Total trihalomethanes (TTHMs)

Erie County Water Authority (ECWA)

Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform. Read More.

Studies conducted in the U.S. and Europe have found that drinking tap water that carries disinfection byproducts increases the risk of developing bladder cancer. In animal studies, all trihalomethanes cause liver, kidney and intestinal tumors. Some human epidemiological studies also reported an association between disinfection byproducts and an increased risk of problems during pregnancy, including spontaneous miscarriage, cardiovascular defects, neural tube defects and low birth weight.

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

Click here to read more about disinfection byproducts.

MORE ABOUT THIS CONTAMINANT

290

Samples

Samples exceeding legal limit (MCL)

290

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2014	39.3 ppb	48	48	8.70 ppb - 75.0 ppb
2015	36.1 ppb	51	51	13.6 ppb - 66.0 ppb
2016	42.4 ppb	48	48	15.0 ppb - 79.4 ppb
2017	37.1 ppb	47	47	10.6 ppb - 64.9 ppb
2018	43.3 ppb	48	48	17.4 ppb - 85.1 ppb
2019	42.8 ppb	48	48	14.0 ppb - 78.3 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.15 ppb

EPA Maximum Contaminant
Level (MCL) 80 ppb

The legal limit for the group of four trihalomethanes, established in 1998, was based on the need for residual disinfectant levels in water served to customers and the cost of treatment. This limit does not fully protect against the risk of cancer due to exposure to trihalomethanes.

