EWG's Tap Water Database — 2021 UPDATE



Status: National drinking water standard exists


Simazine is a hormone-disrupting herbicide related to atrazine. It affects the male and female reproductive systems. In studies of laboratory animals, simazine increases blood levels of estrogen, decreases prolactin and progesterone, and causes mammary and ovarian tumors.




states detected


utilities detected

19 million

people served


states over health guideline


utilities over health guideline

2.7 million

people served over health guideline

Health concerns for simazine

Harm to the developing fetus

Hormone disruption

Harm to the reproductive system

Changes in the nervous system

Changes in brain and behavior


State and national drinking water standards and health guidelines

EWG Health Guideline 0.1 ppb

The EWG Health Guideline of 0.1 ppb for simazine was defined by EWG based on epidemiological studies of human exposure to atrazine in drinking water. This health guideline protects against harm to the developing fetus, harm to the reproductive system and hormone disruption.

EPA Maximum Contaminant
Level (MCL) 4 ppb

The legal limit for simazine, established in 1992, was based on toxicity studies in laboratory animals conducted in the 1980s. This limit does not fully protect against harm to the reproductive system, harm to the developing fetus, and hormone disruption.

ppb = parts per billion

States reporting simazine in drinking water

State UtilitiesPeople Served UtilitiesPeople Served
North Carolina1475,744561,127,156
Rhode Island00467,053
West Virginia0016,797

Filtering technologies that reduce simazine

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Activated Carbon

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Reverse Osmosis

Utilities with the highest amounts of simazine, 2017-2019

UtilityLocationTestsAverage levelPeople served
Mount OliveMount Olive, IL11 of 240.552 ppb2,150
Salem*Salem, IL7 of 230.452 ppb9,000
Hillsboro*Hillsboro, IL11 of 250.427 ppb4,359
Schram CityHillsboro, IL11 of 250.427 ppb586
Taylor SpringsTaylor Springs, IL11 of 250.427 ppb600
CoffeenAviston, IL11 of 250.427 ppb685
GreenfieldGreenfield, IL3 of 200.380 ppb1,200
Carlinville*Carlinville, IL8 of 250.374 ppb5,917
Lake Williamson Christian CenterCarlinville, IL8 of 250.374 ppb1,250
Westwego WaterworksWestwego, LA2 of 40.355 ppb8,534
EvansvilleEvansville, IL6 of 230.341 ppb700
VernonVernon, IL8 of 240.325 ppb129
XeniaXenia, IL8 of 240.325 ppb545
FarinaFarina, IL8 of 240.325 ppb600
Fmc Water Company*Odin, IL8 of 240.325 ppb3,129
PatokaPatoka, IL8 of 240.325 ppb603
Gateway Regional Water Company*Sandoval, IL8 of 240.325 ppb1
Flora*Flora, IL8 of 240.325 ppb5,478
Sparta*Sparta, IL9 of 240.292 ppb4,600
CoultervilleCoulterville, IL2 of 140.276 ppb985
Jericho Water DistrictSyosset, NY30 of 970.260 ppb58,000
SummerfieldSummerfield, IL8 of 260.247 ppb471
S L M Water Commission*Mascoutah, IL8 of 260.247 ppb300
Fsh Water Commission*Freeburg, IL8 of 260.247 ppb310
FayettevilleSwansea, IL8 of 260.247 ppb441
New Baden*New Baden, IL8 of 260.247 ppb3,349
LebanonLebanon, IL8 of 260.247 ppb4,418
New Memphis Public Water DistrictNew Memphis, IL8 of 260.247 ppb900
TrentonTrenton, IL8 of 260.247 ppb3,180
MascoutahMascoutah, IL8 of 260.247 ppb9,002
Tritownship Water District*Trenton, IL8 of 260.247 ppb4,025
City of GrapevineGrapevine, TX7 of 90.239 ppb47,851
W G Murray Development CenterCenralia, IL8 of 240.235 ppb290
Centralia*Centralia, IL8 of 240.235 ppb14,274
WamacCentralia, IL8 of 240.235 ppb1,501
Junction CityCentralia, IL8 of 240.235 ppb514
Irvington*Centralia, IL8 of 240.235 ppb1,245
Walnut Hill*Centralia, IL8 of 240.235 ppb1,305
SandovalSandoval, IL8 of 240.235 ppb1,528
Hoyleton RwcCentralia, IL8 of 240.235 ppb1,147
KinmundyKinmundy, IL2 of 80.235 ppb940
Apple Creek Water Co-opWaverly, IL3 of 140.229 ppb949
Waverly*Waverly, IL3 of 140.229 ppb1,307
Fort Bend County MUD 134eHouston, TX5 of 320.218 ppb219
Fort Bend County Municipal Utility District 134dHouston, TX5 of 320.218 ppb105
Pecan Grove MUD*Houston, TX5 of 320.218 ppb14,913
HumboldtHumboldt, IL6 of 240.201 ppb437
Mattoon*Mattoon, IL6 of 240.201 ppb19,000
Osceola Water Works*Osceola, IA2 of 40.200 ppb4,929
Sirwa #3 (osceola)Creston, IA2 of 40.200 ppb2,573

* 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 Simazine, but it likely has the contaminant in its water supply.

