Chloroform

Status: No national drinking water standard exists

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Read More.

In addition to tap water disinfection, chloroform pollution in the environment also comes from industrial discharges from pulp and paper mills, and from urban wastewater effluent. Human studies show that chloroform damages the kidneys, liver and central nervous system. In animals, chloroform causes infertility, birth defects and cancer.

Click here to read more about disinfection byproducts.

2017-2019:

FOUND

FOUND ABOVE HEALTH GUIDELINES

states detected

25,077

utilities detected

237 million

people served

states over health guideline

22,985

utilities over health guideline

226 million

people served over health guideline

Health concerns for chloroform

Cancer

Harm to fetal growth and development

State and national drinking water standards and health guidelines

EWG Health Guideline 0.4 ppb

The EWG Health Guideline of 0.4 ppb for chloroform was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

ppb = parts per billion

States reporting chloroform in drinking water

	UTILITIES REPORTING ABOVE HEALTH GUIDELINES			UTILITIES WITH CONTAMINATION
State	Utilities	People Served		Utilities	People Served
California		998	29,315,638			1,155	32,799,147
Texas		2,362	24,832,072			2,709	25,783,638
New York		1,302	18,882,462			1,373	19,994,543
Illinois		1,500	11,993,570			1,518	12,029,298
Pennsylvania		1,307	11,060,535			1,354	11,148,005
Ohio		970	9,883,626			1,046	9,985,758
Georgia		736	8,882,381			911	9,119,485
North Carolina		871	8,772,955			888	8,810,100
New Jersey		440	8,415,225			499	8,787,919
Virginia		670	6,633,607			718	6,667,024
Massachusetts		305	6,322,027			335	6,502,901
Colorado		576	6,002,752			602	6,050,657
Washington		737	5,206,836			864	5,884,234
Tennessee		321	5,643,227			323	5,777,240
Alabama		276	4,586,360			327	5,063,536
Louisiana		840	4,757,184			922	4,921,865
Missouri		711	4,610,142			826	4,869,558
Minnesota		604	3,921,043			656	4,236,221
South Carolina		354	3,831,999			364	3,957,742
Wisconsin		507	3,628,155			570	3,920,109
Michigan		490	3,496,198			531	3,583,585
Oklahoma		614	3,346,431			656	3,439,166
Utah		193	2,704,298			229	2,817,294
Maryland		213	2,749,310			216	2,765,114
Nevada		47	2,609,811			69	2,708,882
Arkansas		550	2,618,564			584	2,706,155
Connecticut		216	2,640,181			237	2,664,405
Iowa		756	2,472,061			794	2,640,540
Kansas		662	2,262,249			715	2,376,180
Indiana		129	2,060,178			131	2,156,630
Mississippi		482	1,865,427			486	1,874,401
New Mexico		145	1,254,563			210	1,644,662
West Virginia		389	1,534,268			397	1,542,185
Nebraska		104	1,201,662			126	1,243,096
Delaware		126	948,814			136	998,233
New Hampshire		200	750,196			239	775,507
North Dakota		280	681,096			284	684,965
Rhode Island		38	625,101			41	626,130
Alaska		170	598,280			173	610,184
Montana		214	467,843			235	569,491
Arizona		52	346,678			59	507,303
Hawaii		30	216,183			37	477,146
Vermont		215	441,695			245	467,580
Wyoming		154	332,280			158	333,057
Maine		99	316,268			102	325,811
Idaho		17	249,863			18	251,163
Kentucky		9	203,281			7	107,630
South Dakota		4	2,306			2	746

