Community Water System · PWS MA4197001
Siasconset Water Department
Operator location Nantucket, Massachusetts - upper-third violation load (> 74 violations) with 89 EPA violations; groundwater source; 3,000 served (PWS-level, not municipal population).
- 3,000
- People served (this PWS)
- 89
- EPA violations (this PWS)
- 8
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Siasconset Water Department standing, high SDWIS violation third
89 EPA SDWIS violations on record - upper-third violation load (> 74 violations). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 9% is middle-third health share (≤ 23%). Population rank #10,619 of 29,740 among systems serving 500+.
The verdict
Siasconset Water Department sits in the upper third of the sitemap cohort by violation count (89), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is mid-pack at 3,000 (mid served population (≤ 3,309)). Health-based share is 9% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- #10,619 of 29,740
- Population · /systems
- #274 of 418
- Population · MA
- 89
- Total EPA violations on record
- 9%
- 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
- 852
- County
- Nantucket
- School/Daycare
- No
- MCL Violations
- 8
- Monitoring Violations
- 72
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 8 | 2013 |
| Nitrate | MR | 3 | 2025 |
| Methoxychlor | MR | 2 | 2024 |
| BHC-GAMMA | MR | 2 | 2024 |
| Benzo(a)pyrene | MR | 2 | 2024 |
| Diquat | MR | 2 | 2024 |
| Dinoseb | MR | 2 | 2024 |
| Glyphosate | MR | 2 | 2024 |
| Hexachlorocyclopentadiene | MR | 2 | 2024 |
| OXAMYL | MR | 2 | 2024 |
| Picloram | MR | 2 | 2024 |
| Simazine | MR | 2 | 2024 |
| Carbofuran | MR | 2 | 2024 |
| Chlordane | MR | 2 | 2024 |
| Coliform (TCR) | MR | 2 | 2013 |
| Consumer Confidence Rule | Other | 2 | 2022 |
| 2,4-D | MR | 2 | 2024 |
| Heptachlor epoxide | MR | 2 | 2024 |
| Endrin | MR | 2 | 2024 |
| 1,2-DIBROMO-3-CHLOROPROPANE | MR | 2 | 2024 |
| Di(2-ethylhexyl) adipate | MR | 2 | 2024 |
| Di(2-ethylhexyl) phthalate | MR | 2 | 2024 |
| Endothall | MR | 2 | 2024 |
| 2,3,7,8-TCDD | MR | 2 | 2024 |
| Heptachlor | MR | 2 | 2024 |
| Dalapon | MR | 2 | 2024 |
| LASSO | MR | 2 | 2024 |
| Toxaphene | MR | 2 | 2024 |
| 2,4,5-TP | MR | 2 | 2024 |
| ETHYLENE DIBROMIDE | MR | 2 | 2024 |
Violation Count vs. the National Corpus
Siasconset Water Department has 89 recorded EPA violations, 71% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 29% carry more. 9% of this system's own violations are health-based (8 of 89), and it ranks #10,619 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)
89 Around the middle fewer violations than 29% 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
SDWIS compliance record for Siasconset Water Department
89 violations on record for MA4197001; use EPA SDWIS to confirm return-to-compliance dates and monitoring categories.
Sources: EPA SDWIS · MassDEP, Drinking Water Program
Nationwide peers
89 violations · 3,000 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 near this population served
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Siasconset Water Department
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.