Chlorate in Indiana Drinking Water
Ranked by max chlorate detected (µg/L) · UCMR 3 data (2013–2015) · Data from EPA SDWIS & UCMR
Chlorate in Indiana: what the data shows
Indiana has 32 cities with chlorate data from the EPA's UCMR 3 program (2013–2015). Chlorate exceeded the 210 µg/L EPA lifetime health advisory in 21 of those cities. The state average max detected level is 370.5 µg/L. Chlorate is a disinfection byproduct that forms when chlorine dioxide or hypochlorite solutions are used to disinfect drinking water. It is most common in systems that use chlorine dioxide for taste-and-odor control or that store hypochlorite for extended periods. There is no federal MCL — the EPA lifetime health advisory is 210 µg/L. Chlorate can interfere with thyroid function by blocking iodide uptake, an effect of particular concern for pregnant women, infants, and people with thyroid conditions. Reverse osmosis and ion exchange (anion-specific) are effective at removing chlorate; standard activated carbon filters provide only modest reduction.
Cities exceeding 210 µg/L EPA lifetime HA (no MCL)
Chlorate data across Indiana
Each dot is a city with UCMR 3 chlorate testing data. Cities where chlorate exceeds the 210 µg/L EPA lifetime health advisory are highlighted. Size reflects population served.
Top 10 cities by chlorate level in Indiana
Highest Chlorate levels (µg/L)
All Indiana cities ranked by chlorate level
| # | City | Level | Level | Over HA? | Violations | Grade |
|---|---|---|---|---|---|---|
| 1 | Indianapolis | 1800.0 µg/L | Over HA | 31 | C+ | |
| 2 | Greenwood | 880.0 µg/L | Over HA | 0 | A | |
| 3 | Brownsburg | 790.0 µg/L | Over HA | 0 | A- | |
| 4 | Lawrence | 640.0 µg/L | Over HA | 4 | B | |
| 5 | Ellettsville | 630.0 µg/L | Over HA | 6 | A- | |
| 6 | Plainfield | 580.0 µg/L | Over HA | 9 | B- | |
| 7 | Carmel | 560.0 µg/L | Over HA | 2 | B | |
| 8 | Kokomo | 510.0 µg/L | Over HA | 24 | F | |
| 9 | Noblesville | 510.0 µg/L | Over HA | 24 | D | |
| 10 | Morgantown | 410.0 µg/L | Over HA | 9 | C+ | |
| 11 | Newburgh | 401.0 µg/L | Over HA | 4 | A | |
| 12 | Huntingburg | 400.0 µg/L | Over HA | 14 | B- | |
| 13 | Valparaiso | 350.0 µg/L | Over HA | 3 | C- | |
| 14 | Mecca | 330.0 µg/L | Over HA | 6 | B+ | |
| 15 | East Chicago | 320.0 µg/L | Over HA | 1 | B- | |
| 16 | Bloomington | 310.0 µg/L | Over HA | 45 | D | |
| 17 | West Lafayette | 310.0 µg/L | Over HA | 2 | A- | |
| 18 | Mishawaka | 290.0 µg/L | Over HA | 8 | C+ | |
| 19 | South Bend | 250.0 µg/L | Over HA | 7 | F | |
| 20 | Lafayette | 250.0 µg/L | Over HA | 24 | F | |
| 21 | Corydon | 247.1 µg/L | Over HA | 0 | A | |
| 22 | Warsaw | 180.0 µg/L | No | 46 | F | |
| 23 | Fort Wayne | 170.0 µg/L | No | 17 | D | |
| 24 | New Haven | 160.0 µg/L | No | 1 | B+ | |
| 25 | Mooresville | 150.0 µg/L | No | 0 | B | |
| 26 | Michigan City | 110.0 µg/L | No | 12 | F | |
| 27 | Griffith | 95.0 µg/L | No | 2 | B | |
| 28 | Evansville | 88.0 µg/L | No | 9 | A- | |
| 29 | Lebanon | 52.6 µg/L | No | 7 | B+ | |
| 30 | Attica | 34.0 µg/L | No | 7 | A- | |
| 31 | Oakland City | 27.0 µg/L | No | 6 | B | |
| 32 | Anderson | 22.4 µg/L | No | 2 | B |
Frequently asked questions about chlorate in Indiana
Is chlorate in Indiana tap water dangerous?
Chlorate has no federal MCL. The EPA lifetime health advisory is 210 µg/L. 21 cities in Indiana exceed this level. Chlorate can interfere with thyroid iodide uptake, which is a particular concern for infants, pregnant women, and people with hypothyroidism.
Where does chlorate in Indiana water come from?
Chlorate is a byproduct of chlorine-based disinfectants — particularly chlorine dioxide and hypochlorite (bleach) solutions. Levels tend to be higher in systems that use chlorine dioxide for taste-and-odor treatment or store sodium hypochlorite at high concentrations or for long periods. Levels vary seasonally with disinfectant use.
How can I reduce chlorate exposure?
Reverse osmosis is the most effective home treatment for chlorate, typically removing 80–95%. Anion exchange systems also work but require regeneration. Standard activated carbon filters provide only limited chlorate reduction. Boiling does NOT remove chlorate.