Drinking Water Contaminants
Learn about 91 regulated contaminants found in US drinking water. Each listing includes health effects, EPA Maximum Contaminant Levels (MCL), common sources, and treatment methods.
Inorganic Chemicals
Lead
LEADDevelopmental delays in children, kidney problems, high blood pressure in adults
Arsenic
ARSENICSkin damage, circulatory system problems, increased risk of cancer
Nitrate
NITRATEBlue baby syndrome in infants, decreased oxygen-carrying capacity of blood
Nitrite
NITRITEBlue baby syndrome in infants
Fluoride
FLUORIDEBone disease, tooth discoloration in children
Copper
COPPERShort-term: gastrointestinal distress; long-term: liver or kidney damage
Barium
BARIUMIncreased blood pressure
Chromium (Total)
CHROMIUMAllergic dermatitis, liver and kidney damage
Chromium-6
CHROMIUM6Increased cancer risk, liver and kidney damage
Mercury
MERCURYKidney damage, nervous system disorders
Selenium
SELENIUMHair and fingernail loss, numbness, circulatory problems
Antimony
ANTIMONYIncreased blood cholesterol, decreased blood sugar
Beryllium
BERYLLIUMIntestinal lesions
Cadmium
CADMIUMKidney damage
Cyanide
CYANIDENerve damage, thyroid problems
Thallium
THALLIUMHair loss, kidney/intestine/liver damage
Asbestos
ASBESTOSIncreased risk of benign intestinal polyps
Total Hardness
TOTAL_HARDNESSNo direct health effects; scaling and soap inefficiency
Total Dissolved Solids
TDSTaste, hardness, corrosion
Sulfate
SULFATELaxative effect at high concentrations
Chloride
CHLORIDESalty taste, corrosion of pipes
Iron
IRONRusty color, metallic taste, staining
Manganese
MANGANESEBlack staining, neurological effects at high levels
Zinc
ZINCMetallic taste, nausea at high levels
Aluminum
ALUMINUMPossible neurological effects at very high levels
Perchlorate
PERCHLORATEThyroid gland dysfunction
Organic Chemicals
PFAS (Per- and Polyfluoroalkyl Substances)
PFASDevelopmental effects, liver damage, immune system effects, increased cancer risk
PFOA (Perfluorooctanoic Acid)
PFOACancer risk, liver damage, developmental effects
PFOS (Perfluorooctane Sulfonate)
PFOSCancer risk, thyroid effects, immune system effects
Total Trihalomethanes
TTHMLiver, kidney, or central nervous system problems, increased risk of cancer
Haloacetic Acids (HAA5)
HAA5Increased risk of cancer
Bromate
BROMATEIncreased risk of cancer
Chlorite
CHLORITEAnemia, nervous system effects
Benzene
BENZENEIncreased risk of cancer, anemia
Toluene
TOLUENENervous system, kidney, liver problems
Xylene
XYLENENervous system damage
Styrene
STYRENELiver, kidney, circulatory system problems
Vinyl Chloride
VINYL_CHLORIDEIncreased risk of cancer
Carbon Tetrachloride
CARBON_TETLiver problems, increased cancer risk
Dichloromethane
DICHLOROMETHANELiver problems, increased cancer risk
Trichloroethylene (TCE)
TCELiver problems, increased cancer risk
Tetrachloroethylene (PCE)
PCELiver problems, increased cancer risk
1,2-Dichloroethane
12DCAIncreased risk of cancer
1,1-Dichloroethylene
11DCELiver, kidney damage
cis-1,2-Dichloroethylene
CIS12DCELiver, kidney damage
trans-1,2-Dichloroethylene
TRANS12DCELiver, kidney damage
MTBE (Methyl tert-Butyl Ether)
METHYL_TBUTYLNervous system effects, possible cancer risk
Atrazine
ATRAZINECardiovascular system, reproductive problems
Simazine
SIMAZINEProblems with blood
Alachlor
ALACHLOREye, liver, kidney, spleen problems; increased cancer risk
Glyphosate
GLYPHOSATEKidney problems, reproductive difficulties
2,4-D
24DKidney, liver, adrenal gland problems
Dalapon
DALAPONMinor kidney changes
Endrin
ENDRINLiver problems
Lindane
LINDANELiver, kidney damage
Methoxychlor
METHOXYCHLORReproductive difficulties
Toxaphene
TOXAPHENEKidney, liver, thyroid problems; increased cancer risk
Polychlorinated Biphenyls (PCBs)
PCBSkin changes, thymus gland problems, immune deficiencies, cancer risk
Dioxin (2,3,7,8-TCDD)
DIOXINReproductive difficulties, increased risk of cancer
Pentachlorophenol
PENTACHLOROPHENOLLiver and kidney problems, increased cancer risk
DBCP (Dibromochloropropane)
DIBROMOCHLOROPROPANEReproductive difficulties, increased cancer risk
EDB (Ethylene Dibromide)
EDBLiver, stomach, reproductive problems; cancer risk
1,4-Dioxane
1_4_DIOXANEIncreased risk of cancer
GenX Chemicals
GENXLiver and kidney effects, cancer risk
Heptachlor
HEPTACHLORLiver damage, increased cancer risk
Heptachlor Epoxide
HEPTACHLOR_EPOXIDELiver damage, increased cancer risk
Oxamyl (Vydate)
OXAMYLSlight nervous system effects
Picloram
PICLORAMLiver problems
Dinoseb
DINOSEBReproductive difficulties
Hexachlorobenzene
HEXACHLOROBENZENELiver and kidney problems, cancer risk
Hexachlorocyclopentadiene
HEXACHLOROCYCLOPENTADIENEKidney, stomach problems
BHC-gamma (Lindane)
BHC_GAMMALiver, kidney damage
Di(2-ethylhexyl) adipate
DI2ETHYLHEXYL_ADIPATEWeight loss, liver problems, possible reproductive difficulties
Di(2-ethylhexyl) phthalate
DI2ETHYLHEXYL_PHTHALATEReproductive difficulties, liver problems, increased cancer risk
Microbial Contaminants
Total Coliform
COLIFORMIndicator of potentially harmful bacteria present
E. coli
ECOLIGastrointestinal illness, potential kidney failure
Giardia lamblia
GIARDIAGiardiasis: diarrhea, cramps, nausea
Cryptosporidium
CRYPTOSPORIDIUMCryptosporidiosis: diarrhea, vomiting
Legionella
LEGIONELLALegionnaires disease (pneumonia-like)
Turbidity
TURBIDITYIndicates potential microbial contamination, interferes with disinfection
Radionuclides
Radium-226
RADIUM226Increased risk of cancer
Radium-228
RADIUM228Increased risk of cancer
Radon
RADONIncreased risk of cancer
Uranium
URANIUMIncreased risk of cancer, kidney toxicity
Gross Alpha Particle Activity
GROSS_ALPHAIncreased risk of cancer
Gross Beta Particle Activity
GROSS_BETAIncreased risk of cancer
Strontium-90
STRONTIUM90Increased risk of cancer
Tritium
TRITIUMIncreased risk of cancer
Disinfectants & Byproducts
Chlorine
CHLORINEEye and nose irritation, stomach discomfort
Chloramine
CHLORAMINEEye and nose irritation, stomach discomfort, anemia
Chlorine Dioxide
CHLORINE_DIOXIDEAnemia, nervous system effects in infants