EWG's Tap Water Database — 2019 UPDATE


Mercury (inorganic)

Status: National drinking water standard exists


Mercury is a potent neurotoxin that also damages the kidneys and other internal organs. Mercury enters drinking water from industrial pollution, mining wastes and coal-fired power plants.




states detected


utilities detected

7.0 million

people served


states over health guideline


utilities over health guideline


people served over health guideline

Health concerns for mercury (inorganic)

Harm to the brain and nervous system

Harm to fetal growth and child development

Harm to the kidney

Harm to the immune system

State and national drinking water standards and health guidelines

EWG Health Guideline 1.2 ppb

The EWG Health Guideline of 1.2 ppb for mercury (inorganic) 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 harm to internal organs.

EPA Maximum Contaminant
Level (MCL) 2 ppb

The legal limit for inorganic mercury, established in 1991, was based on toxicity studies conducted in laboratory animals in the 1970s and 1980s. This limit does not include any additional consideration of children’s health.

ppb = parts per billion

States reporting mercury (inorganic) in drinking water

State UtilitiesPeople Served UtilitiesPeople Served
New Jersey12501041,122,300
South Dakota002158,926
New York001672,540
North Carolina001550,227
South Carolina00439,673
West Virginia00615,597
New Hampshire00216,138

Filtering technologies that reduce mercury (inorganic)

carbon filter icon

Activated Carbon

reverse osmosis icon

Reverse Osmosis

Utilities with the highest amounts of mercury (inorganic), 2015-2017

UtilityLocationTestsAverage levelPeople served
Picnic Grove Mobile HomesMalaga, NJ2 of 22.10 ppb250
Murrieta/hernandez FarmsKerman, CA7 of 71.76 ppb29
Choctaw Valley Mutual Water CompanyBakersfield, CA1 of 11.40 ppb44
Lakeview Estates Mobile Home CommunityMt. Gilead, OH1 of 11.30 ppb145
Bethel Heights Water SystemBethel, AK1 of 11.29 ppb2,220
Ponderosa SubdivisionColorado Springs, CO1 of 11.000 ppb115
Hidden Valley Light AssociationColdwater, MS1 of 11.000 ppb53
City of Log CabinMalakoff, TX1 of 11.000 ppb714
Grays Harbor Co. Water District 2Aberdeen, WA1 of 11.000 ppb3,507
Stoney Field Mobile Home ParkPittsford, NJ1 of 10.976 ppb200
Daggett Community Services DistrictDaggett, CA1 of 20.950 ppb795
Cassatt Water Kershaw-lee Company RWACassatt, SC12 of 220.898 ppb24,879
Western Greene County R W DWalcott, AR13 of 170.861 ppb6,394
Twin Pines Health Care CenterWest Grove, PA1 of 10.800 ppb120
Manderly Mobile Home ParkCrystal City, MO1 of 10.720 ppb220
Sherwood Retirement and Personal Care HomeCanton, PA1 of 10.719 ppb32
Viejo San AcacioSan Luis, CO1 of 10.700 ppb45
Shady Pines Camping ResortGalloway, NJ1 of 10.639 ppb160
Louisburg PWSLouisburg, MO1 of 10.630 ppb122
Lake Tarpon Mobile Home VillagPalm Harbor, FL1 of 50.620 ppb1,285
Vineland Water & Sewer UtilityVineland, NJ9 of 130.614 ppb36,250
SoutheastFrostproof, FL1 of 30.600 ppb2,828
Garcia Domestic WuaSan Luis, CO1 of 10.600 ppb100
Twin Pines Mobile Home ParkLockbourne, OH1 of 10.600 ppb75
Md#46 Ahwahnee ResortsMadera, CA2 of 20.590 ppb300
Yosemite Westlake Mobile EstatesGreeley Hill, CA1 of 10.570 ppb75
Birdsboro Municipal Water AuthorityBirdsboro, PA1 of 30.567 ppb5,353
Circle C Mobile Home ParkVilla Ridge, MO1 of 10.550 ppb90
Town & Country Water CompanyBakersfield, CA1 of 10.540 ppb85
Farmington ManorFarmington, MO2 of 30.510 ppb60
Ridgeview Mobile Home ParkRising Sun, PA1 of 10.500 ppb55
Doe Run Mobile Home ParkEast Earl, PA1 of 10.500 ppb29
East Feliciana Wwks District 7Clinton, LA2 of 40.500 ppb2,766
Harrison City PWSHarrison, OH1 of 10.500 ppb10,000
Sunrise Hill EstatesBarrington, ME1 of 10.500 ppb100
Jefferson Water and Sewer District Public Water SystemBlacklick, OH1 of 10.500 ppb9,054
Rogue Creek UtilitiesFarmington, MO3 of 30.493 ppb200
Marquez RentalFirebaugh, CA1 of 10.480 ppb50
Wrightstown Municipal Utilities AuthorityWrightstown, NJ1 of 10.465 ppb748
La Caleta EstatesWimberley, TX1 of 10.450 ppb152
Seguro Water Company*San Antonio, TX1 of 10.450 ppb0
Nottingham Towers ApartmentsNarberth, PA1 of 10.400 ppb175
Whispering Willow Mobile Home Park Public Water SystemBirmingham, OH1 of 20.400 ppb193
Kiskatom Mobile Home ParkCatskill, NY1 of 10.400 ppb100
Calamus EstatesRonks, PA1 of 10.400 ppb140
Elnora Water WorksElnora, IN1 of 10.400 ppb663
Casa Verde Manufactured Home CommunityTampa, FL2 of 20.400 ppb1,250
Chambersburg Boro Water Sys*Chambersburg, PA1 of 30.400 ppb17,500
Bloomington WaterworksBloomington, WI1 of 10.400 ppb682
Md#42 Still MeadowMadera, CA1 of 20.385 ppb100

* 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 Mercury (inorganic), but it likely has the contaminant in its water supply.

