Cadmium in Drinking Water
Found in 638 water systems • heavy_metals
Updated September 2026 • Data from EWG & EPA
What is Cadmium and Why Does It Matter?
CADMIUM IN TAP WATER: WHAT YOU NEED TO KNOW
What Is Cadmium and Where Does It Come From?
Cadmium is a soft, silvery-white metal that doesn't belong in your drinking water. It enters water supplies through natural deposits in soil and rock, but human activity is the bigger culprit. Mining operations, metal smelting, and industrial manufacturing release cadmium into the environment. Old galvanized pipes and brass fixtures in homes can also leach cadmium into tap water, especially in areas with acidic water. Once cadmium contaminates groundwater or surface water, it's difficult to remove naturally. The metal accumulates over time and doesn't break down in the environment.
The Health Impact of Cadmium Exposure
Cadmium is a known carcinogen that damages your body even at low exposure levels. The EPA recognizes cadmium as a probable human carcinogen, while the International Agency for Research on Cancer (IARC) classifies it as a confirmed human carcinogen. Long-term exposure increases your risk of kidney damage, bone disease, and cancer of the lungs, prostate, and bladder. Children are especially vulnerable because their bodies absorb cadmium more efficiently than adults. Even small amounts accumulate in your kidneys and liver over years of drinking contaminated water. The EWG health guideline for cadmium is 0.04 ppb (parts per billion), which is 25 times stricter than the EPA's legal limit of 5 ppb. This gap exists because the EWG bases its guideline on cancer risk, while the EPA's standard focuses on kidney damage.
The Regulatory Gap: EPA vs. EWG Standards
The EPA's 5 ppb limit hasn't been updated since 1991, despite growing scientific evidence about cadmium's dangers. The EWG's 0.04 ppb guideline reflects current research on cancer risk at very low doses. This creates a significant problem: water can be "legal" under EPA standards but still pose health risks according to the EWG. Currently, 466 water systems across the United States exceed the EWG health guideline, with an average cadmium level of 0.391 ppb. The maximum detected level reached 9.0 ppb—225 times the EWG guideline and nearly twice the EPA legal limit. This shows that cadmium contamination is real and serious in many communities.
Where Cadmium Problems Are Worst
Cadmium contamination isn't random—it follows specific geographic patterns. Iowa leads the nation with 186 water systems exceeding the EWG guideline, followed by Florida with 75 systems, Colorado with 56, Missouri with 39, and California with 35. Iowa's agricultural region and historical mining activity create ideal conditions for cadmium contamination. Florida's naturally acidic groundwater dissolves cadmium from soil and rock more readily. Colorado's mining legacy and high-altitude terrain contribute to elevated levels. These states share common factors: either historical industrial activity, natural geology that mobilizes cadmium, or both. If you live in these regions, testing your water is especially important.
How to Remove Cadmium From Your Water
The good news: cadmium removal is straightforward with the right filtration system. Reverse osmosis (RO) systems remove up to 99.9% of cadmium from tap water and are the most reliable option for home use. Activated carbon filters provide some reduction but aren't as effective as RO. Ion exchange water softeners can also remove cadmium, particularly if your water is hard. For maximum protection, combine methods: use a sediment pre-filter to extend the life of your RO membrane, then add a carbon filter for taste and odor. If you're on a municipal water system, request your water quality report and check whether cadmium levels exceed the EWG guideline. If they do, installing a point-of-use RO system under your kitchen sink protects your drinking and cooking water. Testing your water is the first step—you can't fix a problem you don't know exists.
Regulatory Standards for Cadmium
| Standard | Level | Notes |
|---|---|---|
| EWG Health Guideline | 0.04 ppb | Stricter, based on latest science |
| EPA Legal Limit (MCL) | 5 ppb | Legally enforceable standard |
| Average Detected Level | 0.39 ppb | Across all tested systems |
| Highest Detected Level | 9 ppb | Worst-case system |
Cities With the Highest Cadmium Levels
| # | City | Detected Level | People Served |
|---|---|---|---|
| 1 | Po Box 70, WA | 9 ppb | 5,305 |
| 2 | Weber City, VA | 6.33 ppb | 5,412 |
| 3 | Abingdon, VA | 6.33 ppb | 142 |
| 4 | Weber City, VA | 5 ppb | 437 |
| 5 | Lakeside, AZ | 4.20 ppb | 25 |
| 6 | San Luis, CO | 4.20 ppb | 45 |
| 7 | Berlin, NY | 4 ppb | 0 |
| 8 | Capulin, CO | 4 ppb | 0 |
| 9 | Sneedville, TN | 3.30 ppb | 0 |
| 10 | Mulberry, FL | 3 ppb | 150 |
| 11 | Glendale, AZ | 3 ppb | 28 |
| 12 | Denver, NC | 2.83 ppb | 134 |
| 13 | Poughkeepsie, NY | 2.75 ppb | 1,100 |
| 14 | La Junta, CO | 2.53 ppb | 70 |
| 15 | Park Hills, MO | 2.52 ppb | 8,587 |
States Most Affected by Cadmium
How to Remove Cadmium From Your Water
Basic activated carbon filters are ineffective against cadmium ions because activated carbon has minimal affinity for dissolved heavy metal cations; ion exchange or reverse osmosis is required.
Standard pitcher filters and carbon-only filters do not reliably remove Cadmium. A reverse osmosis system with NSF/ANSI 58 certification is the most reliable solution.
Cadmium requires ion-exchange resins or reverse osmosis for effective removal; activated carbon provides negligible protection against this carcinogenic heavy metal.
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Shop Hydrogen FlaskFrequently Asked Questions
Is Cadmium in my drinking water?
Cadmium was detected in 638 water systems across the US. Check your city's water quality report to see if it affects your water supply.
What are the health effects of Cadmium in water?
Cadmium has been associated with various health concerns at elevated levels. The EWG has set health guidelines that are typically stricter than EPA legal limits.
Which city has the most Cadmium in its water?
Based on our analysis, Po Box 70, WA has the highest detected levels of Cadmium in its water supply.
How do I remove Cadmium from my water?
Reverse osmosis (RO) systems are generally the most effective at removing this contaminant. Check the filtration recommendations section for specific guidance.
Related Contaminant Guides
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: September 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
