Contaminants and rules in Indiana water systems

81 different rules and contaminants appear in the past three years of violation records for Indiana's 3,935 active public water systems. The tables show how many systems each one affected and how many of those violations are still unresolved. Most entries are monitoring, reporting, or notification lapses rather than confirmed contamination.

Microbial

Bacteria and the rules that test for them. Health-based when a sample is positive.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
Revised Total Coliform Rule (RTCR)	8000	1,320	34%	439
E. coli (Escherichia coli)	3014	71	2%	71

Inorganic Chemical

Naturally occurring or from fertilizer and industry. Each has a maximum contaminant level.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
Nitrate	1040	462	12%	21
Arsenic	1005	57	1%	7
Nitrite	1041	53	1%	0
Barium	1010	29	1%	0
Cadmium	1015	29	1%	0
Chromium	1020	29	1%	0
Cyanide	1024	29	1%	0
Mercury	1035	29	1%	0
Nickel	1036	29	1%	0
Selenium	1045	29	1%	0
Antimony	1074	29	1%	0
Beryllium	1075	29	1%	0
Thallium	1085	29	1%	0
Fluoride	1025	15	0%	0
Nitrate-Nitrite (Combined)	1038	1	0%	0

Disinfection Byproduct

Formed when chlorine reacts with organic matter in the water.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
TTHM (Total Trihalomethanes)	2950	94	2%	6
Total Haloacetic Acids (HAA5)	2456	92	2%	4

Treatment Technique

Rules that require a process, such as corrosion control or disinfection, rather than a measured limit.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
Lead and Copper Rule (LCR)	5000	144	4%	137
Groundwater Rule (GWR)	0700	141	4%	138
Lead and Copper Rule Revisions (LCRR)	5200	39	1%	39
Interim Enhanced Surface Water Treatment Rule	0300	4	0%	0
Long Term 2 Enhanced Surface Water Treatment Rule (LT2)	0800	1	0%	1

Monitoring and Reporting

Administrative requirements. No direct health risk from the violation itself.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
Consumer Confidence Rule (CCR)	7000	117	3%	117
Public Notification Rule	7500	79	2%	79

Volatile Organic Compound

Solvents and fuel components, usually monitored as a group, which is why the counts are similar.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
1,2,4-Trichlorobenzene	2378	66	2%	3
cis-1,2-Dichloroethylene	2380	66	2%	3
Xylenes, Total	2955	66	2%	3
Dichloromethane (Methylene Chloride)	2964	66	2%	3
o-Dichlorobenzene	2968	66	2%	3
p-Dichlorobenzene	2969	66	2%	3
Vinyl Chloride	2976	66	2%	3
1,1-Dichloroethylene	2977	66	2%	3
trans-1,2-Dichloroethylene	2979	66	2%	3
1,2-Dichloroethane	2980	66	2%	3
1,1,1-Trichloroethane	2981	66	2%	3
Carbon Tetrachloride	2982	66	2%	3
1,2-Dichloropropane	2983	66	2%	3
Trichloroethylene (TCE)	2984	66	2%	3
1,1,2-Trichloroethane	2985	66	2%	3
Tetrachloroethylene (PCE)	2987	66	2%	3
Chlorobenzene	2989	66	2%	3
Benzene	2990	66	2%	3
Toluene	2991	66	2%	3
Ethylbenzene	2992	66	2%	3
Styrene	2996	66	2%	3
Ethylene Dibromide (EDB)	2946	27	1%	2

Organic Chemical

Industrial and synthetic organic chemicals with a maximum contaminant level.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
Di(2-ethylhexyl) Adipate	2035	30	1%	2
Di(2-ethylhexyl) Phthalate	2039	30	1%	2
Hexachlorocyclopentadiene	2042	27	1%	2
Hexachlorobenzene	2274	27	1%	2
Benzo(a)pyrene	2306	27	1%	2
Pentachlorophenol	2326	27	1%	2
1,2-Dibromo-3-Chloropropane (DBCP)	2931	27	1%	2
2,3,7,8-TCDD (Dioxin)	2063	1	0%	0
Polychlorinated Biphenyls (PCBs)	2383	1	0%	0

Pesticide

Pesticides and herbicides, monitored as a group.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
Simazine	2037	32	1%	2
Atrazine	2050	32	1%	2
Alachlor (Lasso)	2051	32	1%	2
Glyphosate	2034	30	1%	2
2,4-D	2105	29	1%	2
Heptachlor Epoxide	2067	28	1%	2
Endrin	2005	27	1%	2
BHC-Gamma (Lindane)	2010	27	1%	2
Methoxychlor	2015	27	1%	2
Toxaphene	2020	27	1%	2
Dalapon	2031	27	1%	2
Diquat	2032	27	1%	2
Endothall	2033	27	1%	2
Oxamyl (Vydate)	2036	27	1%	2
Picloram	2040	27	1%	2
Dinoseb	2041	27	1%	2
Carbofuran	2046	27	1%	2
Heptachlor	2065	27	1%	2
2,4,5-TP (Silvex)	2110	27	1%	2
Chlordane	2959	27	1%	2

Radionuclide

Naturally occurring radioactive elements in groundwater.

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share
Gross Alpha, Excl. Radon and U	4000	48	1%
Radium-226	4020	48	1%
Radium-228	4030	48	1%

Other rules

Rule or contaminant	Code	Indiana systems with violations, 3 yr	Share	Unresolved
Carbon, Total	2920	4	0%	0

About this data

A system is counted once per rule if any of its violations in the past three years involved that rule, including monitoring and reporting lapses. Unresolved means still in violation at EPA's latest data refresh. Share is of the 3,935 active Indiana systems.

Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Indiana records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.