High nitrate levels in drinking water may impact health, especially in babies under six months. However, nitrate exposure is rarely an immediate health concern for others — with potential exceptions for those with certain conditions and women who are or may become pregnant. However, long-term exposure should be minimized to avoid negative health impacts.
Nitrite, however, can be harmful at lower amounts. It directly interferes with the blood’s ability to carry oxygen, which means infants and other vulnerable groups can be at risk of methemoglobinemia (also known as “blue baby syndrome”) even when nitrite concentrations are much lower than nitrate.
Because nitrate and nitrite are both colorless, tasteless and odorless, water testing is the only way to know if they’re present in your drinking water. Here’s your guide to nitrate and nitrite in drinking water—how they get there, why they matter and how to protect your household.
How to Handle Nitrate and Nitrite in Water
If you suspect that your water may contain high levels of nitrate or nitrite, the first step is to have a professional water test. Laboratory-certified testing is the most accurate method. If your test shows nitrate or nitrite contamination, it is also recommended to then test for coliform bacteria. This is because nitrate and nitrite frequently come from human or animal waste (septic systems, manure, sewage leaks) or organic matter breakdown. These same sources can also introduce bacteria and pathogens into groundwater, including total coliforms and E. coli.
From there, your water expert will help you find the right solution. The best option for nitrate and nitrite reduction is a reverse osmosis (RO) water filtration system that is certified specifically to address these contaminants. With this approach, you can also get protection against a broad array of other potential contaminants in your water as well as better taste, smell and appearance.
Note that not all RO systems are certified for this purpose, and that activated carbon filters, like those in many fridge and pitcher filters, do not remove nitrate or nitrite. Culligan’s Aquasential® Reverse Osmosis System and Aquasential® Smart Reverse Osmosis Nitrate System certified to reduce both nitrate and nitrite, along with more than 90 other potential contaminants.
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Does Boiling Water Remove Nitrate or Nitrite?
It’s important to note that boiling water does not remove nitrate or nitrite. In fact, boiling can increase the concentration of these contaminants by evaporating water and leaving more nitrate and nitrite behind.
If you have high levels of either compound, it’s best to use an alternate water source until you can install a certified treatment system.
The Science of Nitrate and Nitrite in Drinking Water
Looking to know more about nitrate and nitrite and how they could end up in your water? You’ve come to the right place.
What are Nitrate and Nitrite?
Both nitrate (NO₃⁻) and nitrite (NO₂⁻) are forms of nitrogen. They are part of the natural nitrogen cycle but also have significant man-made sources.
- Nitrate is more stable and common in water supplies. It is often found in fertilizers, animal manure and decaying organic matter.
- Nitrite is an intermediate form produced when bacteria convert ammonia into nitrate. It is usually short-lived in oxygen-rich environments, but it can show up in recently contaminated or inadequately disinfected water.
How Do Nitrate and Nitrite Get into the Water Supply?
When rain or snowmelt moves through soil and rock, it can carry nitrogen compounds into groundwater and surface water. Sources include:
- Agricultural runoff: Fertilizer and manure applied to fields can leach into groundwater.
- Septic systems and wastewater: Improperly managed waste can release ammonia, which bacteria convert to nitrite and nitrate.
- Landfills and industrial sites: Organic waste and chemicals can contribute to nitrogen contamination.
Because around 145 million Americans and 12.5 million Canadians rely on groundwater for drinking, cleaning and bathing, it’s possible for nitrate and nitrite to be part of everyday life. While nitrate is the more common form, nitrite may also appear in certain situations:
- Shallow or recently contaminated wells, especially after heavy rain
- Water systems affected by sewage, septic or manure runoff
- Environments with low oxygen (such as near landfills or stagnant groundwater), where full conversion to nitrate doesn’t happen
Are There Safe Levels?
Yes — within limits. Both the U.S. Environmental Protection Agency (EPA) and Canadian Guidelines for Drinking Water Quality have set maximum contaminant levels (MCLs): for nitrate, it’s 10 mg/L and for nitrite, it’s 1 mg/L.
Public water systems must meet these standards. However, private well owners are responsible for their own testing and treatment — and wells, especially shallow rural ones, are most at risk of contamination.
Who Is Most Susceptible Health Risks?
Infants are perhaps the most vulnerable when it comes to high nitrate levels. That’s because nitrate reduces the blood’s ability to carry oxygen — and while adult blood cells can recover quickly, the same isn’t true for babies.
Pregnancy also increases oxygen demand, making nitrate/nitrite exposure riskier for pregnant individuals.
Other health conditions bring increased risk, as well: Adults with anemia, lung disease, low stomach acid, cardiovascular disease or genetic conditions may be more sensitive.
Managing Nitrate and Nitrite in the Water Supply
Municipal water systems regularly test for nitrate and nitrite, notifying communities if levels are elevated. For private well owners, annual testing is strongly recommended — particularly in agricultural or rural areas.
Even if no one in your household is especially vulnerable, it’s smart to understand what’s in your water. That way, you’re always in control of what you drink — and what you provide for your family, guests, and pets.
A professional water test is the first step. After that, water experts can help you choose the right system to reduce nitrate and nitrite, along with many other contaminants, so you can enjoy safe, great-tasting water every day.
Take the first step toward better water by scheduling your in-home water test and consultation today.
