No open health-based violations on EPA record in the last 10 years; latest legal-limit breach in the period starting October 2023.
Serves about 7,675 people (153 connections) with surface water from its own intake.
From EPA's record for WY5680085. PurityMap is independent of Ynp-Old Faithful.
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10 health-based violations in the last 10 years, from EPA's SDWIS compliance database.
| Period | Contaminant | Measured | Legal limit | EPA status |
|---|---|---|---|---|
| From July 2024 | Lead and Copper Rule | – | TT | Resolved |
| From June 2024 | Lead and Copper Rule | – | TT | Resolved |
| From March 2024 | Lead and Copper Rule | – | TT | Resolved |
| From November 2023 | Lead and Copper Rule | – | TT | Resolved |
| From October 2023 | Arsenic | 0.012 mg/L | 0.010 mg/L | Resolved |
| Period | Contaminant | Measured | Legal limit | EPA status |
|---|---|---|---|---|
| From July 2023 | Arsenic | 0.012 mg/L | 0.010 mg/L | Resolved |
| From April 2023 | Arsenic | 0.011 mg/L | 0.010 mg/L | Resolved |
| From September 2022 | Long Term 2 Enhanced Surface Water Treatment Rule | – | – | Resolved |
| From June 2022 | Interim Enhanced Surface Water Treatment Rule | – | – | Resolved |
| From January 2020 | Arsenic | 0.011 mg/L | 0.010 mg/L | Resolved |
EPA required this system to test for 30 unregulated and emerging contaminants, from February 2023 to November 2023.
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Lithium | 120 µg/L | 10 µg/L EPA health reference level (screening, not a legal limit)Screening level, not a legal limit | Above the referenced health-based guidance value | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| 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 | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| 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 | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| 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 | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| 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 | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| 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 | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| 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 | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorooctanesulfonic acid (PFOS) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-02-27 to 2023-11-20 | UCMR5 Analytical Results: YNP-OLD FAITHFUL (WY5680085) |
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
Turnaround: 5 minutes
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
Environmental Testing and Research Laboratories (ETR Labs), Leominster, MA · ISO/IEC 17025:2017, ANAB certificate AT-2638 · 2–4 business days after the lab receives it
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.
Get PurityMap updates about this water system.
Follow this water →According to EPA's record, Ynp-Old Faithful uses surface water from its own intake.
EPA's record shows 10 health-based violations for Ynp-Old Faithful in the 10 years to July 9, 2026. No open health-based violations on EPA record in the last 10 years. The latest legal-limit breach on record was in the period starting October 2023. EPA also lists 7 missed or late tests or reports in 10 years. The record comes from EPA's SDWIS compliance database.
The 90th-percentile lead result in Ynp-Old Faithful's latest lead and copper round, which ended in December 2025, was 6 µg/L, below the federal action level of 15 µg/L.
PurityMap has no verified website for Ynp-Old Faithful. Its mailing address on EPA record is P.O. Box 168, YELLOWSTONE, WY 82190. Your water bill lists the ways to contact your supplier and pay. PurityMap does not take payments.