Head-to-head water quality
Dallas, TX vs Smithtown (T), NY
Side-by-side water quality comparison: Dallas (Grade F) vs Smithtown (T) (Grade B-). Lead, PFAS, violations, and source-water contamination
Score breakdown
Each factor is shown as raw points (out of the maximum). Higher = better.
Factor
Dallas
Smithtown (T)
Better
Violations subscore / 45
0.0
31.9
Smithtown (T)
Lead/Copper subscore / 20
20.0
20.0
Tie
Contaminant subscore / 20
7.2
6.8
Dallas
Compliance subscore / 10
5.0
8.0
Smithtown (T)
Source subscore / 5
4.0
5.0
Smithtown (T)
Lead & copper at the tap
Lead and Copper Rule (LCR) 90th-percentile readings — the value that 10% of sampled homes exceed.
Factor
Dallas
Smithtown (T)
Better
Lead 90th-percentile (latest) · EPA action level: 15 µg/L
0.0 µg/L
0.0 µg/L
Tie
Copper 90th-percentile (latest) · EPA action level: 1.3 mg/L
—
—
—
PFAS — "forever chemicals"
UCMR 5 testing, 2023–2025. Federal MCLs: PFOA + PFOS = 4 ng/L; HFPO-DA = 10 ng/L.
Factor
Dallas
Smithtown (T)
Better
PFAS analytes detected
9 of 30
10 of 30
Dallas
PFAS exceeds federal MCL
Yes
Yes
Tie
PFAS hazard index · Sum of (max/MCL) across detected analytes; > 1 indicates exceedance
2.85
5.97
Dallas
Violation history
SDWA enforcement actions — fewer is better.
Factor
Dallas
Smithtown (T)
Better
Violations (last 5 years)
153
3
Smithtown (T)
Health-based violations (total)
102
7
Smithtown (T)
Unresolved violations
221
8
Smithtown (T)
Other contaminants tested
UCMR rounds 1–4 + UCMR 5 lithium. Maxima where data exists; "—" means not tested.
Factor
Dallas
Smithtown (T)
Better
Chromium-6 (max)
0.58 µg/L
5.59 µg/L
Dallas
HAA5 (avg)
7.52 µg/L
0.80 µg/L
Smithtown (T)
Manganese (max)
3.40 µg/L
176.80 µg/L
Dallas
Strontium (max)
456.00 µg/L
169.00 µg/L
Smithtown (T)
1,4-Dioxane (max)
0.10 µg/L
4.34 µg/L
Dallas
NDMA (max)
6.20 ng/L
13.43 ng/L
Dallas
Perchlorate (max)
—
12.10 µg/L
Smithtown (T)
Vanadium (max)
2.70 µg/L
6.97 µg/L
Dallas
Chlorate (max)
214.00 µg/L
386.00 µg/L
Dallas
Molybdenum (max)
3.16 µg/L
1.18 µg/L
Smithtown (T)
Industrial proximity
Superfund National Priorities List + Toxic Release Inventory facilities within 10 miles of the city centroid.
Factor
Dallas
Smithtown (T)
Better
Superfund sites within 10 mi
2
0
Smithtown (T)
TRI lbs to surface water within 10 mi (2023)
71
0
Smithtown (T)
System size & source
Factor
Dallas
Smithtown (T)
Population served
1.4M
1.1M
—
Water source
Surface water
Groundwater
—
Number of water systems
32
3
—
See the full reports
Frequently asked
Which has better water — Dallas or Smithtown (T)?
Smithtown (T), NY scores higher (71.8 vs 36.2) on WaterVerge's 100-point methodology, earning a Grade B- compared to Dallas's Grade F. The score combines violation history, lead and copper levels, contaminant testing, monitoring compliance, and source-water type.
How is the WaterVerge water quality score calculated?
The grade combines five subscores: violation history (45 pts, weighted by recency and health-based severity), lead/copper 90th-percentile vs EPA action levels (20 pts), contaminant testing including PFAS, chromium-6, HAA5, NDMA, perchlorate, and Superfund/TRI proximity (20 pts), monitoring compliance (10 pts), and water-source-type risk (5 pts). Full methodology at /about/methodology.
Where does this water quality data come from?
From the EPA's public records: the SDWIS bulk download (violations + system info), UCMR rounds 1–5 (unregulated contaminant testing including PFAS, chromium-6, HAA5, NDMA, perchlorate, vanadium, lithium), the EPA Toxic Release Inventory (industrial polluters), the Superfund National Priorities List, the USGS Powell Domestic-Well Database (private-well chemistry), and the CDC Community Water Fluoridation system. Data is refreshed quarterly.