Is nitrate in drinking water a widespread problem in the U.S.?

Yes. Nitrate contamination is one of the most common drinking water quality issues in the United States, particularly in agricultural regions. The EPA estimates millions of people are served by public water systems that have detected nitrate, and private well users in farming areas face even greater risk. Elevated nitrate most often traces to fertilizer runoff, animal waste, and failing septic systems.

What is the legal limit for nitrate in U.S. drinking water?

The EPA Maximum Contaminant Level (MCL) for nitrate is 10 mg/L measured as nitrate-nitrogen (NO3-N). This is a hard enforceable limit — unlike lead's 'action level.' Public water systems are required to notify customers promptly and take corrective action if nitrate exceeds 10 mg/L.

How does nitrate get into drinking water?

Nitrate enters drinking water through several pathways: agricultural fertilizer and animal waste runoff that leaches into groundwater and surface water; septic system effluent near water sources; and natural soil deposits in some regions. Surface water supplies can spike after rain events in agricultural areas. Groundwater wells may show persistent elevated nitrate that changes slowly over seasons.

Who is most at risk from nitrate in drinking water?

Infants under six months of age face the most serious risk. High nitrate interferes with the blood's ability to carry oxygen, causing a condition called methemoglobinemia — commonly called 'blue baby syndrome' — which can be life-threatening. Pregnant residents, people with certain enzyme deficiencies, and immunocompromised individuals also face elevated concern. Adults in good health generally tolerate nitrate at levels at or near the MCL, but long-term exposure at elevated levels has been associated with increased cancer risk in some studies.

What type of filter removes nitrate from drinking water?

Reverse osmosis systems certified to NSF/ANSI Standard 58 are the most accessible residential option for nitrate removal, achieving 85–95% reduction. Distillation units and anion exchange systems also remove nitrate effectively. Standard activated carbon (pitcher or under-sink) filters do NOT remove nitrate and should not be used for this purpose.

Are private wells regulated for nitrate?

No. Private wells are not regulated under the Safe Drinking Water Act. Homeowners with private wells are responsible for testing their own water. In agricultural regions, state health departments and land-grant universities often offer subsidized nitrate testing. The EPA and CDC recommend private well owners test for nitrate at least once per year.

How do I find out if my utility has had nitrate violations?

Look up your utility on this site using the ZIP lookup below. Each utility page shows violations from EPA's SDWIS database, including nitrate violations, the year they occurred, and whether they are open or resolved. You can also review your utility's most recent Consumer Confidence Report (CCR), which must disclose any MCL violations in the past year.

Moderate–High RiskAgricultural Contaminant

Nitrate in Drinking Water

Q: Does boiling water remove nitrate?

No. Boiling does not remove nitrate and actually concentrates it by evaporating water. Nitrate is only effectively removed by reverse osmosis (NSF/ANSI Standard 58), distillation, or ion exchange — not by boiling, carbon filtration, or UV treatment.

Nitrate is one of the most common drinking water contaminants in the United States. It enters water primarily from fertilizer runoff, animal waste, and septic systems — and poses an immediate, life-threatening risk to infants under six months.

Source: EPA, CDC · Last reviewed: 2025-01-01 · Data: official EPA SDWIS records

Quick Answer

Is nitrate in drinking water a real concern?

Yes — particularly in agricultural states and for households on private wells. The EPA's MCL for nitrate is 10 mg/L as nitrogen. Exceeding this level poses an immediate risk to infants under six months, who can develop methemoglobinemia (blue baby syndrome) — a potentially fatal condition. Long-term elevated exposure has been linked to increased colorectal cancer risk in adults in some epidemiological studies.

