Short answer: No measured result is above a legal limit. Coastside County Water District serves 19,033 residents.
Your water bill or annual water quality report names your actual supplier.
COASTSIDE COUNTY WATER DISTRICT (EPA PWSID CA4110011) delivers surface water to 19,033 residents. This report reflects 29 individual PFAS result(s) from the source UCMR5 observations and the latest Lead & Copper Rule 90th-percentile result. Water hardness and disinfectant type are pending the utility's own annual report.
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.
Plumbing inside a home can add lead that the system record can't show. A tap test tells you what reaches your glass.
lead 1.6 µg/L, below the 15 µg/L action level
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
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
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 →
Each card names which Half Moon Bay findings its current certification covers, and which it doesn't.
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PurityMap does not give a safe/unsafe verdict; it shows what the public records measured. For Half Moon Bay, no regulated PFAS were detected in EPA's 2024 testing; the lead 90th-percentile result was 1.6 µg/L against the 15 µg/L action level. COASTSIDE COUNTY WATER DISTRICT (PWSID CA4110011) has a Purity Score of 98/100 (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.
COASTSIDE COUNTY WATER DISTRICT (PWS ID CA4110011) is the public water system on record for Half Moon Bay, California, serving about 19,033 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 (2024-03-20 to 2025-04-02) was detected. "Not detected" means below the lab's reporting limit, not proven zero.
COASTSIDE COUNTY WATER DISTRICT's most recent lead 90th-percentile result (2022–2024) was 1.6 µg/L, below the 15 µg/L action level. That figure comes from sampled homes; lead usually enters from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
PurityMap's current record for Half Moon Bay holds 31 findings: 1 detected within the reference and 30 not detected. Each finding links to its dated public record; a parameter that was never monitored is shown as pending, not as a pass.
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| Contaminant | Result | Benchmark | Status | Sampled | Source |
|---|---|---|---|---|---|
| Lead (90th percentile) | 1.6 µg/L | 15 µg/L federal action level | Below the listed reference | 2022–2024 monitoring period | Lead & Copper Rule 90th-percentile: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 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 | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 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 | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 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 | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 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 | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 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 | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 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 | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| 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 | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorooctanesulfonic acid (PFOS) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-03-20 to 2025-04-02 | UCMR5 Analytical Results: COASTSIDE COUNTY WATER DISTRICT (CA4110011) |
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: COASTSIDE COUNTY WATER DISTRICT (CA4110011)
US EPA
State SDWIS Compliance Record
Lead & Copper Rule 90th-percentile: COASTSIDE COUNTY WATER DISTRICT (CA4110011)
US EPA SDWIS
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 Coastside County Water District reported something related, it's shown below.
Lead at Coastside County Water District: 1.6 µg/L (90th percentile, 2022–2024 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.