Cadmium in Drinking Water
Cadmium is a toxic heavy metal that enters drinking water primarily from industrial contamination, mining operations, and corrosion of galvanized steel pipes — not typically from natural geological sources. The EPA MCL is 5 ppb. Cadmium is an IARC Group 1 human carcinogen and accumulates in kidney tissue over decades, causing irreversible kidney damage. It is one of the most persistent environmental contaminants because it remains toxic in the body for 10–30 years after exposure stops.
Quick Answer
Cadmium (Cd) is a soft, bluish-white metal that occurs naturally in the earth's crust primarily in association with zinc ores. It has been widely used in nickel-cadmium batteries, pigments, metal coatings, and plastic stabilizers. Industrial use has declined significantly since the 1980s as health hazards became clear, but legacy contamination from zinc smelting, mining operations, and cadmium-plated materials persists. In plumbing, cadmium enters water from galvanized steel pipes (which use zinc coatings containing trace cadmium) and from brass fittings. Cadmium's half-life in the human body is 10–30 years — longer than almost any other environmental contaminant.
Why Is Cadmium in Drinking Water a Concern?
The primary concern with cadmium is its extraordinary persistence in the body. Once absorbed, cadmium accumulates in the kidneys where it damages tubular cells progressively over decades. The damage is often silent until a significant fraction of kidney function has been lost. 'Itai-itai' disease in Japan — caused by cadmium-contaminated rice irrigation water from a zinc mine — documented severe cadmium toxicity including kidney failure and bone disease in a large population, establishing the long-term consequences of chronic cadmium exposure.
People who live near zinc mines, smelters, or cadmium battery production facilities face the highest industrial exposure. Well owners near mining operations in Colorado, Idaho, Montana, and parts of the Appalachian region face elevated groundwater risk. Homes with galvanized steel plumbing or older brass fixtures (which may contain cadmium as a trace impurity) have a lower-level but ongoing exposure pathway. Smokers have significantly higher cadmium body burden from tobacco, which concentrates cadmium from soil.
Health Effects of Cadmium in Drinking Water
Kidney tubular dysfunction and progressive nephrotoxicity — the primary chronic health effect; kidney damage from cadmium is largely irreversible
IARC Group 1 human carcinogen — lung cancer (primarily from inhalation), kidney cancer, and possible prostate cancer association
Itai-itai disease (Japan outbreak): severe kidney failure, extreme bone pain, multiple fractures, and osteoporosis from combined cadmium and low calcium/vitamin D exposure
Bone demineralization with chronic high exposure — cadmium interferes with calcium metabolism
No acute symptoms at concentrations found in drinking water — all effects are from long-term accumulation
Body burden accumulates over decades; effects may not manifest until middle age even with childhood exposure
How Does Cadmium Get Into Drinking Water?
Industrial contamination from zinc mining and smelting — cadmium occurs with zinc ore and is released during processing
Nickel-cadmium battery manufacturing and disposal
Galvanized steel plumbing — zinc coatings contain trace cadmium that can leach into water
Phosphate fertilizers — contain trace cadmium from phosphate rock; long-term agricultural application can build up cadmium in soil and shallow aquifers
Landfill leachate from cadmium-containing consumer products
Legacy industrial contamination near paint pigment and plastic stabilizer manufacturing sites
Regulatory Limit
EPA Maximum Contaminant Level (MCL)
5 ppb (0.005 mg/L)
The EPA MCL for cadmium is 5 micrograms per liter (µg/L), or 5 ppb, set in 1992. The MCLG is 5 µg/L — unlike lead or arsenic, the EPA has not set a MCLG of zero for cadmium in water, though cadmium is a known human carcinogen. The World Health Organization guideline is 3 µg/L — more stringent than the U.S. standard.
How to Test for Cadmium in Your Water
Cadmium testing requires a certified laboratory metals panel — it is not included in standard water quality tests. A cadmium-specific test costs $15–$30; a comprehensive metals panel including cadmium typically runs $75–$150. Well owners near mining operations, smelters, or industrial sites in metal-producing states should include cadmium in baseline testing. Homes with galvanized steel plumbing should test as part of a comprehensive metals assessment.
How to Remove Cadmium from Drinking Water
These treatment methods have demonstrated effectiveness for Cadmium removal.
Reverse Osmosis
Reverse osmosis (RO) is the most comprehensive point-of-use water treatment technology available for residential use. It removes 90–99% of dissolved contaminants including PFAS, lead, arsenic, nitrates, and disinfection byproducts by forcing water through a semi-permeable membrane with pores of approximately 0.0001 microns.
Activated Carbon
Activated carbon is the most widely used residential water treatment technology. It removes chlorine, taste and odor compounds, disinfection byproducts, many volatile organic compounds (VOCs), and — with NSF/ANSI 53 certification — lead and some PFAS. It is available as pitcher filters, under-sink units, and whole-house systems.
Frequently Asked Questions
Related Pages
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Quick Reference
Category
Heavy Metals
Risk Level
moderate
EPA Limit
5 ppb (0.005 mg/L)
Most at Risk
People who live near zinc mines, smelters, or cadmium battery production facilities face the highest industrial exposure.
Well Water Relevant
Yes
Cadmium by State
Treatment Options