How to Remove Nitrates from Water

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If you own a private well and you live in a rural area, there’s a good chance that your water contains traces of nitrates.

We’ve poured hundreds of hours into testing and reviewing the best well water filtration methods, and we’ve used our own experience, alongside industry data, to share this guide to the most effective methods for removing water nitrates.

📌 Key Takeaways

  • The best ways to remove nitrates from water are with anion exchange filters, reverse osmosis systems, and water distillers.
  • Boiling water or using a KDF, ceramic, or ultrafiltration water filter is NOT an effective way to remove fluoride.
MethodEffectiveness (Nitrate Removal)AdvantagesDisadvantages
Reverse OsmosisUp to 99.99%Highly effective, removes many contaminantsExpensive, high water pressure required, produces wastewater
DistillationUp to 99.9%Highly effective, removes many contaminantsSlow, energy-intensive, limited water production
Ion ExchangeUp to 90%Moderate efficiency, good for other contaminantsRequires maintenance, not effective for high contaminant levels
Activated Carbon50-80%Cost-effective, simple to use, versatileLower efficiency, frequent replacement needed
Catalytic CarbonUp to 90%Higher efficiency than regular carbon, longer lifespanMore expensive, sensitive to water conditions
Activated AluminaUp to 80%Affordable, reusable, effective for many contaminantsLower efficiency than some methods, sensitive to competing ions
water treatment methods for nitrate removal infographic

📥 Reverse Osmosis

Reverse osmosis water treatment can effectively eliminate more than 99.9% of all total dissolved solids, including nitrates.

How it Works

A reverse osmosis filtration system is typically installed at a specific point of use in your home and consists of several filters, including a sediment filter, a carbon filter, and a effective semi-permeable membrane.

Reverse osmosis systems force water through their filters and membrane at a high pressure. The filters trap specific contaminants, such as sediment and chlorine, but the RO membrane is responsible for the reduction of nitrates.

It has tiny pores that only allow water particles to pass through, while nitrates, nitrites, and hundreds of other contaminants are expelled from the system with the reject water.

Reverse osmosis filtration can help to greatly reduce nitrates, but it won’t eliminate them. Also Keep in mind that RO does produce some wastewater.

The Evidence

Reverse osmosis system example

Best For

Folks who want to remove as many contaminants as possible from their water, including high nitrate concentrations.

⚗️ Distillation

A water distiller is another effective solution for reducing the nitrate concentration in your drinking water.

How it Works

Distillation works by heating water until it boils and evaporates, leaving behind the impurities that are unable to convert into a gaseous state.

The evaporated water then travels out of the boiling chamber and condenses into a liquid state in a separate container.

Water distillers don’t only get rid of nitrite and nitrate – they can also eliminate most other impurities, including illness-causing bacteria, chemicals, and heavy metals like lead.

The only real setback of a distillation system is that it’s a very lengthy process, taking up to 6 hours to provide a single 1-gallon batch.

The Evidence

Water distiller

Best For

Anyone who prefers a non-RO method of greatly reducing their water’s nitrate levels and virtually all other impurities, without the maintenance requirements of a conventional water filtration system.

🔀 Anion Exchange

Ion exchange technology removes nitrates through an ion exchange process.

How it Works

In an anion exchange system, resin beads with positively charged ions (usually chloride) attract and exchange places with the negatively charged nitrate ions present in the water.

As the water passes through the resin bed, the nitrate ions are captured by the resin, and chloride or similar negatively charged ions are released into the water to balance out its charge.

The most effective ion exchange occurs when there are low levels of sulfate ions in the water water.

Anion exchange resins attract both sulfate and nitrate, favoring sulfate, which means if the water has high sulfate levels, you may not benefit from complete nitrate removal.

The resin bed needs to be regularly regenerated to remove the accumulated nitrate ions and replenish the chloride ions.

Anions and cations explained

The Evidence

Best For

People who specifically want to target nitrates in their water supply with a capable resin-based water treatment system that doesn’t require frequent filter replacements.

🔮 Activated Carbon Filters

We’ve read conflicting information about activated carbon’s ability to remove nitrates, with some sources saying it’s capable of this, and others saying it’s not.

But we have been able to find studies that prove activated carbon is capable of removing nitrates to some extent, so we wanted to list it in this guide.

How it Works

Activated carbon filters grab contaminants and pull them out of water, in a process known as adsorption.

These filters may be used in standalone filter systems, like water filter pitchers and faucet filters.

They’re also used in multi-stage systems, like reverse osmosis systems, under-sink filtration systems, and whole-house systems.

Activated carbon block filters

The Evidence

  • One Romanian study found that GAC adsorbents had “excellent capacities of removing nitrate” from groundwater sources.
  • Another study conducted in 2015 analyzed the nitrate removal efficacy of activated carbon prepared from rice husk, and found that the maximum removal of nitrate with this media was 93.5%.

If you’re interested in an activated carbon filter, our tip is to check to see if the filter has been tested or certified for nitrate removal, which should reassure you of its capabilities.

Best For

Folks who prefer a traditional water filtration system that can enhance their water quality and taste as well as reducing contaminants with health risks, like nitrates.

🚰 Catalytic Carbon Filters

Catalytic carbon is a type of activated carbon media that has been enhanced, making it capable of removing additional contaminants.

How it Works

Catalytic carbon works in the same way as activated carbon: it adsorbs contaminants in a drinking water supply, preventing them from leaving the filter with the water molecules.

Catalytic carbon filters are most commonly found in multi-stage water filtration systems, including whole-house water filter systems and under-sink systems.

