Perfluorooctanesulfonic acid
5.1ng/L
Each block = 4.0 ng/L federal MCL (2024)
Short answer: PFOS is above its federal limit (a 2024 limit that water systems have until at least 2029 to meet); 1 more is detected with no federal limit, and everything else measured is within its reference or not detected. Williamsport Mun Water Auth serves 51,000 residents.
Your water bill or annual water quality report names your actual supplier.
Also supplies: South Williamsport, Duboistown
The bar is drawn in blocks of the 4.0 ng/L federal MCL (2024), so the length shows how far above it the result sits.
5.1ng/L
Each block = 4.0 ng/L federal MCL (2024)
WILLIAMSPORT MUN WATER AUTH (EPA PWSID PA4410173) delivers surface water to 51,000 residents. This report reflects 29 individual PFAS result(s) from the source UCMR5 observations and the latest Lead & Copper Rule 90th-percentile result. Water hardness and disinfectant type are pending the utility's own annual report.
0health-based violations in the last 10 years
From EPA SDWIS. A clean violation history means no enforcement action was recorded; it does not cover contaminants without a limit.
No result is not a pass. Your utility's annual water quality report may list them, and a certified lab test covers your own tap.
Plumbing inside a home can add lead that the system record can't show. A tap test tells you what reaches your glass.
PFOS 5.1 ng/L, above the 4 ng/L limit (+4 more PFAS detected)
lead 2 µg/L, below the 15 µg/L action level (detected below the limit); 1,690 lead service lines; 5 galvanized lines to replace (context, not a tap measurement)
Screening tells you if something is worth a closer look; a lab result is the number you can act on.
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Screening: quick check, not lab-grade
Safe Home (EnviroTestKits)
Lead, read as one of three ranges: 0–4, 5–15 or 15+ ppb
What it can't tell you: It shows a lead range, not an exact level, and tests nothing else unless you pay extra for the optional lab test.
Lab-certified results
ETR Laboratories
50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria
What it can't tell you: It does not test PFAS, and not every result on the panel falls under the lab's accredited scope.
When your results arrive, read them here →
Each card names which Williamsport findings its current certification covers, and which it doesn't.
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PurityMap does not give a safe/unsafe verdict; it shows what the public records measured. For Williamsport, PFOS 5.1 ng/L was measured above the 4 ng/L federal limit in EPA's 2024 testing; the lead 90th-percentile result was 2 µg/L against the 15 µg/L action level. WILLIAMSPORT MUN WATER AUTH (PWSID PA4410173) has a Purity Score of 70/100 (confidence: moderate), assessed at the water-system level and computed only from contaminants that were measured. Water can change in your own pipes, so a certified test is the only way to know what comes out of your tap.
WILLIAMSPORT MUN WATER AUTH (PWS ID PA4410173) is the public water system on record for Williamsport, Pennsylvania, serving about 51,000 people. Confirm the utility on your water bill before acting on a specific finding.
Surface water (primary source of record in EPA SDWIS).
Yes. In EPA's UCMR 5 testing (2024-03-05 to 2024-12-10), PFOS was measured at 5.1 ng/L against a 4 ng/L federal limit. PFHxA (3.5 ng/L, below the 400,000 ng/L state limit), PFHxS (3.6 ng/L, below the 10 ng/L federal limit) and PFNA (9.7 ng/L, below the 10 ng/L federal limit) were also detected. PFPeA (4.1 ng/L) was also detected; it has no federal or state limit. Reverse osmosis and filters certified to NSF/ANSI 53 for PFOA/PFOS reduce them at the tap.
WILLIAMSPORT MUN WATER AUTH's most recent lead 90th-percentile result (2025) was 2 µg/L, below the 15 µg/L action level. That figure comes from sampled homes; lead usually enters from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
PurityMap's current record for Williamsport holds 31 findings: 1 above a reference, 4 detected within the reference, 1 detected with no limit and 25 not detected. Each finding links to its dated public record; a parameter that was never monitored is shown as pending, not as a pass.
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| Contaminant | Result | Benchmark | Status | Sampled | Source |
|---|---|---|---|---|---|
| Perfluorooctanesulfonic acid (PFOS) | 5.1 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorononanoic acid (PFNA) | 9.7 ng/L | 10 ng/L federal MCL (2024) | Within a historical reference; current applicability unverified | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorohexanesulfonic acid (PFHxS) | 3.6 ng/L | 10 ng/L federal MCL (2024) | Within a historical reference; current applicability unverified | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Lead (90th percentile) | 2 µg/L | 15 µg/L federal action level | Below the listed reference | 2025–2025 monitoring period | Lead & Copper Rule 90th-percentile: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorohexanoic acid (PFHxA) | 3.5 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Within a historical reference; current applicability unverified | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoropentanoic acid (PFPeA) | 4.1 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Contaminant | Result | Benchmark | Status | Sampled | Source |
|---|---|---|---|---|---|
| 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Lithium | < 9 µg/L | 10 µg/L EPA health reference level (screening, not a legal limit)Screening level, not a legal limit | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorobutanesulfonic acid (PFBS) | < 3 ng/L | 2,000 ng/L EPA health advisory (screening, not a legal limit)Screening level, not a legal limit | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-05 to 2024-12-10 | UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173) |
Perfluorooctanesulfonic acid (PFOS)
Perfluorohexanesulfonic acid (PFHxS)
Perfluorohexanoic acid (PFHxA)
Perfluoropentanoic acid (PFPeA)
11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
Perfluoro-3-methoxypropanoic acid (PFMPA)
Perfluoro-4-methoxybutanoic acid (PFMBA)
Perfluorobutanesulfonic acid (PFBS)
Perfluorododecanoic acid (PFDoA)
Perfluoroheptanesulfonic acid (PFHpS)
Perfluoroheptanoic acid (PFHpA)
Perfluoropentanesulfonic acid (PFPeS)
Perfluorotetradecanoic acid (PFTA)
Perfluorotridecanoic acid (PFTrDA)
Perfluoroundecanoic acid (PFUnA)
Every value is the published result from the cited public record. A reporting limit is the lowest level the method could reliably quantify; a non-detect is not a guarantee of zero.
UCMR5 Analytical Results
UCMR5 Analytical Results: WILLIAMSPORT MUN WATER AUTH (PA4410173)
US EPA
State SDWIS Compliance Record
Lead & Copper Rule 90th-percentile: WILLIAMSPORT MUN WATER AUTH (PA4410173)
US EPA SDWIS
Methodology: how we analyze water. Prepared with AI assistance and reviewed by the PurityMap Editorial Team before publication.
Start with the hot-or-cold tap check. Where Williamsport Mun Water Auth reported something related, it's shown below.
Lead at Williamsport Mun Water Auth: 2 µg/L (90th percentile, 2025 monitoring period). Lead has no taste, so a taste neither shows nor rules it out.
A ZIP code is a postal area, not a water service area. Your water bill names your supplier.