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Shortlist

Contaminant

Mercury in drinking water

A heavy metal that harms the nervous system. It enters water from industry and runoff.

This page can’t tell you what’s in your tap water.
Only a test of water from your own tap can. Public-system results describe the system, not your home.
8 sources
01Check your water systemWater Check · system results, not your tap02Test your tapHow to get a reliable result03Treatment approachesWhat can reduce it at the tap
On this page · 9 sections
  1. 01Reference values
  2. 02Is it in my water?
  3. 03Testing
  4. 04Water filters
  5. 05Treatment
  6. 06Evidence
  7. 07Next steps
  8. 08Ask about mercury
  9. 09References
Reference values

An enforceable limit for public water systems.

Each value says what kind of reference it is, and they mean different things. A lower or missing number never means water is safe.

Enforceable limit · MCLFederal · public water systems
2 ppb

The highest level allowed in water a public system delivers. A legal limit, not a health goal.

Applies to
Water delivered by public water systems, not private wells
Status
In force
Source
EPA NPDWR MCL (0.002 mg/L) · 40 CFR §141.62
Health-based goal · MCLGFederal · not enforceable
2 ppb

The level below which no known health risk is expected. A goal, not a limit.

Applies to
Set alongside the rule as a public-health goal
Status
Published goal
Source
EPA National Primary Drinking Water Regulations — MCLG 0.002 mg/L · 40 CFR §141.51
Your stateNot held yetStates may set their own references. We don’t hold a state reference for mercury yet.
Is it in my water?

Only a test of your own tap can tell.

Choose what you have. We’ll show what it can and can’t tell you.

If you haven’t tested
Nobody can tell without a measurement, including us.

Three things you can do, in this order.

Test water from your tapThis is the only way to know your level. Testing guidance ↓See what your system reportsSystem results aren’t a tap measurement. Open Water Check →On a private well?Public-system reports don’t cover wells. Open Well Water →
Testing

How to test your tap water for mercury

Utilities sample to check system compliance. Your result reflects your own pipes and fixtures.

  1. 01Use a certified labA state-certified lab, or a kit that sends samples to one.
  2. 02Follow the sampling stepsHow and when you collect the water changes the result.
  3. 03Check the reportIt should state units and the detection limit.
Certified labNot sponsored
Use a state-certified labYour state keeps a list of labs certified for drinking water.

Choosing a filter for mercury

None qualify
No products currently qualify for a mercury pick here.

Nothing in our database has a mercury claim for an exact configuration we can verify.

Find a fit in FinderRead treatment approaches
Treatment

How to reduce mercury in water

Function: ReduceApproaches that can lower mercury at the tap.
How to reduce mercuryCarbon filters certified under NSF/ANSI 53 and reverse osmosis under 58 are the tested routes. Look for a claim that names mercury specifically rather than a generic metals claim.
Whole-house systems and point-of-use filters treat different water. A whole-house system treats water where it enters the home; a point-of-use filter treats the tap it’s installed on. Check which one a claim is for.
Evidence

What the evidence means

We keep evidence types apart. A result for one configuration never stands in for another, and we never average across types.

No product in our database holds a reduction record for mercury yet.

How we read evidence →

Next steps

Take the next step

Match a system to your homeFinder asks about your home first. It suggests mercury as a starting point, and nothing counts until you confirm it.
Ask about mercury

Still have a question?

Answers come only from WaterDecoder’s reviewed sources and show citations. Ask can’t interpret your test result or choose a product. Don’t include personal details.

AI assistant

Ask about Mercury

Answers draw on cited public-health sources and the filters certified to reduce Mercury. Every source is linked, and if the sources don’t cover a question, the answer says so.

Questions to start with

Educational information from cited sources. Not medical or professional advice.

References

Where these facts come from

  1. 1Regulatory reference40 CFR §141.62EPA NPDWR MCL (0.002 mg/L)
  2. 2Regulatory reference40 CFR §141.51EPA National Primary Drinking Water Regulations — MCLG 0.002 mg/L
  3. 3Knowledge BaseOverview of Drinking Water Treatment TechnologiesUS EPA (SDWA program)
  4. 4Knowledge BaseMercury: Treatment TechnologiesUS EPA (hosted via CLU-IN)
  5. 5Knowledge BaseTechnical Application Bulletin: MercuryWater Quality Association (WQA)
  6. 6Knowledge BaseGuidelines for Testing Well WaterCDC (Division of Drinking Water Safety)
  7. 7Knowledge BaseGuidelines for Drinking-water Quality - Mercury (chemical fact sheet)World Health Organization (WHO)
  8. 8Knowledge BaseHealth Effects of Exposures to Mercury / Basic Information about MercuryUS EPA

Written and maintained by WaterDecoder. A review date appears only once we have confirmed one.

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