78666
San Marcos, TX
Hays County · Austin-Round Rock-San Marcos, TX metro area
CITY OF SAN MARCOS
Is tap water in San Marcos CCD (78666) safe to drink?
Source: Official EPA UCMR5 federal monitoring data. Last tested October 2025.
City:
CDP:
Townships:
- San Marcos CCD, TX
- Northeast Guadalupe CCD, TX
- Dripping Springs-Wimberley CCD, TX
Neighborhood:
- San Marcos
The short answer for San Marcos CCD (78666)
San Marcos tap water has 2 contaminants above EPA guidelines, including PFPeA at 1.2× the limit (tested August 2024). See the full compound-by-compound breakdown and filter recommendations.
The health risk for San Marcos
PFAS ('forever chemicals') have been detected above EPA limits in this water system's most recent tests. These synthetic chemicals do not break down in the body and are linked to a range of health effects. A certified filter is strongly recommended.
- PFPeA above limit.
PFPeA concentration (µg/L)
August 2024
0 µg/L
0.003 µg/L
0.01 µg/L
0.004 µg/L
Detected
µg/L
0.003 µg/L
EPA limit
guideline
23% above limit
Comparison
vs. guideline
EPA limit: 0.003 µg/L | Your water: 0.004 µg/L
Certified Filters for San Marcos Tap Water
PFPeA (a PFAS 'forever chemical') was detected above EPA limits. These filters are independently certified to reduce common drinking-water contaminants.
Pitcher filter
Epic Pure XP Water Filter Pitcher
NSF-certified dual-layer filtration reduces 70+ contaminants including PFAS, lead, chlorine, microplastics, and bacteria.
NSF/ANSI 42, 53, 401 & P473Removes 99.99% PFASMade in USABPA-free
PFAS detected in 78666 · What you can do
Here's what actually removes PFAS from your water
The right filter eliminates PFAS at the tap. But not all filters do - and the type you choose matters for your home.
Common pitchers like Brita do not remove PFAS. You need a filter independently certified to NSF P473 (for pitcher filters) or NSF/ANSI 58 (for reverse osmosis systems). All three options below carry the relevant certification.
Certified PFAS filter types - how they differ
Certified Pitcher
Removes PFAS (99%+)
No installation, works today
Lowest upfront cost (~$70)
Must refill manually
Filters only what you pour in - not cooking water
Reverse Osmosis More complete
Removes PFAS + lead, arsenic, nitrates & more
Always-on - no refilling ever
Noticeably better tasting water
Filters drinking & cooking water automatically
Higher upfront cost ($200-$400)
Choose your option
Most elevated compounds
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| PFPeA Tested: August 2024 · SWTP |
0.004 µg/L | 0.003 µg/L | 23% above limit |
| PFPeA Tested: August 2024 · Soyar |
0.004 µg/L | 0.003 µg/L | 20% above limit |
| 6:2 FTS Tested: May 2025 · Hays Caldwell |
0.005 µg/L | 0.005 µg/L | 100% of limit |
| 6:2 FTS Tested: May 2024 · McCarty Ln |
0.005 µg/L | 0.005 µg/L | 100% of limit |
| lithium Tested: August 2025 · Post Rd |
9.800 µg/L | 10 µg/L | 98% of limit |
View all tested compounds
Soyar · Tested: August 2024
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| PFPeA | 0.004 µg/L | 0.003 µg/L | 20% above limit |
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
SWTP · Tested: August 2024
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| PFPeA | 0.004 µg/L | 0.003 µg/L | 23% above limit |
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Comanche · Tested: August 2024
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
CRWA Hays Caldwell Connection · Tested: Multiple dates
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Great Oaks · Tested: August 2024
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Hays Caldwell · Tested: May 2025
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| 6:2 FTS | 0.005 µg/L | 0.005 µg/L | 100% of limit |
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Kingswood · Tested: August 2024
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
McCarty Ln · Tested: May 2024
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| 6:2 FTS | 0.005 µg/L | 0.005 µg/L | 100% of limit |
| PFHxS | 0.003 µg/L | 0.004 µg/L | 85% of limit |
