Short answer: No measured result is above a legal limit; the water is moderately hard. Marin Municipal Water District serves 188,116 residents.
Your water bill or annual water quality report names your actual supplier.
Also supplies: Mill Valley, Larkspur, San Anselmo, Tamalpais-Homestead Valley, Corte Madera, Tiburon, Fairfax, Sausalito, Ross, Belvedere
MARIN MUNICIPAL WATER DISTRICT (EPA PWSID CA2110002) delivers surface water to 188,116 residents. This report reflects 29 individual PFAS result(s) from the source UCMR5 observations and the latest Lead & Copper Rule 90th-percentile result. The utility's 2025 CCR reports moderately hard water.
0health-based violations in the last 10 years
From EPA SDWIS. A clean violation history means no enforcement action was recorded; it does not cover contaminants without a limit.
No result is not a pass. Your utility's annual water quality report may list them, and a certified lab test covers your own tap.
The records describe the system. A certified lab test shows what reaches your glass.
For what was detected in San Rafael: Ion-exchange water softener, Salt-free conditioner, Reverse osmosis (point-of-use).
Water treatment technologies →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
Silver Lake Research
Lead, bacteria, nitrate, copper, iron, chlorine, hardness and pH
What it can't tell you: Each test gives a yes/no or a rough range, not a lab number, and it cannot detect PFAS or arsenic.
Lab-certified results
ETR Laboratories
50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria
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.
When your results arrive, read them here →
PurityMap does not give a safe/unsafe verdict; it shows what the public records measured. For San Rafael, no regulated PFAS were detected in EPA's 2024 testing. MARIN MUNICIPAL WATER DISTRICT (PWSID CA2110002) has a Purity Score of 100/100 (confidence: moderate), assessed at the water-system level and computed only from contaminants that were measured. Water can change in your own pipes, so a certified test is the only way to know what comes out of your tap.
MARIN MUNICIPAL WATER DISTRICT (PWS ID CA2110002) is the public water system on record for San Rafael, California, serving about 188,116 people. Confirm the utility on your water bill before acting on a specific finding.
Surface water (primary source of record in EPA SDWIS).
None of the 29 PFAS in EPA's UCMR 5 testing (2023-08-02 to 2024-06-10) was detected. "Not detected" means below the lab's reporting limit, not proven zero.
Lead is not in San Rafael's current published record. Lead usually enters from a building's own pipes and fixtures, so a certified home test is the way to know yours.
PurityMap's current record for San Rafael holds 32 findings: 1 detected within the reference and 31 not detected. Each finding links to its dated public record; a parameter that was never monitored is shown as pending, not as a pass.
San Rafael's water is recorded as 5 gpg, moderately hard. Hardness is an aesthetic and plumbing characteristic, not a health-based limit.
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| Contaminant | Result | Benchmark | Status | Sampled | Source |
|---|---|---|---|---|---|
| Water hardness | 5 gpg | Aesthetic, no federal health limit | Within a secondary/aesthetic reference | 2025 | Marin Water (Marin Municipal Water District) 2025 Consumer Confidence Report (CCR) |
| Contaminant | Result | Benchmark | Status | Sampled | Source |
|---|---|---|---|---|---|
| 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 | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| 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 | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| 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 | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| 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 | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| 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 | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Lead (90th percentile) | Non-Detect (ND) | 15 µg/L federal action level | Not detected above the reporting limit | 2019–2021 monitoring period | Lead & Copper Rule 90th-percentile: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| 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 | 2023-07-10 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-07-10 to 2024-07-08 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-07-10 to 2024-07-08 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| 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 | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorooctanesulfonic acid (PFOS) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-07-10 to 2024-07-08 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-07-10 to 2024-07-08 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-08-02 to 2024-06-10 | UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002) |
11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
Perfluoro-3-methoxypropanoic acid (PFMPA)
Perfluoro-4-methoxybutanoic acid (PFMBA)
Perfluorobutanesulfonic acid (PFBS)
Perfluorododecanoic acid (PFDoA)
Perfluoroheptanesulfonic acid (PFHpS)
Perfluoroheptanoic acid (PFHpA)
Perfluorohexanesulfonic acid (PFHxS)
Perfluorohexanoic acid (PFHxA)
Perfluorooctanesulfonic acid (PFOS)
Perfluoropentanesulfonic acid (PFPeS)
Perfluoropentanoic acid (PFPeA)
Perfluorotetradecanoic acid (PFTA)
Perfluorotridecanoic acid (PFTrDA)
Perfluoroundecanoic acid (PFUnA)
Every value is the published result from the cited public record. A reporting limit is the lowest level the method could reliably quantify; a non-detect is not a guarantee of zero.
UCMR5 Analytical Results
UCMR5 Analytical Results: MARIN MUNICIPAL WATER DISTRICT (CA2110002)
US EPA
State SDWIS Compliance Record
Lead & Copper Rule 90th-percentile: MARIN MUNICIPAL WATER DISTRICT (CA2110002)
US EPA SDWIS
Consumer Confidence Report (CCR)
Marin Water (Marin Municipal Water District) 2025 Consumer Confidence Report (CCR)
Marin Water (Marin Municipal Water District)
Methodology: how we analyze water. Prepared with AI assistance and reviewed by the PurityMap Editorial Team before publication.
Start with the hot-or-cold tap check. Where Marin Municipal Water District reported something related, it's shown below.
Lead at Marin Municipal Water District: not detected (90th percentile, 2019–2021 monitoring period). Lead has no taste, so a taste neither shows nor rules it out.
A ZIP code is a postal area, not a water service area. Your water bill names your supplier.