No health-based violations on EPA record since 2016.
Serves about 56,538 people (16,163 connections) with surface water bought from Walnut Valley Water District, Three Valleys MWD and Covina Valley Water Company.
From EPA's record for CA1910142. PurityMap is independent of GSWC-San Dimas.
Are you this utility? Correct this listing →
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 November 2024 to February 2025.
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Lithium | 57 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 | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorooctanesulfonic acid (PFOS) | 4.5 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| 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 | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| 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 | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| 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 | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| 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 | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| 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 | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| 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 | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-11-18 to 2025-02-26 | UCMR5 Analytical Results: GSWC-SAN DIMAS (CA1910142) |
Screening tells you if something is worth a closer look; a lab result is the number you can act on.
As an Amazon Associate, PurityMap earns from qualifying purchases. Affiliate disclosure
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 →GSWC-San Dimas's phone number on EPA record is 760-515-8322. Its mailing address is 401 S. San Dimas Canyon Road, SAN DIMAS, CA 91773.
According to EPA's record, GSWC-San Dimas uses surface water bought from Walnut Valley Water District, Three Valleys MWD and Covina Valley Water Company.
No health-based violations on EPA record since 2016. The record comes from EPA's SDWIS compliance database.
The 90th-percentile lead result in GSWC-San Dimas's latest lead and copper round, which ended in December 2026, was 2.1 µg/L, below the federal action level of 15 µg/L.
PurityMap has no verified website for GSWC-San Dimas. Its phone number on EPA record is 760-515-8322. Its mailing address on EPA record is 401 S. San Dimas Canyon Road, SAN DIMAS, CA 91773. Your water bill lists the ways to contact your supplier and pay. PurityMap does not take payments.