Water Systems with Most Violations (2026)

The worst offender has 113 total violations and exceedances. These water systems have accumulated the most health violations and contaminant exceedances on record.

#	Water System	State	Health Violations	Exceedances	Enforcement	Grade
1	City of Jackson Jackson, MS	Jackson, MS	100	13	101	F
2	Shreveport Water System Shreveport, LA	Shreveport, LA	76	25	57	F
3	Newark Water Department Newark, NJ	Newark, NJ	22	11	101	F
4	Springfield Water and Sewer Commission Springfield, MA	Springfield, MA	27	0	11	F
5	Tuscaloosa Water & Sewer Tuscaloosa, AL	Tuscaloosa, AL	6	5	16	F
6	Atlanta Atlanta, GA	Atlanta, GA	5	5	20	F
7	Sioux City Water Supply Sioux City, IA	Sioux City, IA	10	0	28	F
8	Mobile, Bd. Of W&s Comm. Of the City Of Mobile, AL	Mobile, AL	4	4	15	F
9	Bjw&sa (0720003) Okatie, SC	Okatie, SC	4	4	8	F
10	Liberty Utilities New York - Lynbrook Merrick, NY	Merrick, NY	6	0	10	F
11	Columbus Public Water System Columbus, OH	Columbus, OH	3	3	4	F
12	Las Cruces Municipal Water System Las Cruces, NM	Las Cruces, NM	6	0	27	F
13	Papillion, City Of Papillion, NE	Papillion, NE	3	3	11	F
14	Kearney, City Of Kearney, NE	Kearney, NE	3	3	5	F
15	Gilbert, Town Of Gilbert, AZ	Gilbert, AZ	3	2	101	F
16	Columbia City of (sc4010001) Columbia, SC	Columbia, SC	3	2	21	F
17	Clermont Public Water System Batavia, OH	Batavia, OH	2	2	12	F
18	Kalamazoo Kalamazoo, MI	Kalamazoo, MI	4	0	18	F
19	City of Baltimore Baltimore, MD	Baltimore, MD	3	1	38	F
20	Lowell Regional Water Utility Lowell, MA	Lowell, MA	3	0	4	F
21	Fort Wayne - 3 Rivers Filtration Plant Fort Wayne, IN	Fort Wayne, IN	3	0	7	F
22	Aqua Pa Main System Bryn Mawr, PA	Bryn Mawr, PA	2	0	40	F
23	Phoenix City Of Phoenix, AZ	Phoenix, AZ	2	0	12	D
24	Chandler City Of Chandler, AZ	Chandler, AZ	1	1	77	D
25	New Orleans Carrollton Water Works New Orleans, LA	New Orleans, LA	2	0	27	F
26	Roswell Municipal Water System Roswell, NM	Roswell, NM	2	0	11	F
27	Topeka, City Of Topeka, KS	Topeka, KS	1	1	12	D
28	Des Moines Water Works Des Moines, IA	Des Moines, IA	2	0	10	D
29	Salt Lake City Water System Salt Lake City, UT	Salt Lake City, UT	2	0	15	F
30	Glen Burnie-Broadneck Millersville, MD	Millersville, MD	1	1	12	D
31	Cocoa, City Of Cocoa, FL	Cocoa, FL	1	0	11	C
32	Mcwa Rochester, NY	Rochester, NY	1	0	3	B
33	Rochester City Rochester, NY	Rochester, NY	1	0	3	B
34	Cicero Cicero, IL	Cicero, IL	1	0	29	C
35	Veolia Water New Jersey Hackensack Haworth, NJ	Haworth, NJ	1	0	12	C
36	Jersey City Mua Hoboken, NJ	Hoboken, NJ	1	0	22	C
37	Boston Water and Sewer Commission (mwra) Boston, MA	Boston, MA	1	0	1	B
38	Kansas City Pws Kansas City, MO	Kansas City, MO	1	0	4	C
39	Madison Water Utility Madison, WI	Madison, WI	1	0	1	B
40	Portland Water Bureau Portland, OR	Portland, OR	1	0	4	C
41	Norman Utilities Authority Norman, OK	Norman, OK	1	0	11	C
42	Santa Fe Water System (city Of) Santa Fe, NM	Santa Fe, NM	1	0	28	D
43	Fort Smith Water Utilities Fort Smith, AR	Fort Smith, AR	1	0	4	C
44	East Bay MUD Oakland, CA	Oakland, CA	0	0	0	A
45	City of Fresno Fresno, CA	Fresno, CA	0	0	2	A
46	Alameda County Water District Fremont, CA	Fremont, CA	0	0	0	A
47	CWS - Bakersfield San Jose, CA	San Jose, CA	0	0	0	A
48	Contra Costa Water District Concord, CA	Concord, CA	0	0	0	A
49	San Antonio Water System San Antonio, TX	San Antonio, TX	0	0	11	B
50	Dallas Water Utility Dallas, TX	Dallas, TX	0	0	0	A

Frequently Asked Questions

Health-based violations occur when a contaminant level exceeds the EPA Maximum Contaminant Level (MCL) or when required treatment techniques are not followed. These are the most serious type of drinking water violation.

This ranking includes both active and resolved violations. Check individual system pages for current violation status. Many systems have taken corrective action since violations were recorded.

Request your system's annual Consumer Confidence Report (CCR) for current water quality data. Consider an NSF-certified water filter for extra protection, especially if violations are recent or ongoing.