No health-based violations on EPA record since 2016.
Serves about 30,618 people (11,032 connections) with groundwater from its own wells, and buys water from Nacimiento Water Project.
From EPA's record for CA4010002. PurityMap is independent of Atascadero Mutual Water Co.
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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 April 2023 to October 2023.
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Perfluorooctanesulfonic acid (PFOS) | 22.3 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorooctanoic acid (PFOA) | 8.4 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Lithium | 20.7 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 | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorohexanesulfonic acid (PFHxS) | 7.6 ng/L | 10 ng/L federal MCL (2024) | Within a historical reference; current applicability unverified | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorobutanesulfonic acid (PFBS) | 9.4 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 | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorobutanoic acid (PFBA) | 10 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| 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 | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| 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 | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| 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 | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| 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 | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| 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 | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-04-19 to 2023-10-11 | UCMR5 Analytical Results: ATASCADERO MUTUAL WATER CO (CA4010002) |
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 →Atascadero Mutual Water Co's phone number on EPA record is 805-400-5851. Its mailing address is 5005 El Camino Real, ATASCADERO, CA 93422.
According to EPA's record, Atascadero Mutual Water Co uses groundwater from its own wells, and buys water from Nacimiento Water Project.
No health-based violations on EPA record since 2016. The record comes from EPA's SDWIS compliance database.
Lead was not detected at the 90th percentile of tap samples in Atascadero Mutual Water Co's latest lead and copper round, which ended in December 2025. The federal action level is 15 µg/L.
PurityMap has no verified website for Atascadero Mutual Water Co. Its phone number on EPA record is 805-400-5851. Its mailing address on EPA record is 5005 El Camino Real, ATASCADERO, CA 93422. Your water bill lists the ways to contact your supplier and pay. PurityMap does not take payments.