UtilityLocationTestsAverage levelPeople served
Jericho Water DistrictSyosset, NY30 of 970.260 ppb58,000
City of GrapevineGrapevine, TX7 of 90.239 ppb47,851
Centralia*Centralia, IL8 of 240.235 ppb14,274
Pecan Grove MUD*Houston, TX5 of 320.218 ppb14,913
Mattoon*Mattoon, IL6 of 240.201 ppb19,000
Town of Smithfield*Smithfield, NC7 of 190.186 ppb12,400
E J Water Corp*Dieterich, IL5 of 200.156 ppb23,669
Town of Tarboro*Tarboro, NC5 of 180.141 ppb11,310
Springfield*Springfield, IL3 of 190.136 ppb119,395
University ParkDallas, TX5 of 60.133 ppb23,040
Pennsylvania American Coatesville*Coatesville, PA2 of 100.127 ppb30,299
City of Lewisville*Lewisville, TX7 of 120.123 ppb104,780
Murphysboro*Murphysboro, IL19 of 260.123 ppb10,941
City of LivingstonLivingston, TX5 of 60.117 ppb11,692
Harris County FWSD 51*Houston, TX10 of 120.101 ppb10,401
West Jefferson Waterworks District 2*Jefferson, LA5 of 250.100 ppb188,770
City of Texas CityTexas City, TX8 of 180.0989 ppb48,558
Greensburg Municipal Water Works*Greensburg, IN6 of 240.0967 ppb12,000
Walpole Water DepartmentWalpole, MA13 of 200.0945 ppb23,989
City of South HoustonSouth Houston, TX20 of 330.0942 ppb17,397
City of Midlothian*Midlothian, TX7 of 170.0924 ppb16,728
City of Sugar Land*Sugar Land, TX12 of 340.0924 ppb83,886
Harris County WCID 36Houston, TX6 of 120.0883 ppb11,065
Piqua City PWSPiqua, OH9 of 360.0871 ppb20,522
Effingham*Effingham, IL2 of 170.0829 ppb12,328
Johnston County - West*Smithfield, NC9 of 190.0826 ppb58,354
ClaytonClayton, NC9 of 190.0826 ppb19,822
City of MonroeMonroe, NC7 of 240.0818 ppb31,438
City of La MarqueLa Marque, TX2 of 60.0817 ppb15,154
City of Galveston*Galveston, TX2 of 60.0817 ppb50,180
Del-Co Water Company Inc.*Delaware, OH32 of 430.0810 ppb141,407
Johnston County - East*Smithfield, NC10 of 180.0800 ppb31,250
Lafourche Water District 1Lockport, LA4 of 460.0783 ppb78,760
East Fork SUDWylie, TX7 of 170.0753 ppb13,596
Town of ProsperProsper, TX7 of 170.0753 ppb22,650
City of Forney*Forney, TX7 of 170.0753 ppb19,122
City of Princeton*Princeton, TX7 of 170.0753 ppb16,932
Caddo Basin SUDGreenville, TX7 of 170.0753 ppb13,335
City of AllenAllen, TX7 of 170.0753 ppb102,762
City of RowlettRowlett, TX7 of 170.0753 ppb59,300
Town of Little Elm*Little Elm, TX7 of 170.0753 ppb41,796
City of Plano*Plano, TX7 of 170.0753 ppb277,720
City of GarlandGarland, TX7 of 170.0753 ppb236,786
City of SachseSachse, TX7 of 170.0753 ppb25,937
City of Frisco*Frisco, TX7 of 170.0753 ppb192,261
City of Mesquite*Mesquite, TX7 of 170.0753 ppb143,350
City of RichardsonRichardson, TX7 of 170.0753 ppb104,300
City of WylieWylie, TX7 of 170.0753 ppb44,418
City of McKinney*Mckinney, TX7 of 170.0753 ppb169,710
City of MurphyMurphy, TX7 of 170.0753 ppb20,361

* 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 Simazine, but it likely has the contaminant in its water supply.