Community Water System · PWS MA4075000
Dennis Water District
Operator location South Dennis, Massachusetts - UCMR5 detected 2 PFAS compounds (lower-third PFAS panel (≤ 2 compounds)) on this PWS; SDWIS lists 44 violations and 65,000 people served.
- 65,000
- People served (this PWS) Larger third of systems
- 44
- EPA violations (this PWS) Middle third of systems
- 7
- Health-based (this PWS) Middle third by health-based share
- 2 PFAS
- UCMR5 (this PWS) Lower third of PFAS-detected systems
Dennis Water District standing, mid SDWIS violation third
UCMR5 detected 2 PFAS compounds - lower-third PFAS panel (≤ 2 compounds). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 16% is middle-third health share (≤ 23%). UCMR5: lower-third PFAS panel (≤ 2 compounds). Population rank #812 of 29,740 among systems serving 500+.
The verdict
Dennis Water District lands in the middle third by violation volume (44), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is large (65,000; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 16% (middle-third health share (≤ 23%)). UCMR5 detected 2 PFAS compounds (lower-third PFAS panel (≤ 2 compounds)).
- #812 of 29,740
- Population · /systems
- #21 of 418
- Population · MA
- 44
- Total EPA violations on record
- 16%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
2 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
Based on EPA SDWIS violation history and UCMR5 PFAS testing only, not water taste, odor, infrastructure age, or contaminants outside the federally tracked set.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 14,576
- County
- Barnstable
- School/Daycare
- No
- MCL Violations
- 7
- Monitoring Violations
- 34
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 7 | 2006 |
| TTHM | MR | 1 | 2008 |
| Total Haloacetic Acids (HAA5) | MR | 1 | 2008 |
| LASSO | MR | 1 | 2014 |
| 2,4-D | MR | 1 | 2014 |
| Endrin | MR | 1 | 2014 |
| Heptachlor epoxide | MR | 1 | 2014 |
| Heptachlor | MR | 1 | 2014 |
| Pentachlorophenol | MR | 1 | 2014 |
| Toxaphene | MR | 1 | 2014 |
| 2,4,5-TP | MR | 1 | 2014 |
| Methoxychlor | MR | 1 | 2014 |
| BHC-GAMMA | MR | 1 | 2014 |
| 1,2-DIBROMO-3-CHLOROPROPANE | MR | 1 | 2014 |
| Dalapon | MR | 1 | 2014 |
| Di(2-ethylhexyl) phthalate | MR | 1 | 2014 |
| Dinoseb | MR | 1 | 2014 |
| Endothall | MR | 1 | 2014 |
| Glyphosate | MR | 1 | 2014 |
| HEXACHLOROBENZENE | MR | 1 | 2014 |
| Hexachlorocyclopentadiene | MR | 1 | 2014 |
| OXAMYL | MR | 1 | 2014 |
| 2,3,7,8-TCDD | MR | 1 | 2014 |
| Picloram | MR | 1 | 2014 |
| Total Polychlorinated Biphenyls (PCB) | MR | 1 | 2014 |
| Chlordane | MR | 1 | 2014 |
| Simazine | MR | 1 | 2014 |
| Carbofuran | MR | 1 | 2014 |
| Diquat | MR | 1 | 2014 |
| ETHYLENE DIBROMIDE | MR | 1 | 2014 |
Violation Count vs. the National Corpus
Dennis Water District has 44 recorded EPA violations, 53% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 46% carry more. 16% of this system's own violations are health-based (7 of 44), and it ranks #812 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)
44 Around the middle fewer violations than 46% 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
How many violations vs. how serious, among peer systems
Dennis Water District plotted against 29 peer public water systems (500+ people served), by total violation count (x) and the share of those violations that are health-based (y). The crosshair sits at this sample's own median on each axis. A high violation count does not automatically mean a serious record: most monitoring and reporting violations are minor, not health-based.
Violation volume vs. health-based share
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 2 of 522 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFHpA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBA | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 4/9/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 4/9/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFOS | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeS | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOA | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| 4:2 FTS | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 4/9/2024 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFHpS | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 4/9/2024 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 4/9/2024 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 4/9/2024 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFEESA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFBS | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| ADONA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 4/9/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 4/9/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpS | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBS | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOS | 4/9/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTrDA | 4/9/2024 | <7.00 ppt | 7.00 ppt | Not Detected |
| NEtFOSAA | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 4/9/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTA | 4/9/2024 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFHxS | 4/9/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 4/9/2024 | <20.00 ppt | 20.00 ppt | Not Detected |
UCMR5 PFAS record for Dennis Water District
Open EPA SDWIS federal reports for PWS MA4075000 to cross-check UCMR5 detections and violation codes; state primacy agencies enforce the Safe Drinking Water Act locally.
Sources: EPA SDWIS · MassDEP, Drinking Water Program
Nationwide peers
44 violations · 65,000 served: nearest cross-state SDWIS matches.
Cross-state systems near this violation count
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 Dennis Water District
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Massachusetts compares on the same EPA violation measures. Massachusetts 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.
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.