ppb = parts per billion

All test results

Date	Lab ID	Result
2014-02-16	20140216_523	52.2 ppb
2014-02-16	20140216_491	21.5 ppb
2014-02-16	20140216_340	18.2 ppb
2014-02-16	20140216_530	37.8 ppb
2014-02-16	20140216_484	37.6 ppb
2014-02-16	20140216_433	35.3 ppb
2014-02-18	20140218_1047	26.8 ppb
2014-02-18	20140218_402	21.3 ppb
2014-02-18	20140218_527	26.0 ppb
2014-02-18	20140218_393	34.1 ppb
2014-02-18	20140218_291	66.1 ppb
2014-02-18	20140218_391	25.8 ppb
2014-05-19	20140519	33.6 ppb
2014-05-19	20140519_393	33.1 ppb
2014-05-19	20140519_391	34.1 ppb
2014-05-19	20140519_291	34.8 ppb
2014-05-19	20140519_402	25.9 ppb
2014-05-19	20140519_491	24.7 ppb
2014-05-19	20140519_530	36.8 ppb
2014-05-19	20140519_1047	28.4 ppb
2014-05-19	20140519_527	25.9 ppb
2014-05-19	20140519_340	24.1 ppb
2014-05-19	20140519_523	51.9 ppb
2014-05-19	20140519_484	47.7 ppb
2014-08-18	1408F19-005	62.0 ppb
2014-08-18	1408F19-013	56.0 ppb
2014-08-18	1408F19-001	69.0 ppb
2014-08-18	1408F19-004	16.0 ppb
2014-08-18	1408F19-022	68.0 ppb
2014-08-18	1408F19-017	46.0 ppb
2014-08-18	1408F19-008	59.0 ppb
2014-08-18	1408F19-011	48.0 ppb
2014-08-18	1408F19-020	48.0 ppb
2014-08-18	1408F19-016	66.0 ppb
2014-08-18	1408F19-019	56.0 ppb
2014-08-18	1408F19-007	75.0 ppb
2014-11-17	1412027-019	30.0 ppb
2014-11-17	1412027-014	36.0 ppb
2014-11-17	1412027-012	50.0 ppb
2014-11-17	1412027-009	8.70 ppb
2014-11-17	1412027-013	49.0 ppb
2014-11-17	1412027-002	31.0 ppb
2014-11-17	1412027-010	41.0 ppb
2014-11-17	1412027-001	56.0 ppb
2014-11-17	1412027-005	20.0 ppb
2014-11-17	1412027-007	30.0 ppb
2014-11-17	1412027-017	25.0 ppb
2014-11-17	1412027-004	39.0 ppb
2015-02-17	523-20150217	56.9 ppb
2015-02-17	340-20150217	19.3 ppb
2015-02-17	391-20150217	26.4 ppb
2015-02-17	433-20150217	27.7 ppb
2015-02-17	1047-20150217	23.3 ppb
2015-02-17	291-20150217	18.6 ppb
2015-02-17	527-20150217	25.4 ppb
2015-02-17	393-20150217	27.8 ppb
2015-02-17	491-20150217	18.9 ppb
2015-02-17	402-20150217	18.9 ppb
2015-02-17	484-20150217	34.7 ppb
2015-02-18	530-20150218	28.7 ppb
2015-05-18	20150518-A	30.6 ppb
2015-05-18	340616W	35.0 ppb
2015-05-18	340616L	31.0 ppb
2015-05-18	340616A	45.0 ppb
2015-05-18	340616R	36.0 ppb
2015-05-18	340616B	35.0 ppb
2015-05-18	340616F	42.0 ppb
2015-05-18	34066BA	29.0 ppb
2015-05-18	340616	41.0 ppb
2015-05-18	340616ED	51.0 ppb
2015-05-18	340616N	38.0 ppb
2015-05-18	20150518	29.4 ppb
2015-05-18	340616TR	17.0 ppb
2015-05-18	20150518-B	44.9 ppb
2015-05-18	340616M	31.0 ppb
2015-08-20	347018-2	38.0 ppb
2015-08-20	347018-1	64.0 ppb
2015-08-21	347018-4	26.0 ppb
2015-08-21	347018-6	24.0 ppb
2015-08-21	347018-10	56.0 ppb
2015-08-21	347018-7	52.0 ppb
2015-08-21	347018-9	66.0 ppb
2015-08-21	347018-3	55.0 ppb
2015-08-21	347018-5	61.0 ppb
2015-08-21	347018-12	42.0 ppb
2015-08-21	347018-8	65.0 ppb
2015-08-21	347018-11	40.0 ppb
2015-11-16	11/16/2015-484	13.6 ppb
2015-11-16	11/16/2015-523	15.0 ppb
2015-11-16	11/16/2015-340	28.0 ppb
2015-11-16	11/16/2015-530	31.0 ppb
2015-11-16	11/16/2015-291	26.0 ppb
2015-11-16	11/16/2015-433	48.0 ppb
2015-11-16	11/16/2015-491	27.0 ppb
2015-11-16	11/16/2015-393	41.0 ppb
2015-11-16	11/16/2015-402	36.0 ppb
2015-11-16	11/16/2015-1047	41.0 ppb
2015-11-16	11/16/2015-391	51.0 ppb
2015-11-16	11/16/2015-527	33.0 ppb
2016-02-16	02/16/2016-527	20.1 ppb