UtilityLocationTestsAverage levelPeople served
Cassatt Water Kershaw-lee Company RWACassatt, SC12 of 220.898 ppb24,879
Vineland Water & Sewer UtilityVineland, NJ9 of 130.614 ppb36,250
Harrison City PWSHarrison, OH1 of 10.500 ppb10,000
Chambersburg Boro Water Sys*Chambersburg, PA1 of 30.400 ppb17,500
Peoples Water Service CompanyPensacola, FL1 of 50.360 ppb34,352
Monroe Twp MUAWilliamstown, NJ50 of 780.318 ppb36,100
City of ClermontClermont, FL1 of 20.300 ppb11,265
City of Lynn Haven Water SystemLynn Haven, FL1 of 20.300 ppb20,740
Onalaska WaterworksOnalaska, WI4 of 50.280 ppb18,000
Hamilton Township MUA*Mays Landing, NJ2 of 50.266 ppb21,720
Sioux Falls*Sioux Falls, SD1 of 10.200 ppb158,800
University of West FloridaPensacola, FL1 of 20.200 ppb12,000
Millville Water DepartmentMillville, NJ3 of 40.193 ppb27,500
City of Cocoa*Cocoa, FL1 of 30.167 ppb285,352
Epcor Water - MohaveYoungtown, AZ2 of 90.144 ppb36,330
Municipal Authority of Westmoreland County - Yough Plant*Greensburg, PA1 of 30.133 ppb140,000
City of Albemarle*Albemarle, NC1 of 60.128 ppb16,500
Columbia Water CompanyColumbia, PA1 of 30.127 ppb21,500
Platteville WaterworksPlatteville, WI1 of 20.1000 ppb12,268
City of Temple Terrace UtilityTemple Terrace, FL2 of 20.1000 ppb31,062
Schuylkill County. Municipal Authority*Pottsville, PA1 of 100.0930 ppb31,850
Northern Kentucky Water District*Ft Thomas, KY3 of 120.0917 ppb199,460
Hammonton Water DepartmentHammonton, NJ1 of 30.0900 ppb12,153
Point Pleasant Water DepartmentPoint Pleasant, NJ1 of 40.0888 ppb19,600
Willingboro MUA*Willingboro, NJ3 of 40.0825 ppb35,000
EurekaEureka, MO1 of 60.0800 ppb10,000
City of Corsicana*Corsicana, TX2 of 60.0763 ppb23,770
Wilkinsburg-penn Joint Water Authority*Wilkinsburg, PA1 of 40.0750 ppb120,000
Winslow Township DMU*Braddock, NJ4 of 80.0744 ppb39,174
La Crosse WaterworksLa Crosse, WI4 of 110.0727 ppb53,000
Auburn Water SystemCrestview, FL5 of 70.0714 ppb22,015
NJ American Water - Atlantic CountyEgg Harbor, NJ2 of 160.0688 ppb120,146
Ashland Water Works*Ashland, KY1 of 30.0667 ppb44,402
City of San LuisSan Luis, AZ6 of 60.0667 ppb27,800
City of Havre De Grace*Havre De Grace, MD1 of 30.0667 ppb14,000
Granger - Hunter Improvement DistrictDraper, UT4 of 170.0588 ppb121,083
California American Water Company - MontereyMonterey, CA3 of 1020.0578 ppb96,754
Municipality of Anchorage*Anchorage, AK1 of 350.0514 ppb221,351
Long Neck Water CompanyLong Neck, DE2 of 210.0476 ppb11,180
City of ChandlerChandler, AZ1 of 310.0419 ppb247,328
City of Clinton*Clinton, NC1 of 100.0400 ppb12,410
Florence Township Water DepartmentFlorence, NJ1 of 10.0370 ppb11,214
Breezy Hill WDGraniteville, SC1 of 150.0353 ppb13,692
Longport Water DepartmentLonport, NJ1 of 10.0350 ppb10,777
United Water Toms RiverToms River, NJ1 of 220.0341 ppb123,184
City of Tacoma*Tacoma, WA1 of 210.0333 ppb315,777
Okeechobee Utility AuthorityOkeechobee, FL1 of 30.0333 ppb20,000
East Milton Water SystemMilton, FL1 of 60.0333 ppb11,295
Cape May Water & Sewer*Cape May, NJ1 of 10.0330 ppb35,000
West Hwy 80 Ark Road WSWest Monroe, LA2 of 80.0300 ppb13,386

* 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 Mercury (inorganic), but it likely has the contaminant in its water supply.