Community Water System · PWS PR0003303
San Sebastian
Operator location San Sebastian, Puerto Rico - 51% of 250 violations are health-based (upper-third health share (> 23%)); surface water source; 24,449 served per SDWIS.
- 24,449
- People served (this PWS)
- 250
- EPA violations (this PWS)
- 128
- Health-based (this PWS)
- No PFAS
- UCMR5 (this PWS)
San Sebastian standing, high SDWIS violation third
51% of 250 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 51% is upper-third health share (> 23%). UCMR5: UCMR5 tested, none detected. Population rank #2,284 of 29,740 among systems serving 500+.
The verdict
San Sebastian sits in the upper third of the sitemap cohort by violation count (250), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is large (24,449; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 51% - most of this ledger is MCL or treatment-technique exceedance. UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #2,284 of 29,740
- Population · /systems
- #30 of 235
- Population · PR
- 250
- Total EPA violations on record
- 51%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 9,157
- County
- San Sebastian Municipio
- School/Daycare
- No
- MCL Violations
- 64
- Monitoring Violations
- 100
- Treatment Tech Violations
- 64
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Total Haloacetic Acids (HAA5) | MCL | 39 | 2020 |
| Surface Water Treatment Rule | TT | 38 | 2001 |
| Interim Enhanced Surface Water Treatment Rule | TT | 17 | 2011 |
| Cryptosporidium | MR | 17 | 2018 |
| TTHM | MCL | 17 | 2016 |
| Turbidity | MR | 15 | 2018 |
| E. COLI | MR | 15 | 2018 |
| Coliform (TCR) | MR | 9 | 2013 |
| CARBON, TOTAL | TT | 9 | 2015 |
| Coliform (TCR) | MCL | 8 | 2016 |
| Lead and Copper Rule | MR | 7 | 2016 |
| Consumer Confidence Rule | Other | 4 | 2020 |
| OXAMYL | MR | 2 | 2015 |
| Chromium | MR | 2 | 1984 |
| Mercury | MR | 2 | 1984 |
| Nitrate | MR | 2 | 1984 |
| Arsenic | MR | 2 | 1984 |
| Selenium | MR | 2 | 1984 |
| Cadmium | MR | 2 | 1984 |
| Fluoride | MR | 2 | 1984 |
| Nitrite | MR | 2 | 2005 |
| Barium | MR | 2 | 1984 |
| Carbofuran | MR | 2 | 2015 |
| TTHM | MR | 1 | 2005 |
| ETHYLENE DIBROMIDE | MR | 1 | 2005 |
| Chlordane | MR | 1 | 2009 |
| Endrin | MR | 1 | 2009 |
| BHC-GAMMA | MR | 1 | 2009 |
| Heptachlor epoxide | MR | 1 | 2009 |
| HEXACHLOROBENZENE | MR | 1 | 2009 |
Violation Count vs. the National Corpus
San Sebastian has 250 recorded EPA violations, 88% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 12% carry more. 51% of this system's own violations are health-based (128 of 250), and it ranks #2,284 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
250 Higher than most more violations than 88% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 116 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFMBA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 9/26/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFDoA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 9/26/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFEESA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 9/26/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 9/26/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHpA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 9/26/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFOA | 9/26/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 9/26/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 9/26/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFNA | 9/26/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 4:2 FTS | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| ADONA | 9/26/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBA | 9/26/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 9/26/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 9Cl-PF3ONS | 9/26/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| HFPO-DA | 9/26/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 9/26/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| NEtFOSAA | 9/26/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTA | 9/26/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| NMeFOSAA | 9/26/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFBS | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 6/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 6/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NFDHA | 6/27/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFEESA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 6/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 6/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 6/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 9Cl-PF3ONS | 6/27/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| ADONA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 6/27/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 6/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 6/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 6/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
Health-based violations on San Sebastian
128 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for PR0003303.
Sources: EPA SDWIS
Nationwide peers
250 violations · 24,449 served: nearest cross-state SDWIS matches.
Cross-state systems with comparable violation load
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with San Sebastian
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Puerto Rico compares on the same EPA violation measures. Puerto Rico systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.