2016-02-16	02/16/2016-393	27.3 ppb
2016-02-16	02/16/2016-402	18.4 ppb
2016-02-16	02/16/2016-291	18.0 ppb
2016-02-16	02/16/2016-1047	35.0 ppb
2016-02-16	02/16/2016-391	33.0 ppb
2016-02-16	02/16/2016-484	31.0 ppb
2016-02-17	02/17/2016-530	20.0 ppb
2016-02-17	02/17/2016-523	47.0 ppb
2016-02-18	02/18/2016-433	26.0 ppb
2016-02-18	02/18/2016-340	19.4 ppb
2016-02-18	02/18/2016-491	20.0 ppb
2016-05-16	05/16/2016-291	27.0 ppb
2016-05-16	05/16/2016-523	27.0 ppb
2016-05-16	05/16/2016-402	30.0 ppb
2016-05-16	05/16/2016-527	31.0 ppb
2016-05-16	05/16/2016-393	37.0 ppb
2016-05-16	05/16/2016-484	41.0 ppb
2016-05-16	05/16/2016-433	51.0 ppb
2016-05-16	05/16/2016-391	42.0 ppb
2016-05-16	05/16/2016-1047	28.0 ppb
2016-05-16	05/16/2016-340	27.0 ppb
2016-05-16	05/16/2016-491	27.0 ppb
2016-05-16	05/16/2016-530	35.0 ppb
2016-08-15	1608H81-013	26.8 ppb
2016-08-15	1608H81-001	79.4 ppb
2016-08-15	1608H81-007	58.2 ppb
2016-08-15	1608H81-002	75.6 ppb
2016-08-15	1608H81-008	67.5 ppb
2016-08-15	1608H81-009	60.8 ppb
2016-08-15	1608H81-010	77.1 ppb
2016-08-15	1608H81-015	69.1 ppb
2016-08-15	1608H81-003	68.0 ppb
2016-08-15	1608H81-014	31.5 ppb
2016-08-15	1608H81-005	60.3 ppb
2016-08-15	1608H81-012	66.0 ppb
2016-11-14	704956020	37.6 ppb
2016-11-14	704956013	51.8 ppb
2016-11-14	704956014	30.9 ppb
2016-11-14	704956011	54.4 ppb
2016-11-14	704956017	44.4 ppb
2016-11-14	704956010	57.6 ppb
2016-11-14	704956007	15.0 ppb
2016-11-14	704956001	61.0 ppb
2016-11-14	704656004	74.0 ppb
2016-11-14	704956008	36.3 ppb
2016-11-14	704956002	69.9 ppb
2016-11-14	705335001	46.0 ppb
2017-02-21	7011956014	42.9 ppb
2017-02-21	7011956016	23.7 ppb
2017-02-21	7011956012	26.4 ppb
2017-02-21	7011956001	37.3 ppb
2017-02-21	7011956002	24.3 ppb
2017-02-21	7011956009	26.8 ppb
2017-02-21	7011956021	25.0 ppb
2017-02-21	7011956007	64.9 ppb
2017-02-21	7011956004	49.4 ppb
2017-02-21	7011956015	35.8 ppb
2017-02-21	7011956019	25.5 ppb
2017-05-15	WOHLHUETER 5152	36.5 ppb
2017-05-15	AUTO INF 5152017	49.2 ppb
2017-05-15	FELLOW BAP 51520	55.2 ppb
2017-05-15	RICE HILL 515201	25.1 ppb
2017-05-15	TREVETT TANK 515	14.0 ppb
2017-05-15	TOPS MRKT 515201	23.3 ppb
2017-05-15	3330 BAKER 51520	24.7 ppb
2017-05-15	NAPA AUTO 515201	35.1 ppb
2017-05-15	MARILLA STAT 515	27.0 ppb
2017-05-16	BENNING TANK 516	58.2 ppb
2017-05-16	LACK FIRE 2 5162	28.7 ppb
2017-08-14	7027324003	56.6 ppb
2017-08-14	7027324004	62.7 ppb
2017-08-14	7027318002	46.0 ppb
2017-08-14	7027324001	44.8 ppb
2017-08-14	7027318001	23.2 ppb
2017-08-14	7027319004	51.1 ppb
2017-08-14	7027318007	53.9 ppb
2017-08-14	7027319002	32.7 ppb
2017-08-14	7027318004	47.3 ppb
2017-08-14	7027324005	48.6 ppb
2017-08-15	7027324009	37.3 ppb
2017-08-15	7027324008	32.5 ppb
2017-12-01	7037142003	48.9 ppb
2017-12-01	7037142011	26.8 ppb
2017-12-01	7037142013	24.5 ppb
2017-12-01	7037142002	22.0 ppb
2017-12-01	7037142004	45.8 ppb
2017-12-01	7037142016	50.9 ppb
2017-12-01	7037142017	48.5 ppb
2017-12-01	7037142007	46.3 ppb
2017-12-01	7037142009	28.1 ppb
2017-12-01	7037142001	10.6 ppb
2017-12-01	7037142018	39.6 ppb
2017-12-01	7037142020	23.5 ppb
2017-12-01	7037142014	32.9 ppb
2018-02-12	7042886008	18.9 ppb
2018-02-12	7042886001	32.2 ppb
2018-02-12	7042886021	49.0 ppb
2018-02-12	7042886010	20.9 ppb
2018-02-12	7042886017	35.3 ppb
2018-02-12	7042886004	34.8 ppb
