If your well water or tap water contains high levels of nitrates or ammonia, it’s not just a taste issue—it’s a health risk. Reverse osmosis (RO) is one of the most effective water purification methods available and can significantly reduce these contaminants. But how well does it really work?
In this article, we break down how nitrates and ammonia get into your water, the health risks they pose, and how RO systems can help. You’ll also find specific RO systems we recommend for removing these nitrogen-based contaminants.
Nitrates Vs Ammonia: What’s the Difference?
Nitrates
Nitrates are inorganic compounds made up of nitrogen and oxygen. They’re naturally present in soil and water, and widely used in fertilizers because they promote plant growth. But while nitrates help crops grow, they can be dangerous in drinking water.
Excessive nitrate levels in water typically come from agricultural runoff, livestock waste, or decomposing plant material. Nitrates are highly soluble in water and can easily seep into groundwater and wells.
Ammonia
Ammonia is a compound of nitrogen and hydrogen. It exists as a gas at room temperature but dissolves easily in water. In water, ammonia often converts to ammonium (NH₄⁺) by reacting with hydrogen from water molecules.
Ammonia is also used in fertilizers and cleaning products. While the human body can process small amounts, high levels in water can be harmful, especially to infants and those with kidney or liver issues.
How Nitrates and Ammonia Enter Drinking Water
Agricultural Runoff & Fertilizers
Rainfall and irrigation can wash fertilizers containing nitrates and ammonia into groundwater and surface water. This is especially common near farmlands.
Animal Waste
Feces and urine from livestock or birds can wash into rivers, dams, and wells. As this organic waste breaks down, it releases both nitrates and ammonia into the water.
Storm Events & First Flush
The first heavy rain after a dry period – known as a “first flush” – can carry large quantities of waste and chemicals into drinking water sources.
Household Wastewater
Cleaning products often contain small amounts of ammonia (e.g., detergents and soaps usually have less than 10%). If not properly treated, wastewater can introduce ammonium into surface water or shallow wells.
Health Risks of Nitrates and Ammonia
Nitrates
Excessive nitrate exposure is especially dangerous for infants and young children. It can lead to methemoglobinemia (“blue baby syndrome”), where red blood cells can’t transport oxygen effectively.
Nitrate contamination has led to major public health alerts. For example, in 2022, residents of Morrow County, Oregon, were issued emergency guidance when domestic wells were found to exceed safe nitrate levels.
Ammonia and Ammonium
The body naturally produces and excretes ammonia as part of digestion, but excess ingestion from water can overwhelm this system. High ammonia levels can irritate mucous membranes and, in large doses, be toxic.
Fortunately, in most water supplies, ammonia converts to ammonium, which is far less toxic and more easily removed by filtration.
How Reverse Osmosis Removes Nitrates and Ammonium
Reverse osmosis systems use a semi-permeable membrane that removes particles based on size. As water is forced through this membrane under pressure, nitrates and ammonium – along with many other contaminants – are rejected and flushed away.
- Nitrate Removal Efficiency: ~89-92%
- Ammonium Removal Efficiency: ~80%
- Ammonia (un-ionized): Not effectively removed without catalytic oxidation, which most home systems don’t offer.
Most household RO systems are effective because ammonia generally converts to ammonium in water.
However, if your nitrate levels are extremely high (above 100-150 mg/L), RO alone may not reduce levels below the EPA’s safe drinking limit of 10 mg/L. In such cases, additional treatment or a whole-house system may be necessary.
NSF Certification for Nitrate Removal
Look for NSF/ANSI Standard 58 certification when selecting a reverse osmosis system. This confirms the unit has been independently tested to remove nitrates, nitrites, and other contaminants. There is currently no NSF standard for ammonia, but RO systems with strong ammonium rejection are still effective.
Best Reverse Osmosis Systems for Nitrate and Ammonium Removal
Crystal Quest 1000M Reverse Osmosis System
- Up to 17 filtration stages
- Optional nitrate-specific cartridge removes 95%+
- Also removes PFAS, chlorine, heavy metals
- Great for well water and high-nitrate areas
Waterdrop G3 Reverse Osmosis System
- Tankless design with smart faucet display
- NSF/ANSI 58 certified
- Removes 93% of nitrates and 80% of ammonium
- Compact and modern—great for small kitchens
Types of Reverse Osmosis Systems That Work
All of these RO systems are capable of removing nitrates and ammonium (though not ammonia in gas form):
- Under-Sink RO Systems – Most common. Easy to use once installed.
- Countertop RO Systems – No installation required. Ideal for renters or small spaces.
- Tankless RO Systems – Space-saving, lower risk of contamination from stagnant water.
- RO Systems with UV Lamps – Combine RO with UV disinfection for added protection.
- Whole-House RO Systems – Best for properties with high nitrate/ammonium levels throughout the home.
Final Note
Reverse osmosis is the best at-home option for removing nitrates and ammonium from drinking water. While it may not eliminate every last molecule of these contaminants, a properly chosen and certified RO system can make your water significantly safer, and in many cases, fully compliant with EPA guidelines.
To remove ammonia from the air in your home, Plentifulair.com has a complete guide available here.