No open health-based violations on EPA record in the last 10 years; latest legal-limit breach in the period starting April 2021.
Serves about 7,772 people (2,355 connections) with surface water from its own intake, and buys water from Konocti County Water District and Golden State Water Co.-Clearlake System.
From EPA's record for CA1710003. PurityMap is independent of Highlands Mutual Water Company.
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4 health-based violations in the last 10 years, from EPA's SDWIS compliance database.
| Period | Contaminant | Measured | Legal limit | EPA status |
|---|---|---|---|---|
| Apr–Jun 2021 | Haloacetic acids (HAA5) | 61.125 mg/L | 0.060 mg/L | Resolved |
| Jan–Mar 2021 | Haloacetic acids (HAA5) | 0.064 mg/L | 0.060 mg/L | Resolved |
| Apr–Jun 2019 | Haloacetic acids (HAA5) | 61.4 µg/L | 0.060 mg/L | Resolved |
| Jan–Mar 2019 | Haloacetic acids (HAA5) | 61 µg/L | 0.060 mg/L | Resolved |
EPA required this system to test for 30 unregulated and emerging contaminants, from February 2024 to February 2025.
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Lithium | 25 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 | 2024-02-06 to 2024-11-05 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| 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 | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| 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 | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| 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 | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| 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 | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| 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 | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-01-07 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-01-07 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| 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 | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorooctanesulfonic acid (PFOS) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-01-07 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-01-07 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-02-06 to 2025-02-24 | UCMR5 Analytical Results: HIGHLANDS MUTUAL WATER COMPANY (CA1710003) |
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 →Highlands Mutual Water Company's phone number on EPA record is 707-994-8676. Its mailing address is 14774 Hillcrest Avenue, CLEARLAKE, CA 95422.
According to EPA's record, Highlands Mutual Water Company uses surface water from its own intake, and buys water from Konocti County Water District and Golden State Water Co.-Clearlake System.
EPA's record shows 4 health-based violations for Highlands Mutual Water Company 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 April 2021. EPA also lists 1 missed or late test or report in 10 years. The record comes from EPA's SDWIS compliance database.
The 90th-percentile lead result in Highlands Mutual Water Company's latest lead and copper round, which ended in December 2023, was 4.6 µg/L, below the federal action level of 15 µg/L.
PurityMap has no verified website for Highlands Mutual Water Company. Its phone number on EPA record is 707-994-8676. Its mailing address on EPA record is 14774 Hillcrest Avenue, CLEARLAKE, CA 95422. Your water bill lists the ways to contact your supplier and pay. PurityMap does not take payments.