Los Osos, CA · PFAS · forever chemicals
Is There PFAS in Los Osos Tap Water?
Los Osos, CA: PFOA 14.7 ng/L, 4× EPA's 4 ng/L limit; PFOS also above. Every PFAS result and filter certifications per compound.
The measurements · EPA UCMR 5
8 of 29 PFAS detected
Each result is read against its own reference. Only PFOA, PFOS and PFHxS have federal limits. PFBA, PFHpA and PFPeA have no federal or state limit and are shown for transparency, not graded.
- PFOAFederal MCLPerfluorooctanoic acid14.7ng/LAbove its limit · sampled 2024-01-08 to 2024-07-08Evidence
- PFOSFederal MCLPerfluorooctanesulfonic acid11.7ng/LAbove its limit · sampled 2024-01-08 to 2024-07-08Evidence
- PFHxSFederal MCLPerfluorohexanesulfonic acid8.4ng/LDetected, below its limit · limit under EPA review · sampled 2024-01-08 to 2024-07-08Evidence
- PFBSEPA health advisoryPerfluorobutanesulfonic acid18ng/LDetected, below its EPA health advisory · sampled 2024-01-08 to 2024-07-08Evidence
- PFHxAState MCL · MichiganPerfluorohexanoic acid16.6ng/LDetected, below its state limit · sampled 2024-01-08 to 2024-07-08Evidence
- PFPeANo limitPerfluoropentanoic acid16.8ng/L
No federal or state limit: shown for transparency, not graded.
Detected, no limit · sampled 2024-01-08 to 2024-07-08Evidence - PFBANo limitPerfluorobutanoic acid6ng/L
No federal or state limit: shown for transparency, not graded.
Detected, no limit · sampled 2024-01-08 to 2024-07-08Evidence - PFHpANo limitPerfluoroheptanoic acid5.4ng/L
No federal or state limit: shown for transparency, not graded.
Detected, no limit · sampled 2024-01-08 to 2024-07-08Evidence
All 29 compounds in this record
- PFOAMCL14.7 ng/L
- PFOSMCL11.7 ng/L
- PFHxSMCL8.4 ng/L
- PFNAMCLNot detected
- HFPO-DA (GenX)MCLNot detected
- PFBS18 ng/L
- PFHxA16.6 ng/L
- PFBA6 ng/L
- PFHpA5.4 ng/L
- PFPeA16.8 ng/L
- 11Cl-PF3OUdSNot detected
- 4:2 FTSNot detected
- 6:2 FTSNot detected
- 8:2 FTSNot detected
- 9Cl-PF3ONSNot detected
- ADONANot detected
- NEtFOSAANot detected
- NFDHANot detected
- NMeFOSAANot detected
- PFDANot detected
- PFDoANot detected
- PFEESANot detected
- PFHpSNot detected
- PFMBANot detected
- PFMPANot detected
- PFPeSNot detected
- PFTANot detected
- PFTrDANot detected
- PFUnANot detected
MCL marks the 5 PFAS given a federal limit in EPA's 2024 rule. EPA has proposed rescinding three of those limits; they apply until a final rule.
Results as a table29 results with limit, status, sample date and source
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Perfluorooctanoic acid (PFOA) | 14.7 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorooctanesulfonic acid (PFOS) | 11.7 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorohexanesulfonic acid (PFHxS) | 8.4 ng/L | 10 ng/L federal MCL (2024) | Within a historical reference; current applicability unverified | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorobutanesulfonic acid (PFBS) | 18 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 | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorohexanoic acid (PFHxA) | 16.6 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Within a historical reference; current applicability unverified | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorobutanoic acid (PFBA) | 6 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoroheptanoic acid (PFHpA) | 5.4 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoropentanoic acid (PFPeA) | 16.8 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| 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 | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| 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 | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| 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 | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| 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 | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| 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 | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-08 to 2024-07-08 | UCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016) |
How this compares
PFOS across 764 cities with a detected value
Los Osos 11.74 ng/L federal MCL (2024)
3,396 more were below the lab's 4 ng/L reporting limit and aren't plotted, and 34 have no result on record. 66 cities above 25 ng/L are grouped in the last bar. A position here is not a verdict on the water.
Where Los Osos sits11.7 ng/L PFOSHigher than 72% of 764 cities with a detected value.
In California
112of 400 city reports
have a regulated PFAS above the federal limit.
PFAS across California →What this record covers
- LOS OSOS COMMUNITY SERVICES DISTRICT's water system as a whole, as reported to EPA UCMR 5.
- 29 PFAS compounds, each with its own result.
- Samples taken 2024-01-08 to 2024-07-08.
What is unknown
- The water at your tap. Building plumbing isn't in this record.
- PFAS not listed in the 29 above were not reported in these records.
- Levels since the last sample have not been published.
Treatment capabilities that apply
Test first, then match a certified method.
A tap test can confirm levels at your home before you choose treatment.
Identified concerns
- PFOA · exceeds the limit
- PFOS · exceeds the limit
- PFBS · detected below the limit
- PFHxA · detected below the limit
- PFHxS · detected below the limit
- PFBA · detected, no federal or state limit
- PFHpA · detected, no federal or state limit
- PFPeA · detected, no federal or state limit
- Reverse osmosisOpen the method →
- Activated carbon (GAC)Open the method →
- Anion exchangeOpen the method →
9 products have a current certification naming a PFAS detected here.See PFAS filters, checked compound by compound ↓
Commercial · PFAS filters
Fit for Los Osos’s PFAS, compound by compound
Each filter is checked against the 8 PFAS detected here. A ✓ needs a current certification record that names the compound. A PFAS claim on the box is not enough.