Key Facts

EPA Maximum Contaminant Level (MCL)	10 mg/L as nitrate-nitrogen (NO3-N)
Is there a safe level?	Below 10 mg/L is considered safe for adults; infants under 6 months should not drink water above this threshold
Primary sources	Agricultural fertilizer and manure runoff; septic system effluent; natural soil deposits
Highest-risk group	Infants under 6 months (methemoglobinemia risk); also pregnant residents and immunocompromised individuals
Does boiling help?	No — boiling concentrates nitrate. Do not boil nitrate-contaminated water for infant use.
Effective treatment	Reverse osmosis (NSF/ANSI 58), distillation, or anion exchange — NOT carbon filters
Private wells	Not regulated under SDWA — owners must test independently. Annual testing is recommended in agricultural areas.
Federal rule	Safe Drinking Water Act — public systems must notify customers within 24 hours of exceeding the MCL

How Nitrate Gets Into Drinking Water

Agricultural fertilizer and manure runoff

Nitrogen-based fertilizers and animal waste applied to cropland can leach through soil into groundwater or run off into surface water supplies — particularly after rain events. This is the dominant pathway in most U.S. regions with elevated nitrate.

Septic system effluent

Failing or poorly sited septic systems can release nitrogen-rich wastewater near drinking water wells. Homes on older septic systems in rural areas, and areas with high well density, face elevated risk.

Concentrated animal feeding operations (CAFOs)

Large livestock operations generate significant quantities of animal waste. Lagoon leaks, overapplication of manure to fields, and proximity to water sources can create localized hotspots of nitrate contamination.

Natural geological deposits

In some regions, naturally occurring nitrogen compounds in soil and rock contribute background levels of nitrate to groundwater. This is less common than agricultural sources but can affect otherwise rural areas.

Who Should Pay Closest Attention

Households with infants under six months

Pregnant residents

Anyone on a private well in an agricultural area

Households near livestock operations or CAFOs

Residents in areas with older or failing septic systems

Rural households on shallow groundwater wells

Critical — Infants Under 6 Months

Do not use water that exceeds 10 mg/L nitrate-nitrogen to prepare infant formula or feed infants under six months. Do not boil this water — boiling concentrates nitrate. Use bottled water, a reverse osmosis system certified to NSF/ANSI 58, or a distillation unit until the issue is resolved. Contact your utility or local health department immediately if you receive a nitrate exceedance notice.

How to Check Your Situation

1
Identify your water utility using the ZIP lookup below or via your state page.
2
Read your utility's page on this site — it shows recent nitrate violations and risk level based on EPA SDWIS data.
3
Review your utility's most recent Consumer Confidence Report (CCR), which must disclose any MCL exceedances in the past year.
4
If you are on a private well, arrange independent testing at a state-certified lab. In agricultural areas, test annually. Your state health department maintains a list of certified labs.
5
If you have an infant under six months, take immediate precautionary steps — use bottled water or a certified RO system — while you gather information.
6
If you receive an official nitrate exceedance notice from your utility, follow their guidance and do not use tap water for infants until the issue is resolved.

Treatment Options

Nitrate is not removed by activated carbon filters, boiling, or UV treatment. Only the options below are effective.

NSF/ANSI Standard 58 — Reverse Osmosis

RO systems certified to NSF/ANSI 58 reduce nitrate by 85–95% at the point of use. Under-sink installation is required. This is the most practical residential option for households with nitrate concerns.

Distillation

Counter-top or under-sink distillation units effectively remove nitrate along with most other contaminants. Produces small quantities of water — suitable for drinking and cooking, not whole-house use.

Anion Exchange

Ion exchange systems designed for nitrate removal use a resin that exchanges nitrate ions for chloride. Effective but requires periodic resin regeneration and monitoring. Most practical as a point-of-entry system.

Carbon filters do NOT remove nitrate

Standard pitcher filters, faucet filters, and activated carbon under-sink filters — including those certified to NSF/ANSI 42 or 53 — are not certified to remove nitrate and should not be used for this purpose.

Utilities With Nitrate Violation Records

Utilities listed below have at least one nitrate violation on record in EPA's SDWIS database. Violations may be open or resolved — see individual utility pages for current status.

Chicago

IL · 2,746,388 served

safe

San Antonio Water System

TX · 2,113,151 served

safe

Philadelphia Water Department

PA · 1,600,000 served

safe

Charlotte Water

NC · 1,163,701 served

safe