Community Water System · PWS CT0419221
31 Grist Mill RD
Operator location Old Lyme, Connecticut - smaller served population (≤ 999) at 30 people served; 636 SDWIS violations on record from groundwater sources.
- 30
- People served (this PWS)
- 636
- EPA violations (this PWS)
- 28
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
31 Grist Mill RD standing, high SDWIS violation third
30 people served (SDWIS) - smaller served population (≤ 999). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 4% is middle-third health share (≤ 23%).
The verdict
31 Grist Mill RD sits in the upper third of the sitemap cohort by violation count (636), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (30; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 4% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- 636
- Total EPA violations on record
- 4%
- Health-based (MCL / treatment failure)
- 30
- People served by this PWS (SDWIS)
- N/A
- PFAS compounds detected (UCMR5)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Private
- Connections
- 14
- County
- Middlesex
- School/Daycare
- No
- MCL Violations
- 20
- Monitoring Violations
- 551
- Treatment Tech Violations
- 8
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| E. COLI | MR | 79 | 2021 |
| Revised Total Coliform Rule | MON | 32 | 2021 |
| Public Notice | Other | 30 | 2020 |
| Lead and Copper Rule | MR | 16 | 2023 |
| Coliform (TCR) | MCL | 12 | 2015 |
| Combined Radium (-226 and -228) | MR | 12 | 2021 |
| Tritium | MR | 12 | 2017 |
| Arsenic | MR | 9 | 2017 |
| Barium | MR | 9 | 2017 |
| Chromium | MR | 9 | 2017 |
| Fluoride | MR | 9 | 2017 |
| Mercury | MR | 9 | 2017 |
| Nickel | MR | 9 | 2017 |
| Antimony, Total | MR | 9 | 2017 |
| Beryllium, Total | MR | 9 | 2017 |
| Thallium, Total | MR | 9 | 2017 |
| Selenium | MR | 9 | 2017 |
| Cadmium | MR | 9 | 2017 |
| CYANIDE | MR | 9 | 2017 |
| Coliform (TCR) | MR | 8 | 2015 |
| Methoxychlor | MR | 8 | 2017 |
| Dalapon | MR | 8 | 2017 |
| Simazine | MR | 8 | 2017 |
| Di(2-ethylhexyl) phthalate | MR | 8 | 2017 |
| Picloram | MR | 8 | 2017 |
| Hexachlorocyclopentadiene | MR | 8 | 2017 |
| Aldicarb sulfoxide | MR | 8 | 2017 |
| Aldicarb sulfone | MR | 8 | 2017 |
| Carbofuran | MR | 8 | 2017 |
| Atrazine | MR | 8 | 2017 |
Violation Count vs. the National Corpus
31 Grist Mill RD has 636 recorded EPA violations, 97% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 3% carry more. 4% of this system's own violations are health-based (28 of 636), and it ranks unranked by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
636 Higher than most more violations than 97% 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
Population served record for 31 Grist Mill RD
EPA SDWIS lists 30 people served and 14 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS
Nationwide peers
636 violations · 30 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.
What to do with 31 Grist Mill RD
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Connecticut compares on the same EPA violation measures. Connecticut 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.