Because catalytic carbon has a higher reactor efficiency, the media provides more opportunity for nitrate removal compared to normal activated carbon.

Catalytic carbon

The Evidence

  • One 2022 study found that an activated carbon could remove 97.12% of nitrates – up from 55.15% – when a catalyst was added inside the membrane, converting it to catalytic carbon.

There haven’t been as many studies that specifically look at catalytic carbon for nitrate reduction. So, again, make sure your catalytic carbon filter of choice offers a performance that’s backed by laboratory testing, and check that it has been tested to remove more than 90% of nitrate before you spend your money.

Best For

Anyone who wants a superior alternative to normal activated carbon that has enhanced contaminant removal abilities, including the ability to adsorb more nitrates.

🪩 Activated Alumina Filters

We also found several studies that support the nitrate reducing capabilities of activated alumina water filters.

Activated alumina is predominantly favored for its ability to reduce fluoride and arsenic, two contaminants that are notoriously difficult to remove with traditional filtration methods.

But this water filter media has also proven effective at reducing nitrate by at least 80%.

How it Works

Activated alumina water filters work by adsorbing contaminants on a bed of activated alumina granules. The contaminants are trapped in the filter media, reducing their concentrations in the filtered water.

From what we can tell, however, activated alumina only appears to be very effective at removing nitrates when there’s a long contact time between the contaminated water and the media. That may mean that, in certain applications, activated alumina can’t be used for nitrate reduction.

Activated alumina
Source: GOKLuLe 盧樂, CC BY-SA 3.0, via Wikimedia Commons

The Evidence

  • A study conducted in 2020 found that activated alumina could reduce at least 83% of nitrate, and the efficacy of removal rose to 93% with a lower pH of 4. However, these results were achieved when water had an extended contact time with the filter media (at least 30 minutes).
  • A 2017 study concluded that activated alumina “has a good effect on nitrate removal”, and that increasing the alumina content and the number of filter pores increased the number of active adsorbent sites, further enhancing the filter’s nitrate removal abilities.

Best For

People who want to reduce several difficult-to-remove contaminants, such as fluoride and arsenic, alongside nitrate. Note: be sure to check that an activated alumina filter has been tested to remove nitrate before you spend your money.

⚠️ Which Water Treatment Methods Are Not Effective for Nitrate Removal?

There are a number of water treatment methods that aren’t usually capable of removing nitrates:

KDF Filters

We’ve read a bit of misinformation online that says KDF can remove nitrates, but as far as our research tells us, KDF media should not be relied upon for nitrate removal.

Ceramic Filters

Again, based on our research, ceramic filters alone can’t be used to remove nitrate. These filters would need a filter core, such as certain types of activated carbon, that has nitrate removal abilities.

Holding ceramic water filter

Ultrafiltration Filters

Ultrafiltration is similar to reverse osmosis, with a membrane that removes most contaminants, However, the UF pore size is too large for effective nitrate reduction – 0.02 to 0.05 microns (reverse osmosis membrane pores are much smaller, at around 0.0001 microns).

Water Softeners

Some people wrongly assume that water softeners are capable of nitrate reduction because they use ion exchange. It is true that ion exchange technology is capable of removing nitrates, but only one specific type of ion exchange: anion exchange. Cation exchange (the process used in water softeners) can’t reduce nitrates at all.

❔ Frequently Asked Questions

How can I prevent nitrates from getting into my well water?

Unfortunately, if you live in a region where nitrates are a known problem in the groundwater, you won’t be able to completely prevent exposure to these in your well. However, there are several ways that you can at least protect the area around your well from contamination. If you have an old well, make sure the casings are watertight and aren’t damaged, since this could provide a route for nitrates to feed into your water. If you are building a new well, make sure it isn’t shallow – shallow wells are more vulnerable to nitrate contamination. The EPA recommends testing your well for nitrate contamination routinely.

Continue Reading: Our guide to testing for nitrate contamination

Can a water softener remove nitrates?

No, conventional salt-based softener systems with a brine tank can’t provide nitrate or nitrite removal. Only a specific type of ion exchange can remove nitrates. Cation exchange (the type of resin used in water softeners) can’t remove nitrates, but anion exchange resin can.

Does boiling water remove nitrates? 

No. Boiling water only causes some of the water to evaporate, while the same concentration of nitrates remains. The only way to remove nitrates from water is with a physical filtration method.

How do you remove nitrates from water naturally?

There’s no 100% natural way to remove nitrates from water. However, if you want to use a process that’s as natural as possible, use a water distiller. Water distillers vaporize and condense water, and most impurities (including nitrates) are left behind in the boiling chamber due to a difference in their boiling points. The process of distillation simply involves heating and cooling water, and no chemicals, additives, or other artificial methods of water treatment are used.

What kills nitrates in drinking water?

Nothing can be used to kill nitrates in drinking water because they’re not alive. The reason why microorganisms can be killed in water is that they’re living organisms. Nitrates, on the other hand, are dissolved ionic compounds many of which come from chemical pesticides and herbicides, so they can only be physically filtered out of water.

  • Michael Claybourn
    Water Treatment Specialist

    With 25+ years in water treatment, Michael Claybourn Sr. (WT Specialist 3) leads his company, Water of Texas LLC, in solving industrial, commercial, and residential water challenges. From filtration to ozone, he tackles any task, from initial consultation to equipment maintenance. His passion, honed in nuclear power and Culligan of Brazosport, fuels his commitment to delivering pure, healthy water for every client.

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