LESS

Filtering technologies that reduce chloroform

Utilities with the highest amounts of chloroform, 2017-2019

ALL UTILITIES

LARGE UTILITIES

Utility	Location	Tests	Average level	People served
Asher Utility Dev Authority	Asher, OK	21 of 21	214.4 ppb	375
Hudson Gaars Mill Water System	Dodson, LA	74 of 74	210.0 ppb	660
Vixen Water System West	Chatham, LA	92 of 92	191.9 ppb	288
Thorne Bay, City of	Thorne Bay, AK	21 of 22	185.0 ppb	470
Wanette Public Works Authority	Wanette, OK	23 of 23	171.4 ppb	402
Boswell Public Works Authority	Boswell, OK	38 of 38	167.3 ppb	932
Vixen Water System East	Chatham, LA	72 of 72	162.3 ppb	486
Osage County Rural Water District # 20 (hulah)	Bartlesville, OK	22 of 22	155.6 ppb	350
Fairview Union Water System*	Coushatta, LA	98 of 98	154.8 ppb	2,205
Sandy Point 480 Water System	Campti, LA	80 of 84	150.4 ppb	675
Grayhorse Rural Water District	Fairfax, OK	22 of 22	146.2 ppb	100
Lakewood Water System	Lufkin, TX	27 of 27	138.8 ppb	42
Pittsburg	Pittsburg, OK	23 of 23	136.2 ppb	280
Beechwood Water Supply Corporation	Hemphill, TX	38 of 38	134.1 ppb	1,372
City of Nome	Nome, TX	50 of 50	133.2 ppb	602
Osage County Rural Water District # 5	Barnsdall, OK	45 of 45	129.7 ppb	561
Orient Water Company	Tonasket, WA	25 of 26	127.6 ppb	85
Stringtown Public Works Authority*	Stringtown, OK	43 of 43	125.8 ppb	1,105
Severy, City of	Severy, KS	22 of 22	124.0 ppb	230
Csp - Big Basin State Park	Felton, CA	49 of 49	117.8 ppb	3,029
Latimer County Rural Water District #3	Wister, OK	9 of 9	113.0 ppb	175
Lowndes County-spring Creek S/d	Valdosta, GA	54 of 54	112.7 ppb	2,959
Cloverhill 3 - Consecutive To Md0100015	Frederick, MD	2 of 2	111.8 ppb	888
Red Gate Mobile Home Park	Port Orchard, WA	9 of 9	111.0 ppb	23
Galena Water System Wtp-1	Galena, AK	24 of 24	109.9 ppb	670
Elk City, City of	Elk City, KS	23 of 23	109.3 ppb	294
Winebrook Hills Water District	Newcomb, NY	21 of 21	108.0 ppb	250
Barnsdall*	Barnsdall, OK	44 of 44	107.8 ppb	1,243
City of Strawn	Strawn, TX	30 of 30	107.7 ppb	696
Tower View	Northwood, NH	1 of 3	106.7 ppb	55
Cleveland Municipal Authority	Cleveland, OK	63 of 63	106.6 ppb	3,262
Alberta Water System	Castor, LA	92 of 96	106.0 ppb	1,860
Canyon Crest Mutual Benefit Water Company	Arroyo Grande, CA	3 of 3	105.3 ppb	125
Camak	Camak, GA	16 of 16	105.3 ppb	131
Md#01 Hidden Lake Estates	Madera, CA	21 of 21	105.0 ppb	162
Leflore County Rural Water District #3	Whitesboro, OK	59 of 59	104.6 ppb	1,643
Central Oklahoma Juvenile Center	Tecumseh, OK	22 of 22	104.5 ppb	265
Seminole County Rural Water District #1	Wewoka, OK	22 of 22	104.4 ppb	387
Ryan Utilities Authority	Ryan, OK	47 of 47	102.7 ppb	800
Weleetka Public Works Authority	Weleetka, OK	49 of 49	102.1 ppb	998
Okmulgee County Rural Water District #1	Schulter, OK	47 of 47	101.9 ppb	1,890
Sa#16 Sumner Hill-water System	Madera, CA	26 of 26	101.8 ppb	128
Okmulgee County Rural Water District #6 (hectorville)	Mounds, OK	55 of 55	100.6 ppb	8,370
Avant Utilities Authority	Avant, OK	27 of 27	100.1 ppb	361
Anthony Harbor Subdivision	Lufkin, TX	27 of 27	98.7 ppb	109
Choctaw County Rural Water System & Solid Waste Management District #6*	Boswell, OK	36 of 41	98.5 ppb	850
Mccurtain Municipal Authority	Mccurtain, OK	48 of 48	96.4 ppb	560
Maysville	Maysville, OK	51 of 51	96.0 ppb	1,212
Talihina PWA*	Talihina, OK	48 of 48	93.9 ppb	1,297
Pushmataha County Rural Water District #3	Antlers, OK	47 of 47	93.1 ppb	4,825

* This water utility supplies finished drinking water to at least one other water utility. The purchasing utility is not required to test for or report Chloroform, but it likely has the contaminant in its water supply.

