01The verdict: is Thompson (T) water safe?
Thompson (T)'s drinking water has significant quality concerns based on EPA testing data. With a grade of D (45/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 19 water systems serve approximately 2,400 residents using surface water (rivers, lakes, or reservoirs).
Copper is over its legal limit
Measured at 1.40 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 1.8 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓107 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 ↓Thompson (T)'s drinking water received a grade of D (45 out of 100), indicating poor water quality. The city's 19 water systems serve approximately 2,400 residents using surface water.
Lead levels were measured at 1.8 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 563 violations on record, including 6 health-based violations. 62 remain unresolved.
Thompson (T) ranks #788 out of 810 cities in New York for water quality, placing it among the lowest-rated in the state. The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection. As a small community water system, Thompson (T) may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities. The system has seen 107 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
02What's in Thompson (T)'s water
Every contaminant flagged in Thompson (T), 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. | 1.8 | 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. | 1.40 | 1.3 | mg/L | Inorganic | Over Limit |
Cities ranked by 90th-percentile lead PF PFAS in New York
Cities ranked by compounds detected Cu Copper in New York
Cities ranked by 90th-percentile copper
03Thompson (T)'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 563 violations on record, including 6 health-based violations. 62 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 4 ppb since 1993. Latest reading: 0 ppb (2025) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
▼ Down 0 mg/L since 2005. The latest reading (1.4 mg/L, 2020) is over the action level. Sampled at higher-risk homes (90th percentile).
04Where Thompson (T)'s water comes from
Thompson (T)'s drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface Water
Rivers, lakes, or reservoirs — more exposed to runoff, agriculture, and seasonal swings than groundwater.
Local treatment
Multi-barrier treatment: coagulation, sedimentation, filtration, and disinfection to meet EPA standards.
19 systems
19 water systems, operated under private ownership.
2,400 people
Residents served across Thompson (T)'s service area.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards. These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge. The system is operated by private ownership and serves approximately 2,400 people through 19 water systems.
| System name | PWSID | Population | Source |
|---|---|---|---|
| EMERALD GREEN LAKE LOUISE MARIE WC | NY5203346 | 2,400 | Surface Water |
| ADELAAR WD | NY5230211 | 1,000 | Purchased Surface Water |
| KIAMESHA ARTESIAN SPRING WATER COMPANY | NY5203344 | 879 | Groundwater |
| KINNEBROOK ESTATES MHP | NY5201346 | 680 | Groundwater |
| TCFD - HARRIS | NY5225004 | 600 | Groundwater |
| PARKSIDE ESTATES | NY5230258 | 600 | Groundwater |
| HARRIS WOODS HOA | NY5221008 | 440 | Groundwater |
| WINDSOR HILL ESTATES | NY5230257 | 384 | Groundwater |
| KIAMESHA-ROUTE 42 WD | NY5220223 | 331 | Purchased Groundwater |
| FOREST PARK ESTATES | NY5230201 | 300 | Groundwater |
| CHARM ESTATES | NY5230263 | 280 | Groundwater |
| GREENTREE WATER COMPANY | NY5221394 | 184 | Groundwater |
| MELODY LAKE WD | NY5205653 | 150 | Groundwater |
| CRYSTAL WATER SUPPLY COMPANY | NY5220222 | 146 | Groundwater |
| COLD SPRING RD WD - THOMPSON | NY5220343 | 82 | Groundwater |
| SACKETT LAKE ESTATES | NY5230003 | 80 | Groundwater |
| LUCKY LAKE WD | NY5203356 | 60 | Groundwater |
| BROOKSIDE MOBILE HOME PARK | NY5201341 | 36 | Groundwater |
| DILLON FARM WD | NY5203350 | 30 | Groundwater |
Water bodies near Thompson (T)
As a surface-water system, these water bodies may directly influence Thompson (T)'s drinking water supply.
05Pressure on Thompson (T)'s watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
10 federal disaster declarations on record for Sullivan County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
06How Thompson (T) compares
Scores for nearby New York cities on one line, with the average marked.
dashed line = New York average (78/100)
Thompson (T) scores 45/100 — below the New York average of 78/100. Full New York rankings →
89 / 100CBrookhaven (T), NY
60.9 / 100AEast Hampton (T), NY
85.1 / 100BIslip (T), NY
71.8 / 100BSmithtown (T), NY
84.8 / 100BSouthampton (T), NY
78.8 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Thompson (T)'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 Thompson (T) alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Thompson (T), NY tap water safe to drink?
Thompson (T)'s water quality earned a grade of D (45/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #788 out of 810 cities tested in New York.
What contaminants are in Thompson (T)'s water?
Lead was measured at 1.8 ppb (90th percentile). 563 violations are on record.
How is Thompson (T)'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 Thompson (T)?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Thompson (T)'s water come from?
Thompson (T)'s water is sourced from Surface water. The city has 19 water systems serving approximately 2,400 residents.
What health violations has Thompson (T)'s water system had?
Thompson (T) has 6 health-based violations on record. The most recent violation was recorded in November 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 62 violations remain unresolved.
How does Thompson (T)'s water compare to other cities?
Thompson (T) ranks #788 out of 810 cities in New York (better than 3% of state cities) and #13975 out of 15382 cities nationally (9th percentile). The grade of D reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.