As an Amazon Associate, PurityMap earns from qualifying purchases. A product appears here only when a current certification record covers at least one identified concern; every concern stays listed. The retail offer is looked up afterwards and never changes which products appear or their order. Affiliate disclosure.
- ✓Certified for this compound
- ?Claimed or likely, not established
- –No claim on record
Under-Sink Filter
Aquasana Claryum 2-Stage Under-Sink Filter (AQ-5200)
Activated Carbon (Claryum)Detected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 53 · PFOA, PFOS
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Under-Sink Filter
Aquasana Claryum 3-Stage Max Flow Under-Sink Filter (AQ-6300M)
Activated Carbon (Claryum)Detected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 53 · PFOA, PFOSNSF/ANSI 42
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Countertop System
Aquasana Clean Water Machine Countertop Filter (AQ-CWM2)
Activated Carbon (Claryum)Detected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 53 · PFOA, PFOSNSF/ANSI 42
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Countertop System
Patriot Pure Ultimate Water Filtration System
Gravity pour-through (Nanomesh filter)Detected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 53 · PFOA, PFOS
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Countertop System
AquaTru Carafe Countertop Reverse-Osmosis Purifier (AT100)
Reverse OsmosisDetected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 58NSF/ANSI 53 · PFOA, PFOSNSF/ANSI 42
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Countertop System
AquaTru Classic Countertop Reverse-Osmosis Purifier (AT2000)
Reverse OsmosisDetected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 58NSF/ANSI 53 · PFOA, PFOSNSF/ANSI 42
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Under-Sink Filter
Waterdrop G3P600 Tankless Reverse-Osmosis System
Reverse OsmosisDetected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 58NSF/ANSI 53 · PFOA, PFOSNSF/ANSI 42
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Under-Sink Filter
Waterdrop G3P800 Tankless Reverse-Osmosis System
Reverse OsmosisDetected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 53 · PFOA, PFOSNSF/ANSI 58NSF/ANSI 42
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
Refrigerator Filter
Whirlpool Filter 3 Refrigerator Water Filter (WHR3RXD1)
Activated CarbonDetected in Los Osos2 of 8 certified
- PFOA14.7 ng/L✓Certified for this compound
- PFOS11.7 ng/L✓Certified for this compound
- PFBS18 ng/L–No claim on record
- PFHxA16.6 ng/L–No claim on record
- PFHxS8.4 ng/L–No claim on record
- PFBA6 ng/L–No claim on record
- PFHpA5.4 ng/L–No claim on record
- PFPeA16.8 ng/L–No claim on record
CertifiedNSF/ANSI 53 · PFOA, PFOSNSF/ANSI 42NSF/ANSI 401
Certified for PFOA, PFOS; not established for PFBS, PFHxA, PFHxS, PFBA, PFHpA, PFPeA.
- Browse, not a match:
- Brita Elite Water Filter Pitcher
- Clearly Filtered Pitcher (lab-tested, not NSF 53 certified)
- Culligan ZeroWater 10-Cup Pitcher (ZEROP10)
- Frizzlife SP99 Under-Sink Filter
None of these is certified for all 8 compounds detected here. A tap test first tells you which ones reach your glass.
Questions
Frequently asked
Follow this water
Get Los Osos updates
We'll email you when new PFAS results are published for Los Osos.
Double opt-in: we email a confirmation link. Unsubscribe anytime. No spam.
Is there PFAS in Los Osos tap water?
In EPA's UCMR 5 testing of LOS OSOS COMMUNITY SERVICES DISTRICT (2024-01-08 to 2024-07-08): PFBA 6 ng/L (no federal or state limit), PFBS 18 ng/L (EPA health advisory 2,000), PFHpA 5.4 ng/L (no federal or state limit), PFHxA 16.6 ng/L (state limit 400,000), PFHxS 8.4 ng/L (limit 10), PFOA 14.7 ng/L (limit 4), PFOS 11.7 ng/L (limit 4), PFPeA 16.8 ng/L (no federal or state limit) and the other 21 PFAS tested not detected. "Not detected" means below the lab's reporting limit, not proven zero.
What are the federal PFAS limits?
EPA's 2024 drinking-water rule set maximum contaminant levels of 4.0 ng/L for PFOA and for PFOS, and 10 ng/L for PFHxS, PFNA and HFPO-DA (GenX). In May 2026 EPA proposed keeping the PFOA and PFOS limits, with the option of until 2031 to comply, and rescinding the other three. Until a final rule, all five limits apply. Results above them today are above the limits in force.
How do I remove PFAS from my tap water?
Reverse-osmosis systems and filters certified to NSF/ANSI 53 or 58 for PFOA/PFOS reduction are the proven options at the tap. Check the certifier's listing (NSF, WQA or IAPMO) for the exact model, and replace cartridges on schedule.
- UCMR5 Analytical ResultsUCMR5 Analytical Results: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016)US EPA · 2026-01-15View source ↗
- State SDWIS Compliance RecordLead & Copper Rule 90th-percentile: LOS OSOS COMMUNITY SERVICES DISTRICT (CA4010016)US EPA SDWIS · 2026-07-09View source ↗