No health-based violations on EPA record since 2016.
Serves about 22,592 people (9,933 connections) with surface water bought from Charleston Water System.
From EPA's record for SC1020002. PurityMap is independent of St John's Water (Sc1020002).
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No health-based violations in the last 10 years, from EPA's SDWIS compliance database.
EPA required this system to test for 30 unregulated and emerging contaminants, from January 2025 to October 2025.
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Perfluorooctanesulfonic acid (PFOS) | 8.5 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorooctanoic acid (PFOA) | 5.4 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorobutanesulfonic acid (PFBS) | 4.5 ng/L | 2,000 ng/L EPA health advisory (screening, not a legal limit)Screening level, not a legal limit | Within the referenced health-based guidance value | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorohexanoic acid (PFHxA) | 4.9 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Within a historical reference; current applicability unverified | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoropentanoic acid (PFPeA) | 5.6 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| 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 | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| 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 | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| 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 | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| 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 | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| 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 | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| 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 | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2025-01-06 to 2025-10-01 | UCMR5 Analytical Results: ST JOHN'S WATER (SC1020002) (SC1020002) |
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 →St John's Water (Sc1020002)'s phone number on EPA record is 843-559-0186. Its mailing address is PO BOX 629, JOHNS ISLAND, SC 29457.
According to EPA's record, St John's Water (Sc1020002) uses surface water bought from Charleston Water System.
No health-based violations on EPA record since 2016. The record comes from EPA's SDWIS compliance database.
The 90th-percentile lead result in St John's Water (Sc1020002)'s latest lead and copper round, which ended in December 2025, was 2 µg/L, below the federal action level of 15 µg/L.
PurityMap has no verified website for St John's Water (Sc1020002). Its phone number on EPA record is 843-559-0186. Its mailing address on EPA record is PO BOX 629, JOHNS ISLAND, SC 29457. Your water bill lists the ways to contact your supplier and pay. PurityMap does not take payments.