Mercury in Tap Water
Inorganic mercury is a toxic metal that reaches water from natural deposits, industrial discharge, and runoff. The drinking-water rule addresses inorganic mercury, distinct from the methylmercury that builds up in fish.
Natural erosion of mineral deposits; discharge from refineries and factories; runoff from landfills and croplands.
- 1Natural mineral deposits
- 2Industrial discharge
- 3Landfill and cropland runoff
A result is read with its context
This contaminant is tracked through federal and state compliance monitoring. This figure is for inorganic mercury in water and is separate from fish-consumption advisories. PurityMap does not yet publish a per-system measured value for Mercury; this page is a reference explainer. To learn what is in your own water, check your utility’s Consumer Confidence Report (CCR) or use a certified home test.
- Above reference
- Evidence exceeds a reference level.
- Detected
- This substance was found in the monitoring record. Being present is not the same as being above a reference level, and this signal does not say which.
- Not detected
- Somebody looked and the laboratory reported nothing above its reporting limit. This is a result, and it is not the same as nobody looking.
- Not monitored
- No sampling for this substance has been reported for this system. Nothing is known either way, and an empty row is not a clean one.
No city results or violations published yet
- MeasurementsPendingNo per-system values
PurityMap does not yet publish a measured value for mercury.
- ViolationsCheckedNone on the federal record
No city in PurityMap’s record has a mercury violation in EPA SDWIS since 2016.
- CitiesPendingNo detections on record
No city in PurityMap’s record shows mercury detected.
This fills in as monitoring data is published. Until then, your utility’s Consumer Confidence Report lists its results, or use a certified home test.
What can carry a mercury reduction claim
- Reverse osmosis
Semi-permeable membrane separation removing dissolved minerals, heavy metals, and persistent fluorinated chemicals down to 0.0001 microns.
- Activated carbon (GAC)
Highly porous adsorption media targeting chlorine, disinfection byproducts, volatile organic compounds, and organic chemicals.
- Coagulation / filtration
Boiling does not remove a dissolved chemical compound and can concentrate it. Many pitcher and refrigerator filters carry no verified claim for a compound like this at all.
A finding establishes the need, the need names the capability, the capability requires a verified certification. No product appears before that sequence completes. Filter Finder →
Frequently asked
Answers cite the same records as the page. How PurityMap analyzes water data
Inorganic mercury is a toxic metal that reaches water from natural deposits, industrial discharge, and runoff. The drinking-water rule addresses inorganic mercury, distinct from the methylmercury that builds up in fish.
The enforceable federal limit is 0.002 mg/L / 2 µg/L (MCL). The health-based goal (MCLG) is 2 µg/L. PurityMap reads every measurement against its stated benchmark and never sets its own.
Natural mineral deposits, Industrial discharge, Landfill and cropland runoff.
Long-term exposure to inorganic mercury above the limit is associated with kidney effects. The enforceable limit is set well below levels linked to harm.
Treatment technologies commonly certified to reduce Mercury include Reverse osmosis, Activated carbon (GAC), Coagulation / filtration. Match the exact certified claim to your water before buying. Holding a format is not the same as holding the claim.