Water Contaminants: What's in Your Tap Water
Independent reference guides for the most common contaminants found in US drinking water. Each guide covers health effects, EPA regulations, testing methods, and treatment options.
Minerals
Water Hardness
Water hardness is caused by dissolved calcium and magnesium. It is not a health risk, but at levels above 120 PPM it causes scale buildup, applianc...
Total Dissolved Solids
TDS measures the total concentration of dissolved minerals, salts, and metals in water. It is not a health hazard at typical levels. The EPA second...
Fluoride
Fluoride is added to most US municipal water at 0.7 PPM to prevent tooth decay. The EPA limit is 4 PPM. At levels above 2 PPM, fluoride can cause d...
Chemicals
PFAS
PFAS are synthetic chemicals found in the drinking water of an estimated 110 million Americans. The EPA set a legal limit of 4 parts per trillion f...
Nitrate
Nitrate is a common groundwater contaminant from agricultural runoff and fertilizers. The EPA limit is 10 PPM. At levels above this, nitrate is dan...
Trihalomethanes
Trihalomethanes (THMs) are disinfection byproducts formed when chlorine reacts with organic matter in water. The EPA limit is 80 PPB. Long-term exp...
Heavy Metals
Lead
Lead in drinking water comes from pipes, solder, and fixtures, not the water supply. There is no safe level of lead exposure. The EPA action level ...
Arsenic
Arsenic is a naturally occurring toxic element found in groundwater across many US regions. The EPA limit is 10 PPB but the health goal is zero. Lo...
Iron
Iron in water is not a health hazard at typical levels but causes orange or brown staining, metallic taste, and stained laundry. The EPA secondary ...