25 Cities With the Most Chloroform in Drinking Water (2026)
By Echo Water Research Team8 min read
25
Cities Analyzed
203
Total Contaminants Above Guidelines
40,241
People Affected
We analyzed tap water quality data for hundreds of cities across the United States to identify those with the highest levels of chloroform. This ranking is based on 2026 data from the EPA and EWG databases.
Chloroform is a contaminant of growing concern in drinking water. The cities below have the highest detected levels based on the most recent testing data available.
Methodology: Cities are ranked by the detected level of chloroform (descending), showing those with the highest concentrations first. Data sourced from the EPA Safe Drinking Water
Information System (SDWIS) and the Environmental Working Group (EWG) Tap Water Database.
Only cities with available EWG testing data are included.
Plattsburgh has chloroform detected at 80.90 ppb. 21 total contaminants were found in the water supply.
What We Found: Key Patterns
The most frequently detected contaminants exceeding health guidelines across these cities are Bromodichloromethane, Chloroform, Dichloroacetic acid. These appear repeatedly across different water systems and regions.
Geographically, the states most represented in this ranking are Oklahoma (12), Alaska (3), Louisiana (3). Regional water sources, industrial activity, and agricultural runoff all contribute to local water quality variation.
Across all ranked cities, 203 contaminant readings exceed EWG health guidelines, but only 41 exceed EPA legal limits. This gap of 162 highlights how legal standards may not fully protect public health — EPA limits haven't been updated for many contaminants in decades.
Full Rankings Table
Rank
City
State
Detected
Above Guidelines
Above Legal
People Served
1
Wanette
OK
12
8
2
402
2
Asher
OK
11
8
2
375
3
Maysville
OK
14
10
2
0
4
Statenville
GA
10
9
2
0
5
Chalkyitsik
AK
9
6
2
75
6
Nome
TX
21
10
2
0
7
Pittsburg
OK
10
7
2
280
8
Provencal
LA
13
8
2
1,032
9
Antlers
OK
11
7
2
4,825
10
Mount Erie
IL
15
11
2
0
11
Tullos
LA
16
10
2
792
12
Boswell
OK
14
8
1
850
13
Dixon
WY
13
9
2
0
14
Fairfax
OK
13
9
1
1,555
15
Rye
CO
12
6
2
745
16
Albion
OK
9
6
1
0
17
Keota
OK
10
7
1
564
18
Kotzebue
AK
11
9
2
0
19
Whitesboro
OK
12
7
1
1,643
20
Sikes
LA
14
8
2
639
21
Chester
MA
13
6
1
0
22
Galena
AK
8
6
2
470
23
Nashoba
OK
8
7
1
725
24
Avant
OK
10
9
2
361
25
Plattsburgh
NY
21
12
0
24,908
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What cities have the highest levels of chloroform?
Our analysis of 2026 data identified the cities with the highest detected levels of chloroform. See the full ranking above.
Is chloroform dangerous in drinking water?
Chloroform has known health risks at elevated levels. The EWG sets health guidelines that are often stricter than EPA legal limits to account for the latest research on long-term exposure.
How do I remove chloroform from my water?
Reverse osmosis (RO) systems are the most effective at removing a wide range of contaminants. Check the specific contaminant details for recommended filtration technology.
What is the EPA legal limit for chloroform?
EPA legal limits vary by contaminant and may differ from EWG health guidelines. See individual city reports for specific legal limit comparisons.
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: September 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
