countyscore

Water Quality · Illinois

Best Water Quality Counties in Illinois 2026

Ranked by EPA drinking water health violations.

Top 10 — Water Quality in Illinois

Score reflects water quality only — not overall county quality.

1Alexander County, IL
86
2Boone County, IL
86
3Brown County, IL
86
4Clay County, IL
86
5Edwards County, IL
86
6Gallatin County, IL
86
7Henderson County, IL
86
8Jasper County, IL
86
9Jefferson County, IL
86
10Jersey County, IL
86

All Illinois Counties — Water Quality Rankings

102 counties ranked by water quality score. Overall Score shown for context.

#CountyWater Quality ScoreOverall Score
1Alexander County, IL
86
62.2
2Boone County, IL
86
43.7
3Brown County, IL
86
69.5
4Clay County, IL
86
55.8
5Edwards County, IL
86
66.7
6Gallatin County, IL
86
67.6
7Henderson County, IL
86
61.7
8Jasper County, IL
86
59.7
9Jefferson County, IL
86
51.7
10Jersey County, IL
86
53.4
11Marion County, IL
86
46.7
12Moultrie County, IL
86
58.4
13Washington County, IL
86
63.7
14DuPage County, IL
71.3
54
15Cook County, IL
70.8
30.3
16Kane County, IL
70.1
47.1
17Kendall County, IL
69.3
38.6
18Coles County, IL
68.4
57.4
19Peoria County, IL
68.2
31
20Franklin County, IL
67.1
55.9
21McHenry County, IL
67.1
52.3
22DeKalb County, IL
66
37
23Stephenson County, IL
65.8
45.6
24Lake County, IL
65.3
47.2
25Will County, IL
65.1
50.3
26Champaign County, IL
63.5
34.4
27Madison County, IL
63.4
38.1
28Crawford County, IL
62.8
52.5
29Tazewell County, IL
62.6
42.5
30St. Clair County, IL
61
41.3
31Ogle County, IL
60.8
38.7
32Pike County, IL
60.4
55.6
33White County, IL
59
62.5
34Monroe County, IL
58.7
58.5
35Lawrence County, IL
58.3
55.7
36Montgomery County, IL
58.3
45.9
37Winnebago County, IL
57.1
42.4
38De Witt County, IL
56.9
47.8
39Cass County, IL
56.8
57.4
40Wabash County, IL
55.4
55.3
41Mercer County, IL
55.3
63.1
42Vermilion County, IL
54.5
35.5
43Knox County, IL
54.4
56
44Rock Island County, IL
53.1
36.7
45Hamilton County, IL
52.8
68.6
46Whiteside County, IL
52.3
46.2
47Warren County, IL
50.1
52.4
48Carroll County, IL
48.9
60.6
49Ford County, IL
48.6
53.8
50Adams County, IL
46.6
54.7
51Sangamon County, IL
46
33.4
52Mason County, IL
44.4
52.8
53Jo Daviess County, IL
43.2
60.8
54Macon County, IL
42.8
34.6
55Massac County, IL
41.8
43.2
56Logan County, IL
41.6
51.6
57Grundy County, IL
41.2
44.8
58Pulaski County, IL
41
62.9
59Calhoun County, IL
40.7
63
60Saline County, IL
40.7
56.8
61Clark County, IL
39.8
55.5
62Kankakee County, IL
39.6
48
63McLean County, IL
37.2
48.1
64Shelby County, IL
37.1
60.9
65Cumberland County, IL
36.3
62
66Greene County, IL
35.3
60.2
67Livingston County, IL
34.4
51.6
68Hardin County, IL
34.2
70.7
69Piatt County, IL
33.4
54.9
70Edgar County, IL
32
59.8
71Williamson County, IL
31.6
49.9
72Stark County, IL
31.5
61.1
73Clinton County, IL
31
52
74Marshall County, IL
30.4
54.9
75Henry County, IL
30.3
50.3
76Randolph County, IL
30
58.7
77Schuyler County, IL
30
58.3
78Perry County, IL
29.7
59.8
79Bureau County, IL
29.5
45.7
80Fayette County, IL
29.5
53.8
81Douglas County, IL
29.3
55.6
82Menard County, IL
28.3
59.2
83Jackson County, IL
27.5
36
84Iroquois County, IL
26.6
50.3
85Richland County, IL
26.4
51.4
86Morgan County, IL
25
43.1
87Hancock County, IL
24.7
58.6
88Putnam County, IL
22.6
59.3
89Woodford County, IL
21
58.8
90Lee County, IL
20.9
51.7
91Christian County, IL
20.7
55.3
92McDonough County, IL
20.3
56.3
93Effingham County, IL
19.6
49.7
94Fulton County, IL
19.5
53.9
95Macoupin County, IL
16.5
52.5
96Johnson County, IL
15.8
67.7
97Wayne County, IL
15.4
52.6
98LaSalle County, IL
15.3
40.6
99Pope County, IL
12.9
67.4
100Bond County, IL
11.9
55.2
101Scott County, IL
11.9
68
102Union County, IL
9.7
57.4

Explore More

Best overall counties in IllinoisFull Water Quality data on WaterByCounty