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Shortlist

Contaminant

Nitrite in drinking water

Also listed as Nitrite (as N) · Nitrite-N · Nitrite as Nitrogen

A close cousin of nitrate from fertilizer and sewage. Like nitrate, it’s especially dangerous for infants (“blue-baby syndrome”).

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.
11 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 · 8 sections
  1. 01Reference values
  2. 02Is it in my water?
  3. 03Testing
  4. 04Water filters
  5. 05Evidence
  6. 06Next steps
  7. 07Ask about nitrite
  8. 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
1 ppm

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 (1 mg/L as N) · 40 CFR §141.62
Health-based goal · MCLGFederal · not enforceable
1 ppm

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 1 mg/L · 40 CFR §141.51

Check your result’s basis

Says “as N”
Comparable to a reference stated as nitrogen.
Says “as NO₃”
A different, larger scale. Don’t compare directly.
Doesn’t say
We won’t compare it to any number. Ask your lab which basis they used.
Your stateNot held yetStates may set their own references. We don’t hold a state reference for nitrite 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 nitrite

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 nitrite

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

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

Find a fit in FinderRead 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 nitrite yet.

How we read evidence →

Next steps

Take the next step

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

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 Nitrite

Answers draw on cited public-health sources and the filters certified to reduce Nitrite. 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 (1 mg/L as N)
  2. 2Regulatory reference40 CFR §141.51EPA National Primary Drinking Water Regulations — MCLG 1 mg/L
  3. 3Knowledge BaseOverview of Drinking Water Treatment TechnologiesUS EPA (SDWA program)
  4. 4Knowledge BaseAddressing Nitrate with the Drinking Water State Revolving FundUS EPA (Office of Ground Water and Drinking Water)
  5. 5Knowledge BaseNitrate in Well WaterMinnesota Department of Health
  6. 6Knowledge BaseNitrate/Nitrite Fact Sheet (Contaminant in Water: Maximum Contaminant Level)Water Quality Association (WQA)
  7. 7Knowledge BaseNitrate/Nitrite Toxicity: What Are U.S. Standards and Regulations for Nitrates and Nitrites Exposure?ATSDR / CDC (Case Studies in Environmental Medicine)
  8. 8Knowledge BaseNitrate/Nitrite Toxicity: What Are the Health Effects from Exposure to Nitrates and Nitrites?ATSDR / CDC (Case Studies in Environmental Medicine)
  9. 9Knowledge BaseToxicological Profile for Nitrate and NitriteATSDR / CDC
  10. 10Knowledge BaseGuidelines for Testing Well WaterCDC (Division of Drinking Water Safety)
  11. 11Knowledge BaseNSF/ANSI 58: Reverse Osmosis Drinking Water Treatment SystemsNSF International

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

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