Drinking water quality · 2026
· Verified
What's in City of Cupertino, CA tap water
50 contaminants were measured in the City of Cupertino, CA water system's 2026 annual report. Each is shown below against its federal limit.
- Reporting year
- 2026
- Contaminants measured
- 50
- Over federal limit
- 0
- Approaching the limit
- 0
- Service area
- CA
state-level CCR
Where your water comes from · EPA SDWIS
City of Cupertino, CA's drinking water comes from ground water, drawn from 2 sources.
Source
2ground water
- FLOWERING PEAR COURT
- FRANCO COURT
Treatment
1treatment plant
- MANN STATION CHLORINATION STATION
Distribution
0storage units
Also buys water from SANTA CLARA VALLEY WATER DISTRICT, SAN JOSE WATER, and 1 more.
Source: EPA SDWIS facilities inventory. Methodology.
Historical readings · EPA Six-Year Review (2012–2019)
4 historically-detected contaminants in City of Cupertino, CA
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
NITRATE worst: 2012 | 4.52 mg/L within | 10 mg/L | '12'13'15'16'17'18'19 |
NITRATE NITRITE worst: 2016 | 4.5 mg/L within | 10 mg/L | '16'19 |
BARIUM worst: 2012 | 0.12 mg/L within near national p90 | 2 mg/L | '12'13'16'19 |
FLUORIDE worst: 2013 | 0.21 mg/L within | 4 mg/L | '12'13'16'19 |
PWSID CA4310018 · Source: EPA Six-Year Review 4 (2012–2019). Values are the highest detection in each calendar year; non-detect years are omitted. Year tags above show every year with a detection.
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Combined RadiumCombined radium-226 and radium-228 — naturally occurring radioactive elements. | 0.2886666666666667 PCI/LAverageSource water | 5 PCI/LMCL | Within the limit |
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | Not detected PCI/LHighest single sampleSource water | 15 PCI/LMCL | None detected |
| UraniumA naturally occurring radioactive metal from erosion of natural deposits. | Not detected PCI/LHighest single sampleSource water | 20 PCI/LMCL | None detected |
Other
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Carbofuran | Not detected UG/LHighest single sampleSource water | 18 UG/LMCL | None detected |
| Chlordane | Not detected UG/LHighest single sampleSource water | 0.1 UG/LMCL | None detected |
| Deha | Not detected UG/LHighest single sampleSource water | 400 UG/LMCL | None detected |
| Dehp | Not detected UG/LHighest single sampleSource water | 4 UG/LMCL | None detected |
| Dinoseb | Not detected UG/LHighest single sampleSource water | 7 UG/LMCL | None detected |
| Diquat | Not detected UG/LHighest single sampleSource water | 20 UG/LMCL | None detected |
| Edb | Not detected UG/LHighest single sampleSource water | 0.05 UG/LMCL | None detected |
| Endothall | Not detected UG/LHighest single sampleSource water | 100 UG/LMCL | None detected |
| Endrin | Not detected UG/LHighest single sampleSource water | 2 UG/LMCL | None detected |
| Glyphosate | Not detected UG/LHighest single sampleSource water | 700 UG/LMCL | None detected |
| Heptachlor | Not detected UG/LHighest single sampleSource water | 0.01 UG/LMCL | None detected |
| Heptachlor Epoxide | Not detected UG/LHighest single sampleSource water | 0.01 UG/LMCL | None detected |
| Hexachlorobenzene | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Hexachlorocyclopentadiene | Not detected UG/LHighest single sampleSource water | 50 UG/LMCL | None detected |
| Methoxychlor | Not detected UG/LHighest single sampleSource water | 30 UG/LMCL | None detected |
| Oxamyl | Not detected UG/LHighest single sampleSource water | 50 UG/LMCL | None detected |
| Pcb Total | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Pentachlorophenol | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Picloram | Not detected UG/LHighest single sampleSource water | 500 UG/LMCL | None detected |
| Toxaphene | Not detected UG/LHighest single sampleSource water | 3 UG/LMCL | None detected |
| Twofourd | Not detected UG/LHighest single sampleSource water | 70 UG/LMCL | None detected |
PFAS ("forever chemicals")
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid, a chlorinated PFAS compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)ADONA, a newer-generation PFAS replacement compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| 4:2 Fluorotelomer sulfonic acid (4:2 FTS)4:2 fluorotelomer sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| 6:2 Fluorotelomer sulfonic acid (6:2 FTS)6:2 fluorotelomer sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| 8:2 Fluorotelomer sulfonic acid (8:2 FTS)8:2 fluorotelomer sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (9Cl-PF3ONS)9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid, a chlorinated PFAS compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Hexafluoropropylene oxide dimer acidHFPO-DA ('GenX chemicals'), a newer-generation PFAS replacement compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoro-3-methoxypropanoic acid (PFMPA)Perfluoro-3-methoxypropanoic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoro-4-methoxybutanoic acid (PFMBA)Perfluoro-4-methoxybutanoic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoro(2-ethoxyethane)sulfonic acid (PFEESA)Perfluoro(2-ethoxyethane)sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluorodecanoic acid (PFDA)Perfluorodecanoic acid, a longer-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluorododecanoic acid (PFDoA)Perfluorododecanoic acid, a longer-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoroheptanesulfonic acid (PFHpS)Perfluoroheptanesulfonic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoroheptanoic acidPerfluoroheptanoic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluorohexanoic acidPerfluorohexanoic acid, a shorter-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluorononanoic acidPerfluorononanoic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoropentanesulfonic acid (PFPeS)Perfluoropentanesulfonic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoropentanoic acidPerfluoropentanoic acid, a shorter-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoroundecanoic acid (PFUnA)Perfluoroundecanoic acid, a longer-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| PFBAPerfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| 1,2,3-TCP | Not detected UG/LHighest single sampleSource water | 0.005 UG/LMCL | None detected |
| AtrazineA widely used agricultural herbicide that reaches water through runoff. | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Benzo(a)pyrene | Not detected UG/LHighest single sampleSource water | 0.2 UG/LMCL | None detected |
| Dalapon | Not detected UG/LHighest single sampleSource water | 200 UG/LMCL | None detected |
| Simazine | Not detected UG/LHighest single sampleSource water | 4 UG/LMCL | None detected |
Source: City of Cupertino, CA's 2026 Consumer Confidence Report — the annual drinking-water report every U.S. utility is required to publish. The numbers on this page are the utility's own. A water-quality report covers an entire service area, not a single address.
People also ask about City of Cupertino, CA's water
+Is City of Cupertino, CA tap water safe to drink in 2026?
Every one of the 50 contaminants measured in City of Cupertino, CA's 2026 Consumer Confidence Report is below its federal limit. "Safe" under the EPA's drinking-water standards is health-based, not aesthetic — but by those standards, no measured contaminant in this report exceeds its enforceable threshold. Individual health concerns (e.g. immunocompromised, infant, pregnancy) may warrant additional filtering regardless of compliance.
+What contaminants are in City of Cupertino, CA tap water?
50 contaminants were measured in City of Cupertino, CA's 2026 Consumer Confidence Report, spanning other, pfas ("forever chemicals"), and vocs & pesticides. 30 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Where does the data on this page come from?
Every value is transcribed from City of Cupertino, CA's 2026 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is City of Cupertino, CA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2026 report; a new report will replace it once the utility publishes its next annual update.
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