No health-based violations on EPA record since 2016.
Serves about 39,730 people (11,295 connections) with surface water bought from City of Upland and Three Valleys MWD.
From EPA's record for CA1910024. PurityMap is independent of GSWC.
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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 September 2023 to November 2024.
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Perfluorooctanoic acid (PFOA) | 12.9 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorooctanesulfonic acid (PFOS) | 10.4 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorohexanesulfonic acid (PFHxS) | 3.7 ng/L | 10 ng/L federal MCL (2024) | Within a historical reference; current applicability unverified | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorobutanesulfonic acid (PFBS) | 5.1 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 | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorohexanoic acid (PFHxA) | 8.4 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Within a historical reference; current applicability unverified | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoroheptanoic acid (PFHpA) | 4.6 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoropentanoic acid (PFPeA) | 6.4 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| 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 | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| 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 | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| 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 | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| 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 | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| 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 | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| 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 | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-09-18 to 2024-11-25 | UCMR5 Analytical Results: GSWC - CLAREMONT (CA1910024) |
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 →GSWC'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 uses surface water bought from City of Upland and Three Valleys MWD.
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's latest lead and copper round, which ended in December 2026, was 5.6 µg/L, below the federal action level of 15 µg/L.
PurityMap has no verified website for GSWC. 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.