01The verdict: is Old Lyme water safe?
Old Lyme's drinking water has significant quality concerns based on EPA testing data. With a grade of D (46/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 11 water systems serve approximately 541 residents using groundwater (wells).
Copper is over its legal limit
Measured at 2.81 mg/L against the EPA Action Level of 1.3 mg/L. The ledger below shows how far over — and which filter removes it.
See the measurement ↓Lead is well under the limit
90th-percentile lead is 0.0 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓93 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Old Lyme's drinking water received a grade of D (46 out of 100), indicating poor water quality. The city's 11 water systems serve approximately 541 residents using groundwater.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 778 violations on record, including 42 health-based violations. 132 remain unresolved.
Old Lyme ranks #100 out of 129 cities in Connecticut for water quality, placing it among the lowest-rated in the state. Old Lyme relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff. As a small community water system, Old Lyme may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities. The system has seen 93 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
02What's in Old Lyme's water
Every contaminant flagged in Old Lyme, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Over Limit — EPA Action Level: 1.3 mg/L
Exceeds the EPA action level. Copper leaches from household plumbing — flush taps for 30 seconds before drinking, and consider a certified filter.Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 2.81 | 1.3 | mg/L | Inorganic | Over Limit |
Cities ranked by 90th-percentile lead PF PFAS in Connecticut
Cities ranked by compounds detected Cu Copper in Connecticut
Cities ranked by 90th-percentile copper
03Old Lyme's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 778 violations on record, including 42 health-based violations. 132 remain unresolved.
1 of the last ten years was clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 20 ppb since 1993. Latest reading: 0 ppb (2025) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
▲ Up 1.1 mg/L since 1993. The latest reading (2.8 mg/L, 2021) is over the action level. Sampled at higher-risk homes (90th percentile).
04Where Old Lyme's water comes from
Old Lyme's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
11 systems
11 water systems, operated under private ownership.
541 people
Residents served across Old Lyme's service area.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals. Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds. The system is operated by private ownership and serves approximately 541 people through 11 water systems.
| System name | PWSID | Population | Source |
|---|---|---|---|
| CTWC - SHORELINE REGION-SOUND VIEW | CT1050732 | 3,028 | Groundwater |
| CTWC - SHORELINE REGION-POINT O WOODS | CT1050752 | 1,068 | Groundwater |
| CHADWICK HOMEOWNERS ASSN., INC. | CT1050011 | 292 | Groundwater |
| WHISPERING PINES MHP | GA3050030 | 94 | Groundwater |
| RYE FIELD MANOR ELDERLY HOUSING | CT1056241 | 78 | Groundwater |
| MILE CREEK APARTMENTS | CT1050131 | 60 | Groundwater |
| LYMEWOOD ELDERLY HOUSING | CT1056221 | 50 | Groundwater |
| LYME ACADEMY APARTMENTS,LLC | CT1059251 | 48 | Groundwater |
| LAUREL HEIGHTS ASSOCIATION, INC. | CT1056231 | 45 | Groundwater |
| LYME REGIS, INC. | CT1050141 | 32 | Groundwater |
| BOXWOOD CONDOMINIUM ASSOCIATION | CT1051011 | 28 | Groundwater |
Water bodies near Old Lyme
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05How Old Lyme compares
Scores for nearby Connecticut cities on one line, with the average marked.
dashed line = Connecticut average (72/100)
Old Lyme scores 46/100 — below the Connecticut average of 72/100. It outscores 2 of 10 nearby cities. Full Connecticut rankings →
82.4 / 100CBethany, CT
55.8 / 100ABranford, CT
85.4 / 100FCheshire, CT
35.5 / 100BDerby, CT
80.2 / 100AEast Haven, CT
85.4 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
06What to do at home
Steps matched to what testing actually found in Old Lyme's water — not generic advice.
Filter drinking & cooking water
NSF-certified water filter. Copper exceeds the EPA action level of 1.3 mg/L
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Old Lyme alerts
We refresh EPA data monthly and surface new violations, advisories, and boil-water notices for your county on this page.
All water alerts →Frequently asked questions
Is Old Lyme, CT tap water safe to drink?
Old Lyme's water quality earned a grade of D (46/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #100 out of 129 cities tested in Connecticut.
What contaminants are in Old Lyme's water?
Lead was measured at 0.0 ppb (90th percentile). 778 violations are on record.
How is Old Lyme's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Old Lyme?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Old Lyme's water come from?
Old Lyme's water is sourced from Groundwater. The city has 11 water systems serving approximately 541 residents.
What health violations has Old Lyme's water system had?
Old Lyme has 42 health-based violations on record. The most recent violation was recorded in August 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 132 violations remain unresolved.
Is Old Lyme's groundwater at risk of contamination?
Old Lyme uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 778 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Old Lyme's water compare to other cities?
Old Lyme ranks #100 out of 129 cities in Connecticut (better than 22% of state cities) and #13796 out of 15382 cities nationally (10th percentile). The grade of D reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.