Know Your Environment. Protect Your Health.

CONTAMINANT

N-Nitrosodimethylamine (NDMA)

FOUND

Exceeding guidelines

STATES DETECTED

1

serves

3.7 million

utilities detected

18

states detected

1

serves

2,640

utilities detected

1

Overview

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. learn more about this contaminant

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.

State, National, and Health Guidelines for Drinking Water

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

National Standard Exists

Health Concerns:

  • Cancer

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N-Nitrosodimethylamine (NDMA) from your water?

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N-Nitrosodimethylamine (NDMA) around the Country

UTILITIES REPORTING ABOVE HEALTH GUIDELINES UTILITIES WITH CONTAMINATION
State Utilities People Served Utilities People Served
California12,640183,677,851

Utilities with the highest amounts of n-nitrosodimethylamine, 2021-2023

ALL UTILITIES
LARGE UTILITIES
Utility Location Tests Average level People served
Tesoro Viejo Master Mwc, Inc.San Jose, CA4 of 46.63 ppt2,640
City of PleasantonPleasanton, CA2 of 23.10 ppt79,871
Dublin San Ramon Services DistrictDublin, CA2 of 23.10 ppt98,776
Zone 7 Water Agency*Livermore, CA2 of 23.10 ppt40
City of LivermoreLivermore, CA2 of 23.10 ppt35,672
California Water Service - LivermoreSan Jose, CA2 of 23.10 ppt60,215
California Domestic Water Company*Whittier, CA27 of 1602.18 ppt290,814
Long Beach UtilitiesDepartmentLong Beach, CA1 of 12.10 ppt460,682
California Water Service Company - Palos VerdeSan Jose, CA14 of 202.01 ppt70,819
La Verne WDLa Verne, CA1 of 60.500 ppt32,206
Three Valleys Municipal Water District*Claremont, CA1 of 60.500 ppt67,018
Golden State Water Company (GSWC) - ClaremontSan Dimas, CA1 of 60.500 ppt39,279
California Water Service Company - East Los AngelesSan Jose, CA2 of 140.386 ppt151,902
Suburban Water Systems - San Jose HillsCovina, CA13 of 1840.164 ppt168,843
California Water Service (CWS) - Los Altos SuburbanSan Jose, CA1 of 500.0470 ppt70,175
City of CupertinoSan Jose, CA1 of 500.0470 ppt16,530
City of San Jose - EVG/EDV/COYSan Jose, CA1 of 500.0470 ppt98,198
Santa Clara Valley Water District*San Jose, CA1 of 500.0470 ppt1,934,171

* 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 N-Nitrosodimethylamine (NDMA), but it likely has the contaminant in its water supply.

UtilityLocationTestsAverage levelPeople served
California Water Service - LivermoreSan Jose, CA2 of 23.10 ppt60,215
City of PleasantonPleasanton, CA2 of 23.10 ppt79,871
Dublin San Ramon Services DistrictDublin, CA2 of 23.10 ppt98,776
City of LivermoreLivermore, CA2 of 23.10 ppt35,672
California Domestic Water Company*Whittier, CA27 of 1602.18 ppt290,814
Long Beach UtilitiesDepartmentLong Beach, CA1 of 12.10 ppt460,682
California Water Service Company - Palos VerdeSan Jose, CA14 of 202.01 ppt70,819
Golden State Water Company (GSWC) - ClaremontSan Dimas, CA1 of 60.500 ppt39,279
Three Valleys Municipal Water District*Claremont, CA1 of 60.500 ppt67,018
La Verne WDLa Verne, CA1 of 60.500 ppt32,206
California Water Service Company - East Los AngelesSan Jose, CA2 of 140.386 ppt151,902
Suburban Water Systems - San Jose HillsCovina, CA13 of 1840.164 ppt168,843
California Water Service (CWS) - Los Altos SuburbanSan Jose, CA1 of 500.0470 ppt70,175
City of CupertinoSan Jose, CA1 of 500.0470 ppt16,530
City of San Jose - EVG/EDV/COYSan Jose, CA1 of 500.0470 ppt98,198
Santa Clara Valley Water District*San Jose, CA1 of 500.0470 ppt1,934,171

* 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 N-Nitrosodimethylamine (NDMA), but it likely has the contaminant in its water supply.

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