Utility	Location	Tests	Average level	People served
Longmeadow Water Department	Longmeadow, MA	16 of 16	76.4 ppb	15,701
Bloomfield Water Department	Bloomfield, NJ	96 of 96	63.0 ppb	47,315
East Longmeadow DPW Water Department	East Longmeadow, MA	80 of 80	62.5 ppb	16,162
Claremore*	Claremore, OK	87 of 87	62.2 ppb	15,873
Okmulgee*	Okmulgee, OK	101 of 101	61.8 ppb	13,495
Belleville Water Department*	Belleville, NJ	96 of 96	60.1 ppb	35,129
Naval Station Washington - WNY	Washington Navy Yard, DC	1 of 1	58.0 ppb	15,690
Lincoln Water Commission	Lincoln, RI	76 of 80	57.6 ppb	21,137
Quantico Marine Base-Mainside*	Quantico, VA	101 of 101	57.3 ppb	14,525
Washington Water Authority WWA	Farmington, AR	92 of 92	57.0 ppb	16,750
James Fork Regional Water District*	Greenwood, AR	101 of 101	56.6 ppb	11,538
Albemarle County Service Authority (ACSA) Urban Area	Charlottesville, VA	4 of 4	56.5 ppb	66,983
East Providence	East Providence, RI	57 of 57	56.2 ppb	48,688
Floyd Water District*	Rome, NY	23 of 24	55.6 ppb	34,560
Warren City PWS*	Cortland, OH	96 of 96	55.6 ppb	46,832
Buchanan County PSA*	Vansant, VA	96 of 96	55.4 ppb	19,326
Lincoln Park Water Department*	Lincoln Park, NJ	96 of 96	55.4 ppb	11,000
Newark Water Department*	Newark, NJ	304 of 305	54.7 ppb	294,274
City of Troy Public Utilities*	Troy, NY	22 of 22	54.1 ppb	117,581
Watertown City*	Watertown, NY	275 of 277	53.9 ppb	29,406
Bridgeport City Of	Bridgeport, WV	48 of 48	53.8 ppb	10,309
Barrow County Water System*	Winder, GA	48 of 48	53.7 ppb	14,043
Mohawk Correctional Facility*	Rome, NY	24 of 24	53.5 ppb	34,775
Harrisburg*	Harrisburg, NC	96 of 96	53.2 ppb	17,127
Eatonton Putnam Water & Sewer Authority	Eatonton, GA	48 of 48	52.9 ppb	12,561
Oneonta City	Oneonta, NY	35 of 35	52.8 ppb	15,779
Guilderland Town WD	Guilderland, NY	98 of 98	52.7 ppb	30,000
McAlester PWA*	Mcalester, OK	107 of 107	52.6 ppb	18,206
Valdosta*	Valdosta, GA	98 of 98	52.5 ppb	51,769
Wvaw - Weston*	Weston, WV	98 of 98	52.2 ppb	11,797
Tri County Joint Municipal Authority*	Fredericktown, PA	93 of 94	51.9 ppb	10,100
E Stroudsburg Boro Water Dept*	East Stroudsburg, PA	87 of 88	51.5 ppb	13,000
College Utilities Corporation*	Fairbanks, AK	96 of 96	50.8 ppb	27,000
City of Conover*	Conover, NC	96 of 96	50.8 ppb	14,732
Newark Village*	Shortsville, NY	48 of 48	50.8 ppb	20,762
East Greenbush General WD	East Greenbush, NY	94 of 94	50.7 ppb	10,200
Bryant Waterworks*	Bryant, AR	92 of 92	50.6 ppb	19,607
Bristol County Water Authority*	Warren, RI	108 of 131	50.5 ppb	51,000
Exeter Water Department	Exeter, NH	80 of 81	50.2 ppb	11,000
US Air Force Academy	Usaf Academy, CO	56 of 56	50.0 ppb	16,876
City Corporation*	Russellville, AR	95 of 95	49.9 ppb	29,260
El Dorado ID - Main*	Placerville, CA	244 of 250	49.5 ppb	112,000
Assumption Parish Waterworks District 1*	Napoleonville, LA	200 of 202	49.5 ppb	22,862
Hannibal	Hannibal, MO	102 of 102	49.3 ppb	17,916
Girard City PWS	Girard, OH	92 of 92	49.2 ppb	15,000
Duncan Public Utilities Authority*	Duncan, OK	97 of 98	49.0 ppb	23,000
Somerset Water Department	Somerset, MA	85 of 85	48.9 ppb	18,257
City of Paris*	Paris, TX	102 of 102	48.9 ppb	25,498
Bella Vista POA	Bella Vista, AR	92 of 92	48.7 ppb	27,228
South Central Water Assn	Raymond, MS	93 of 93	48.6 ppb	11,930