Does Knightdale, NC Water Have PFAS? What Raleigh Water's Testing Shows

Triangle Waterworks · informational guide

Direct answer: Yes, in trace amounts. Raleigh Water — Knightdale's supplier — found PFOS between 1.15 and 2.98 ppt and PFOA between 2.21 and 2.94 ppt in 2025 testing, every quarter under the EPA's 4.0 ppt limit. That's a legal ceiling, not zero risk. New-construction plumbing doesn't filter PFAS out — a carbon stage in the all-in-one system does, alongside softening for your new water heater.

Does Knightdale, NC water have PFAS?

Yes. Knightdale is one of seven towns Raleigh Water supplies, and the utility's own 2025 Perfluorinated Compounds Data Results show PFOS at 1.15–2.98 parts per trillion and PFOA at 2.21–2.94 ppt in finished water across all four quarters — every single reading under the EPA's 4.0 ppt Maximum Contaminant Level. PFBS came in at 2.58–3.14 ppt and PFHxS ranged non-detect to 0.996 ppt. PFNA and GenX were non-detect.

Raleigh Water's data also states that the Hazard Index running annual average — a combined measure across several PFAS compounds — did not exceed 1, and no violation occurred. That's a genuinely clean compliance record. It is not the same as a zero reading.

What did Raleigh Water's 2025 testing find in Knightdale's water?

A broader snapshot than PFAS alone, since a new Knightdale household is buying a house, not a single contaminant fix. Raleigh Water's 2025 Consumer Confidence Report and PFAS data cover disinfection byproducts and hardness too — all reported below their limits.

Does a brand-new house in Knightdale still need water treatment?

Yes. New construction solves for structure, not water chemistry. A brand-new PEX or copper supply line carries whatever Raleigh Water delivers to the meter — including the PFAS, chloramine, and disinfection byproducts in the table above — straight to your fixtures untouched.

The upside of building new is timing. Installing an all-in-one system before you've furnished the house means no retrofit around finished walls, and a fresh water heater starts its life protected from mineral buildup instead of scaling for a few years first. For the mechanics of fitting treatment into a new Knightdale build, see new construction water treatment in Knightdale, NC.

Why is "under the EPA limit" a ceiling, not a guarantee of zero risk?

Because the 4.0 ppt MCL reflects EPA's own risk tolerance for the whole country, not a statement that any detectable level is harmless. PFOS and PFOA showed up in every one of Raleigh Water's four 2025 quarters, just below that ceiling each time. Detectable is not the same as absent.

That distinction matters for how you treat it. A system that relies on staying under a legal number is still leaving PFAS in the water you drink. A system that removes it — carbon certified to NSF/ANSI 53 or P473, or reverse osmosis certified to NSF/ANSI 58 — doesn't depend on where the ceiling sits.

Does boiling water remove PFAS from Knightdale tap water?

No. Boiling only evaporates water, not the PFAS dissolved in it. The compound stays behind, so a smaller volume of water ends up carrying the same total amount — boiling can concentrate PFAS rather than reduce it. It's an effective fix for bacteria, not for a fluorinated compound like this one.

What about the annual chlorine switch and disinfection byproducts in Knightdale's water?

Raleigh Water normally disinfects with chloramine, which the City describes as carrying little taste or odor. Once a year, on the recommendation of the N.C. Department of Environmental Quality, the system switches to free chlorine only and flushes the distribution network — the 2026 period ran February 26 through April 2. Chlorine residual runs higher system-wide during that window, and some temporary discoloration can occur while lines flush.

That process also produces trihalomethanes (TTHM) and haloacetic acids (HAA5), byproducts of disinfecting the water in the first place. Raleigh's 2025 CCR reports TTHM averaging 34.2 ppb (up to 42.8) against an 80 ppb limit, and HAA5 averaging 22.0 ppb (up to 33.6) against a 60 ppb limit — both compliant.

EPA's own National Primary Drinking Water Regulations table states the potential health effects from long-term exposure to TTHMs above the MCL as "Liver, kidney or central nervous system problems; increased risk of cancer." For HAA5, the listed effect is "Increased risk of cancer." Those are EPA's own words for exposure above the legal limit over the long term — not a claim about Knightdale's current, compliant water, which is the exact reason the standard exists at that level in the first place.

What actually removes PFAS and disinfection byproducts from Knightdale water?

Activated carbon, certified for the job. Carbon rated to NSF/ANSI 53 or P473 handles PFAS; the same carbon media is also what removes chlorine, chloramine taste, and TTHM/HAA5. A water softener alone does none of this — it's ion exchange built for calcium and magnesium, with no mechanism for a fluorinated compound or a disinfection byproduct.

That's why the all-in-one system pairs both halves: softening resin protects a new water heater, dishwasher, and plumbing from the hardness in the table above, while a PFAS-rated carbon stage handles what softening never touches. One install at move-in covers both. See who installs water softeners in Knightdale, NC and water softener cost in Knightdale, NC for what that install looks like locally.

Get your new Knightdale home tested at your own address

Raleigh Water's system-wide numbers are a starting point, not your specific tap. Take the 60-second water quiz to see which all-in-one system fits a new Knightdale build, or book a free water analysis to get a number tied to your actual address. For the full local picture, start at water treatment in Knightdale, NC.

FAQ

Does Knightdale, NC tap water contain PFAS? Yes. Raleigh Water's 2025 testing found PFOS at 1.15–2.98 ppt and PFOA at 2.21–2.94 ppt across all four quarters, both under the EPA's 4.0 ppt limit. PFBS and PFHxS were also detected; PFNA and GenX were not.

I just closed on a new-construction home in Knightdale — do I still need to worry about water quality? Yes. New plumbing carries the same Raleigh Water supply as an older home; PVC, PEX, or copper pipe doesn't filter anything out. Installing an all-in-one system before you move furniture in is the easiest time to add it, and it protects a brand-new water heater from day one.

Is Knightdale's water considered hard? Raleigh Water's 2025 CCR shows hardness averaging 21.9–35.3 ppm, roughly 1.3–2.1 gpg on the WQA/Hach scale — that's slightly hard, not soft and not the harder band that starts at 7 gpg. Our own in-home testing across the area measures 1.6–3.7 gpg depending on ZIP, which is why an address-level test matters more than a system average.

My builder installed a basic water softener — does that cover PFAS too? No. A standard softener is ion exchange for calcium and magnesium only; it has no mechanism for PFAS or disinfection byproducts. Those need carbon certified to NSF/ANSI 53 or P473 (or RO certified to NSF/ANSI 58), which is why the all-in-one system pairs a carbon stage with the softening resin.

Does Raleigh Water's annual chlorine switch affect Knightdale? Yes — Knightdale is on the same Raleigh Water system, so the once-a-year switch from chloramine to free chlorine and the distribution flush applies here too. It typically runs from late February into early April, with the exact dates announced by the City each year.

Is it worth testing my own Knightdale address instead of relying on the system-wide numbers? Yes. Raleigh Water's PFAS and CCR figures are system-wide averages and ranges, not a reading from your specific tap. A free water analysis gives you your address's own numbers and a system sized to match, rather than an assumption based on the town average.

Sources

• Raleigh Water — Perfluorinated Chemicals Data and Information
• City of Raleigh — 2025 Water Consumer Confidence Report
• EPA — National Primary Drinking Water Regulations

Related reading: Triangle NC PFAS & Forever Chemicals Explainer | Water Treatment in Knightdale, NC | New Construction Water Treatment in Knightdale, NC | Water Softener Cost in Knightdale, NC | Pesticides & Herbicides in Knightdale, NC Water