Contaminant

Selenium in drinking water

Also listed as Se

An essential trace mineral that becomes toxic in excess. It occurs naturally in some groundwater and, at high levels, affects circulation and the nervous system.

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.

2 sources

01Check your water systemWater Check · system results, not your tap 02Test your tapHow to get a reliable result 03Treatment approachesWhat can reduce it at the tap

On this page · 8 sections

01Reference values
02Is it in my water?
03Testing
04Water filters
05Evidence
06Next steps
07Ask about selenium
08References

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

50 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 (0.05 mg/L) · 40 CFR §141.62

Health-based goal · MCLGFederal · not enforceable

50 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 0.05 mg/L · 40 CFR §141.51

Your stateNot held yetStates may set their own references. We don’t hold a state reference for selenium 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 selenium

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

01Use a certified labA state-certified lab, or a kit that sends samples to one.
02Follow the sampling stepsHow and when you collect the water changes the result.
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 selenium

None qualify

No products currently qualify for a selenium pick here.

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

Find a fit in Finder Read treatment approaches

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 selenium yet.

How we read evidence →

Next steps

Take the next step

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

Ask about selenium

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 Selenium

Answers draw on cited public-health sources and the filters certified to reduce Selenium. 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

1Regulatory reference40 CFR §141.62EPA NPDWR MCL (0.05 mg/L)
2Regulatory reference40 CFR §141.51EPA National Primary Drinking Water Regulations — MCLG 0.05 mg/L

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