How to Remove Nitrates from Drinking Water

Health disclaimer: This page provides general information about nitrate treatment options for private well and municipal water. It is not medical advice. If you have an infant under 12 months old or a pregnant person in your home and suspect high nitrate levels, contact a healthcare provider and use bottled water immediately.

Three technologies reliably remove nitrates from drinking water. Carbon filters, softeners, and boiling don’t.

That distinction matters because the wrong product gives you false confidence. Someone who buys a pitcher filter for a nitrate problem is still drinking contaminated water. The same goes for anyone who boils water thinking it helps. Boiling concentrates nitrates by evaporating water while leaving dissolved solids behind. It makes the problem worse.

Here’s how to choose the right treatment for your situation.

What NSF Testing Shows

The NSF certifies filtration products against specific contaminants. For nitrates, three technologies show up in certified test data.

Reverse osmosis systems certified to NSF/ANSI 58 typically achieve 85 to 95 percent nitrate reduction. The membrane rejects dissolved salts, and nitrate is a salt. The exact reduction rate depends on your water pressure, temperature, and membrane age. A well-maintained RO system running at adequate pressure performs at the upper end of that range. An aging membrane or low pressure system performs lower.

Ion exchange, specifically anion exchange resin designed for nitrate removal, can achieve similar reduction rates. This is different from a standard water softener. A water softener uses cation exchange to swap calcium and magnesium for sodium. That does nothing for nitrate. A nitrate-selective anion exchange system uses different resin that targets nitrate specifically.

Distillation removes nitrates by evaporating water and collecting the condensate, leaving dissolved solids, including nitrate, behind. It works. The drawback is practical: home distillation units typically produce one to four gallons per day, which isn’t enough for a household’s full drinking and cooking needs.

Step 1: Know Your Nitrate Level

You need a number from a certified lab before choosing a treatment system.

The reason is practical. If your level is 12 mg/L, just over the EPA limit, a good under-sink RO system handles it easily. If your level is 40 mg/L, you want to confirm your chosen system achieves adequate reduction at that starting concentration and check your membrane more frequently.

A certified lab test for nitrates costs $20 to $50. Your state’s environmental or health department may offer free testing, especially if you’re in an agricultural region where nitrate contamination is documented. Some counties in Iowa, Nebraska, and Kansas, for example, run subsidized testing programs for private well owners.

Home nitrate test strips give rough results but aren’t reliable enough for treatment planning when infant safety is involved. Use a lab.

For lab options, see Best Mail-In Water Tests.

Step 2: Choose Your Treatment Type

The right choice depends on your nitrate level, who’s in your household, and whether you need point-of-use or whole-house treatment.

Under-sink reverse osmosis is the best option for most households. An under-sink RO system treats water at one tap, typically the kitchen sink, and gives you filtered water for drinking and cooking. That covers the exposures that matter most: drinking water, ice, and food preparation.

Under-sink RO systems cost $150 to $400 for the unit. Annual maintenance runs $50 to $120 for filter and membrane replacements. They’re DIY-installable with basic plumbing knowledge, or you can have a plumber do it for $100 to $200.

The key requirement: the system must be certified to NSF/ANSI 58, and nitrate must be listed specifically among its certified reductions. Not all RO systems are certified for nitrate. Check the NSF product database before buying, not the product’s marketing copy.

For vetted RO options, see Best Under-Sink RO Systems.

Nitrate-specific ion exchange makes sense if you need to treat water at every tap, not just the kitchen. A whole-house anion exchange system removes nitrate from all water entering the house. It’s more expensive than point-of-use RO (typically $800 to $2,000 installed) and requires periodic regeneration with salt. But for households that use well water for a large garden, livestock watering, or other purposes where nitrate matters beyond drinking, it addresses the full picture.

This is a different system than a water softener, and the two are often confused. A sales rep who suggests a water softener for nitrate removal is steering you wrong.

Distillation is effective but impractical as a primary treatment for most households. A countertop distiller costs $100 to $300 and produces a gallon in four to six hours. If your household drinks four gallons a day, you’d run the unit continuously. It works better as a backup or for single-person households with low daily demand.

What doesn’t work: carbon block filters, pitcher filters (Brita, ZeroWater, Clearly Filtered), refrigerator filters, standard water softeners, and UV systems. None of these remove nitrate. UV disinfection treats microorganisms only. Carbon filters address taste, chlorine, and some organic chemicals. They don’t touch dissolved salts like nitrate.

And again: never boil water to treat nitrate. It concentrates what you’re trying to remove.

Step 3: Verify the Certification

This is where people make mistakes. They buy an RO system, assume it handles nitrate, and never check.

The NSF maintains a searchable product database at nsf.org/certified-products. Search by brand name and model number. Confirm two things: the system is certified to NSF/ANSI 58, and nitrate is listed among the certified contaminant reductions.

Some RO systems are certified to NSF 58 for other contaminants but haven’t been tested specifically for nitrate reduction. Those gaps show up in the database. Don’t assume. Check the actual certificate.

If you can’t find a system in the NSF database, look for the Water Quality Association (WQA) Gold Seal as an alternative certification, using the same standard.

Step 4: Set Up and Monitor

Install the system according to the manufacturer’s instructions. For under-sink RO, installation typically involves connecting to the cold water line under the sink, mounting a small storage tank, and running a dedicated dispensing line to a separate faucet.

After installation, flush the system by running the dispenser until the tank empties twice. The first cycles may taste slightly different as manufacturing residues clear.

A TDS (total dissolved solids) meter gives you a simple way to monitor membrane performance over time. Fill the meter from your tap, then from your RO dispenser. A healthy RO system typically reduces TDS by 90% or more. As the membrane ages, that gap closes. If you’re seeing 60% or less reduction, it’s time to replace the membrane.

Retest your well water every year. Your nitrate level can change with rainfall patterns, nearby land use, or seasonal fluctuations. An annual lab test tells you whether your treatment system is keeping up with what’s coming out of the ground.

For context on where your nitrate is coming from, see Nitrates in Well Water: Agricultural Sources.

For the full nitrate overview including the infant emergency risk, EPA limits, and geographic hotspots, see nitrates in well water.

Sources:

• EPA National Primary Drinking Water Regulations, Nitrates: https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations
• NSF/ANSI Standard 58: Reverse Osmosis Drinking Water Treatment Systems
• PMC, Blue Baby Syndrome and Nitrate-Contaminated Well Water: https://pmc.ncbi.nlm.nih.gov/articles/PMC1638204/

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Health disclaimer: WaterAnswer.com provides general information only. If you have concerns about nitrate exposure for infants, pregnant individuals, or anyone with a health condition, contact a healthcare provider. For emergencies, call 911.