittsboro had sued Apollo Chemical over upstream pollution. The town’s dispute is part of the wider argument about who pays when industrial releases impose monitoring and treatment costs on a downstream community.
Saulsbury also described ultraviolet advanced oxidation as a potential technology for destroying 1,4-dioxane and recalled an approximately $189 million figure for installing such a system at the Pittsboro plant.
The responsibilities upstream and at home
One visitor observed that water treatment is a cycle extending well beyond the plant fence. Pollution prevention, industrial pretreatment, wastewater permits, river monitoring, drinking-water treatment and public disclosure all affect what ultimately comes out of a tap. If an upstream source reduces a contaminant before it reaches the river, the downstream plant has less to contend with. If the substance arrives in a form the plant cannot readily remove, operators may have to use storage and timing instead.
Pittsboro also is part of a regional response. TriRiver says GAC operates at the Pittsboro facility, is being added as part of the Sanford expansion and is planned for Siler City. The Siler City project was estimated at about $20 million in an August 2026 announcement, with the design and construction schedule still preliminary. That comparison does not establish that each community faces the same source water or the same PFAS levels; it shows how treatment investments are spreading across the utility’s service area.
There is a workforce story beneath the equipment. Saulsbury introduced another member of the team, Brian Johnson, who was learning the system. The explanations moved easily between chemical reactions, valve settings, sample turnaround, filter cleaning and river conditions. The visible plant is concrete, pipes and tanks, but the process depends on people who know what the readings mean and when a change upstream calls for a change in operations.
TriRiver publishes its treatment-process guide and monthly PFAS data, with links to the underlying laboratory reports. Residents can read the utility’s annual drinking-water report, check alerts about service conditions and ask how sampling and treatment decisions are made.
Our Aug. 18 tour began with Cory Saulsbury saying that he drinks the same water he produces for his neighbors. It ended with our group about to enter the filter building. Between those points, we saw how a muddy river is made clearer and heard why clear water is only part of the story. Pittsboro’s daily task is to run every stage well, test for substances the eye cannot see, and keep watch far beyond the intake.