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Nelson (GWM-2) · Tested: February 2025
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Nelson Well #2 · Tested: February 2025
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Post Rd · Tested: August 2025
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | 9.800 µg/L | 10 µg/L | 98% of limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Springlake · Tested: August 2024
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Springs Hill Interconnect · Tested: February 2025
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Treatment Plant · Tested: April 2025
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | 9.500 µg/L | 10 µg/L | 95% of limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Windmill CRWA · Tested: May 2025
| Compound | Measurement | EPA Limit | Comparison |
|---|---|---|---|
| lithium | <9.000 µg/L | 10 µg/L | Below limit |
| PFHxS | <0.003 µg/L | 0.004 µg/L | Below limit |
| HFPO-DA | <0.005 µg/L | 0.01 µg/L | Below limit |
| PFNA | <0.004 µg/L | 0.01 µg/L | Below limit |
| PFHxA | <0.003 µg/L | 3 µg/L | Below limit |
| PFBA | <0.005 µg/L | 6 µg/L | Below limit |
| 11Cl-PF3OUdS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 4:2 FTS | <0.003 µg/L | 0.003 µg/L | Below limit |
| 6:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 8:2 FTS | <0.005 µg/L | 0.005 µg/L | Below limit |
| 9Cl-PF3ONS | <0.002 µg/L | 0.002 µg/L | Below limit |
| ADONA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFBS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFDoA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFHpS | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFOA | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFOS | <0.004 µg/L | 0.004 µg/L | Below limit |
| PFPeA | <0.003 µg/L | 0.003 µg/L | Below limit |
| PFTrDA | <0.007 µg/L | 0.007 µg/L | Below limit |
| PFUnA | <0.002 µg/L | 0.002 µg/L | Below limit |
Water utilities serving ZIP 78666
Service area boundaries are approximate and based on state filings or modeled estimates. Contact your utility to confirm exact service at a specific address.
- CITY OF SAN MARCOSAction advised
Modeled boundaries are shown with a dashed outline.
Frequently Asked Questions about ZIP 78666 Tap Water
What contaminants are above EPA limits in ZIP 78666?
ZIP 78666 has 2 contaminants above EPA health guidelines in the latest available data, including PFPeA at 1.2x the EPA guideline. The full table on this page lists every tested compound and its measured level.
Will boiling ZIP 78666 tap water remove PFPeA?
No. Boiling does not remove PFAS, and the compounds can actually become more concentrated as water evaporates. To reduce PFAS at home, use a filter independently certified to NSF/ANSI P473 (activated-carbon pitcher or under-sink) or NSF/ANSI 58 (reverse osmosis).
Do basic pitcher filters remove PFPeA?
Most basic pitcher filters are only certified to NSF/ANSI 42 or 53, which do not cover PFAS. Look for a filter independently certified to NSF/ANSI P473 (activated-carbon pitcher or under-sink) or NSF/ANSI 58 (reverse osmosis) on the spec sheet.
Who provides tap water in ZIP 78666?
Public records identify CITY OF SAN MARCOS as a primary water system associated with ZIP 78666. Service boundaries can vary by address, so confirm exact service with the utility.
When was ZIP 78666 tap water last tested?
The most recent test date used in this report is October 2025. EnviroClarity last refreshed this page on 2026-05-05.
Where can I find the official water quality report for ZIP 78666?
Every U.S. public water system is required to publish an annual Consumer Confidence Report (CCR). Contact CITY OF SAN MARCOS or visit their website for the latest official report covering ZIP 78666. The EPA also maintains a national CCR locator.
Check another ZIP code
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Data reflects publicly reported utility records from EPA datasets and local utility disclosures. This information is educational and not medical advice.