"Heavy metals" is a broad search phrase. In drinking water, the useful question is more specific: which metal, from which source, at what level, and what standard or action level applies?
Common metals people ask about
| Metal | Why homeowners test | First clue |
|---|---|---|
| Lead | Old service lines, faucets, fixtures, and solder can contribute lead at the tap. | Older home, utility notice, lead service line inventory, or pipe material clues. |
| Copper | Corrosion of household plumbing can release copper. | Blue-green staining, plumbing age, or corrosive water conditions. |
| Arsenic | EPA lists natural deposits as a source; private wells can need local testing. | Private well, local geology, or health department guidance. |
| Cadmium/chromium/mercury | EPA regulates these inorganic chemicals in public water systems. | Industrial context, local source-water issue, or lab panel recommendation. |
What to test first
- Public water: read the Consumer Confidence Report and ask the utility which metals were detected or monitored.
- Private well: ask the county/state program which local contaminants are common. EPA says private well owners are responsible for safe household drinking water.
- Older plumbing: prioritize lead and copper, then choose filters only after you know the target contaminant.
Do not buy a broad "heavy metals" filter because the phrase sounds scary. Test the water, identify the contaminant, then verify the exact filter model against the certification claim.