Menu

EWG's Tap Water Database — 2021 UPDATE

Donate

N-Nitrosodimethylamine (NDMA)

Suburban Water Systems - San Jose Hills

N-Nitrosodimethylamine is one of the DNA-damaging, cancer-causing contaminants called N-nitrosamines that can form during water treatment with the use of certain disinfectants, such as chloramine. Read More.

Pollution of water sources with effluent from municipal wastewater treatment plants and runoff from animal feeding operations contributes to nitrosamine formation. Fifteen different nitrosamines are listed as carcinogens in the U.S. Department of Health and Human Services National Toxicology Program Report on Carcinogens. The federal government has not set a legal limit for nitrosamines in drinking water and water utilities typically do not test for these contaminants. California has set a public health goal for one of the most common nitrosamines, N-nitrosodimethylamine or NDMA, at 0.003 parts per billion in drinking water, a concentration that corresponds to an estimated one-in-one-million cancer risk.

Click here to read more about disinfection byproducts.

 

175

Samples

0

Samples exceeding legal limit (MCL)

12

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
2014ND350ND
20150.111 ppt181ND - 2.00 ppt
20160.0660 ppt321ND - 2.10 ppt
20170.891 ppt3512ND - 3.70 ppt
20181.00 ppt3512ND - 3.60 ppt
20191.25 ppt207ND - 4.20 ppt

ppt = parts per trillion

State and national drinking water standards and health guidelines

EWG Health Guideline 3 ppt

The EWG Health Guideline of 3 ppt for n-nitrosodimethylamine was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