2018-02-12	7042886012	17.4 ppb
2018-02-12	7042886003	34.3 ppb
2018-02-12	7042886014	42.7 ppb
2018-02-12	7042886019	21.3 ppb
2018-02-12	7042886011	63.3 ppb
2018-02-12	7042886005	32.8 ppb
2018-05-14	ECWA7 DBP 2ND Q	34.6 ppb
2018-05-14	ECWA 3 DBP 2ND Q	29.0 ppb
2018-05-14	ECWA 5 DBP 2ND Q	32.3 ppb
2018-05-14	ECWA 2 DBP 2ND Q	30.0 ppb
2018-05-14	ECWA 4 DBP 2ND Q	42.8 ppb
2018-05-14	ECWA12 DBP 2ND Q	30.7 ppb
2018-05-14	ECWA10 DBP 2ND Q	33.0 ppb
2018-05-14	ECWA 1 DBP 2ND Q	38.0 ppb
2018-05-14	ECWA9 DBP 2ND Q	27.4 ppb
2018-05-14	ECWA 6 DBP 2ND Q	38.0 ppb
2018-05-15	ECWA11 DBP 2ND Q	29.2 ppb
2018-05-16	ECWA8 DBP 2ND Q	37.3 ppb
2018-08-13	DBP2 ECWA 3RDQ 1	37.9 ppb
2018-08-13	DBP2 ECWA 3RDQ18	67.0 ppb
2018-08-13	DBP 2 ECWA 3RDQ	63.2 ppb
2018-08-13	DBP2 ECWA 3RDQ 1	82.9 ppb
2018-08-13	DBP 2 ECWA 3RDQ	82.0 ppb
2018-08-13	DBP2 ECWA 3RD Q1	30.0 ppb
2018-08-13	DBP2 ECWA 3RD Q	76.8 ppb
2018-08-13	DBP2 ECWA 3RDQ 1	79.0 ppb
2018-08-13	DBP 2 ECWA 3RD Q	52.3 ppb
2018-08-13	DBP 2 ECWA 3RDQ1	69.7 ppb
2018-08-13	DBP2 ECWA 3RD Q1	85.1 ppb
2018-08-13	DBP2 ECWA 3RDQ 1	57.2 ppb
2018-12-04	ECWA 4TH Q 18 12	51.5 ppb
2018-12-04	ECWA DBP2 4THQ 1	45.3 ppb
2018-12-04	ECWA DBP2 4THQ 1	51.5 ppb
2018-12-04	ECWA DBP 4THQ 18	40.0 ppb
2018-12-04	ECWA DBP 4TH Q 1	51.5 ppb
2018-12-04	ECWA DBP2 4THQ18	34.0 ppb
2018-12-04	ECWA DBP 4TH Q 1	33.0 ppb
2018-12-04	ECWA DBP 4THQ 18	20.9 ppb
2018-12-04	DBP2 ECWA 4THQ 1	33.3 ppb
2018-12-04	ECWA DBP 4THQ 18	48.0 ppb
2018-12-04	ECWA DBP 4THQ 18	39.0 ppb
2018-12-04	ECWA DBP 4THQ 18	42.0 ppb
2019-02-19	484 DBP 1ST Q 19	41.0 ppb
2019-02-19	527 DBP 1ST Q 19	24.0 ppb
2019-02-19	433 DBP 1ST Q 19	43.0 ppb
2019-02-19	491 DBP 1ST Q 19	29.0 ppb
2019-02-19	SITE 340 1ST Q 2	27.0 ppb
2019-02-19	SITE 391 DBP 1ST	30.2 ppb
2019-02-19	SITE 393 DBP 1ST	33.0 ppb
2019-02-19	523 DBP 1ST Q 19	49.0 ppb
2019-02-19	SITE 402 DBP 1ST	30.4 ppb
2019-02-19	1047 DBP 1ST Q 1	30.9 ppb
2019-02-19	530 DBP 1ST Q 19	34.6 ppb
2019-02-19	DBP 1ST Q 291	25.8 ppb
2019-05-21	393 DBP 2ND Q 19	37.5 ppb
2019-05-21	1047 DBP 2ND Q 1	37.4 ppb
2019-05-21	523 DBP 2ND Q 19	29.3 ppb
2019-05-21	291 DBP 2ND Q 19	25.5 ppb
2019-05-21	391 DBP 2ND Q 19	41.8 ppb
2019-05-21	484 DBP 2ND Q 19	36.9 ppb
2019-05-21	530 DBP 2ND Q 19	40.8 ppb
2019-05-21	527 DBP 2ND Q 19	32.1 ppb
2019-06-20	340 DBP 2ND Q 19	27.2 ppb
2019-06-20	491 DBP 2ND Q 19	32.6 ppb
2019-06-20	433 DBP 2ND Q 19	43.0 ppb
2019-06-20	402 DBP 2ND Q 19	32.2 ppb
2019-08-27	402 3RD Q 19 DBP	66.1 ppb
2019-08-27	484 3RD Q 19 DBP	38.8 ppb
2019-08-27	393 3RD Q 19 DBP	78.3 ppb
2019-08-27	340 3RD Q 19 DBP	50.5 ppb
2019-08-27	5223 3RD Q 19 DB	55.7 ppb
2019-08-27	530 3RD Q 19 DBP	74.8 ppb
2019-08-27	527 3RD Q 19 DBP	66.2 ppb
2019-08-27	1047 3RD Q 19 DB	69.8 ppb
2019-08-27	433 3RD Q 19 DBP	69.4 ppb
2019-08-27	391 3RD Q 19	77.8 ppb
2019-08-27	491 3RD Q 19 DBP	55.5 ppb
2019-08-27	291 3RD Q 19 DBP	71.8 ppb
2019-11-19	393 DBP 4TH Q	44.7 ppb
2019-11-19	402 4TH Q 2019 D	32.0 ppb
2019-11-19	527 4TH Q 19 DBP	43.7 ppb
2019-11-19	340 4TH Q DBP	31.4 ppb
2019-11-19	433 4TH Q 2019 D	45.5 ppb
2019-11-19	484 4TH Q 19 DBP	25.4 ppb
2019-11-19	530 4TH Q 19 DBP	55.0 ppb
2019-11-19	1047 4TH Q 19 DB	51.0 ppb
2019-11-19	391 DBP 4TH Q	47.5 ppb
2019-11-19	291 DBP 4TH Q	35.9 ppb
2019-11-19	523 4TH Q 19 DBP	14.0 ppb
2019-11-19	491 4TH Q 19 DBP	39.4 ppb