ppt = parts per trillion

All test results

Date Lab ID Result
2014-01-139588-065-1036ND
2014-01-139588-075-1045ND
2014-02-119588-065-1041ND
2014-02-119588-075-1101ND
2014-02-219588-071-1322ND
2014-03-119588-071-1349ND
2014-03-129588-065-1323ND
2014-03-129588-075-1337ND
2014-04-159588-065-1125ND
2014-04-159588-071-1101ND
2014-04-159588-075-1350ND
2014-05-139588-065-1015ND
2014-05-139588-071-0937ND
2014-05-139588-075-1031ND
2014-06-099588-065-1006ND
2014-06-099588-071-0934ND
2014-06-099588-075-1026ND
2014-07-109588-065-1000ND
2014-07-109588-075-1015ND
2014-07-159588-071-1227ND
2014-08-119588-065-0928ND
2014-08-119588-071-0846ND
2014-08-119588-075-0944ND
2014-09-109588-071-1245ND
2014-09-179588-065-0957ND
2014-09-179588-075-1017ND
2014-10-159588-065-0953ND
2014-10-159588-075-1004ND
2014-10-179588-071-1030ND
2014-11-219588-065-1021ND
2014-11-219588-071-0950ND
2014-11-219588-075-1032ND
2014-12-159588-065-1012ND
2014-12-159588-071-0940ND
2014-12-159588-075-1030ND
2015-01-199588-071-1125ND
2015-02-209588-071-1038ND
2015-03-109588-071-1030ND
2015-04-159588-071-1338ND
2015-05-019588-075-1043ND
2015-05-119588-071-0925ND
2015-06-159588-071-1055ND
2015-06-209588-075-22162.00 ppt
2015-07-159588-065-1351ND
2015-07-159588-071-1338ND
2015-07-159588-075-1405ND
2015-08-129588-065-0942ND
2015-08-129588-071-0920ND
2015-08-129588-075-0953ND
2015-09-109588-065-1132ND
2015-09-109588-075-1153ND
2015-09-119588-071-0925ND
2015-10-129588-071-1010ND
2016-01-129588-071-0942ND
2016-02-089588-075-1045ND
2016-02-179588-065-1216ND
2016-02-179588-071-1145ND
2016-03-019588-065-1100ND
2016-03-019588-071-1038ND
2016-03-019588-075-1120ND
2016-04-069588-065-1341ND
2016-04-069588-071-1320ND
2016-04-069588-075-1403ND
2016-05-029588-065-1058ND
2016-05-029588-071-1001ND
2016-05-029588-075-1108ND
2016-06-279588-065-1040ND
2016-06-279588-071-0950ND
2016-06-279588-075-1057ND
2016-07-199588-065-0940ND
2016-07-199588-075-1218ND
2016-08-169588-065-1430ND
2016-08-169588-071-1520ND
2016-08-169588-075-1545ND
2016-09-199588-065-1140ND
2016-09-199588-075-1240ND
2016-10-109588-071-1628ND
2016-10-119588-065-0854ND
2016-10-119588-075-0908ND
2016-11-049588-065-1150ND
2016-11-049588-071-1135ND
2016-11-049588-075-1248ND
2016-12-139588-065-1135ND
2016-12-139588-071-1055ND
2016-12-149588-075-07102.10 ppt
2017-01-039588-065-1044ND
2017-01-039588-075-11052.60 ppt
2017-02-089588-070-0840ND
2017-02-209588-065-1125ND
2017-02-209588-075-11362.20 ppt
2017-03-079588-071-0943ND
2017-03-079588-075-10202.20 ppt
2017-03-089588-065-0945ND
2017-04-119588-065-1013ND
2017-04-119588-071-1002ND
2017-04-119588-075-10322.10 ppt
2017-05-039588-065-1125ND
2017-05-039588-071-1102ND
2017-05-039588-075-11502.50 ppt
2017-06-099588-065-0851ND
2017-06-099588-071-0842ND
2017-06-099588-075-09112.40 ppt
2017-07-119588-065-1112ND
2017-07-119588-071-1033ND
2017-07-119588-075-11352.50 ppt
2017-08-119588-065-0932ND
2017-08-119588-071-0903ND
2017-08-119588-075-09433.00 ppt
2017-09-119588-065-1150ND
2017-09-119588-071-1034ND
2017-09-119588-075-12053.70 ppt
2017-10-179588-065-0956ND
2017-10-179588-071-0852ND
2017-10-179588-075-10302.50 ppt
2017-11-179588-065-0845ND
2017-11-179588-071-0822ND
2017-11-179588-075-09102.70 ppt
2017-12-159588-065-1334ND
2017-12-159588-071-1325ND
2017-12-159588-075-13422.80 ppt
2018-01-179588-065-0901ND
2018-01-179588-071-0841ND
2018-01-179588-075-09122.40 ppt
2018-02-069588-065-1030ND
2018-02-069588-071-1018ND
2018-02-069588-075-10422.80 ppt
2018-03-079588-065-0858ND
2018-03-079588-075-09102.20 ppt
2018-03-129588-071-0915ND
2018-04-119588-065-0933ND
2018-04-119588-075-09552.50 ppt
2018-05-039588-065-1110ND
2018-05-039588-071-1035ND
2018-05-039588-075-11213.10 ppt
2018-06-019588-071-1020ND
2018-06-049588-065-0848ND
2018-06-049588-075-09003.30 ppt
2018-07-069588-065-0912ND
2018-07-069588-071-0906ND
2018-07-069588-075-09382.60 ppt
2018-08-069588-065-0856ND
2018-08-069588-075-09143.60 ppt
2018-08-079588-071-0913ND
2018-09-219588-065-0842ND
2018-09-219588-075-09033.00 ppt
2018-09-269588-071-1018ND
2018-10-029588-065-0908ND
2018-10-029588-075-09583.60 ppt
2018-10-039588-071-0855ND
2018-11-069588-065-0935ND
2018-11-069588-071-0858ND
2018-11-069588-075-12383.10 ppt
2018-12-049588-071-0843ND
2018-12-049588-075-09082.90 ppt
2018-12-129588-065-1345ND
2019-01-119588-065-1020ND
2019-01-119588-075-10454.20 ppt
2019-02-089588-065-0805ND
2019-02-089588-075-09203.80 ppt
2019-03-049588-065-1330ND
2019-03-119588-075-12152.80 ppt
2019-04-089588-065-1028ND
2019-04-089588-075-10453.40 ppt
2019-05-079588-065-0853ND
2019-05-079588-075-09053.40 ppt
2019-06-109588-075-10353.30 ppt
2019-07-109588-065-1011ND
2019-07-109588-075-10254.10 ppt
2019-08-089588-065-1249ND
2019-09-129588-065-0941ND
2019-10-099588-065-1215ND
2019-10-099588-071-1200ND
2019-11-209588-065-1045ND
2019-12-129588-065-1010ND
2019-12-129588-071-1031ND