What Is Ammonia in Water and How to Remove It?

Ammonia in drinking water is a topic that comes up in two very different contexts, and understanding which one applies to your situation is the most important step before choosing any treatment approach. The first is ammonia deliberately added to municipal water supplies to form chloramine -- a disinfection practice used in over a third of U.S. municipal water systems.

The second is naturally occurring or contaminant-sourced free ammonia in well water or in water affected by agricultural runoff. Both involve ammonia, but they require different filtration approaches and represent different levels of concern.

What Ammonia Is and Why It Appears in Water

Ammonia (NH₃) is a colorless, highly water-soluble compound of nitrogen and hydrogen. The Water Quality Association notes that it occurs naturally in groundwater at concentrations typically below 0.2 mg/L -- the result of organic material decomposition and microbial processes in soil and rock. At these low natural levels, ammonia in drinking water is not considered a health concern.

The more relevant source for most households on municipal water is intentional addition. For over 70 years, water utilities have added ammonia to chlorine-treated water to form monochloramine, the type of chloramine used in drinking water disinfection.

Chloramine offers utilities two advantages over free chlorine: it produces fewer regulated disinfection byproducts (THMs and HAAs) and it maintains disinfectant residual more effectively throughout the distribution network. The tradeoff for households is that chloramine is approximately ten times harder to remove from water than free chlorine -- and it requires a fundamentally different filtration approach.

The table below summarizes the most common sources of ammonia in household water supplies.

The Chloramine Connection

For the majority of households asking about ammonia in their water, the relevant concern is chloramine rather than free ammonia. If your municipal utility uses chloramination (check your Consumer Confidence Report or call the utility directly), the ammonia is chemically bound to chlorine in a stable compound. This distinction has a direct impact on filtration selection.

Standard activated carbon (GAC) filters are highly effective at removing free chlorine because chlorine reacts readily with the carbon surface. Chloramine is far less reactive -- it passes through standard GAC media without being adequately removed. This is not a filter quality issue; it is a fundamental chemistry difference. The solution is catalytic carbon, which is processed to modify its electronic structure so it can chemically decompose the chloramine molecule rather than simply adsorbing it.

This matters practically for households on chloramine-treated water who assume their existing GAC whole house filter is addressing the disinfection compound in the water. If the system uses standard GAC media, it is not effectively reducing chloramine. Confirming which disinfectant your utility uses -- and choosing the right filter media accordingly -- is the single most important step.

How to Remove Ammonia and Chloramine From Water

The table below summarizes which treatment methods are effective for each form of ammonia.

For households on municipal water that uses chloramine, a catalytic carbon whole house system is the most practical solution. The USWF 2-Stage Chloramine Reduction system uses a Stage 1 sediment pre-filter and a Stage 2 catalytic carbon block specifically engineered to break down monochloramine -- the same system that would be ineffective with standard GAC media. The DFS chloramine reduction systems and filters collection covers whole house and point-of-use catalytic carbon options for chloramine-treated water supplies. For more background on chloramine in drinking water and how it differs from chlorine, the DFS chloramines guide covers the topic in detail.

For households with well water or agricultural runoff concerns where free ammonia is the issue rather than chloramine, reverse osmosis is the most thorough treatment approach. An under-sink RO system removes free ammonia as part of its broad dissolved contaminant reduction, alongside nitrates and other agricultural compounds that frequently co-occur. The DFS reverse osmosis buying guide covers system selection for households dealing with multiple dissolved contaminants from agricultural or groundwater sources.

Before selecting any treatment, a water test kit that includes ammonia and nitrate levels alongside pH and hardness establishes the baseline needed to choose correctly. Well water users near agricultural areas should also test for nitrates, since fertilizer-derived contamination typically introduces nitrogen compounds in multiple forms simultaneously.

For more information on ammonia specifically in the context of drinking water treatment, the DFS ammonia in drinking water guide covers sources, regulated levels, and filtration approaches in additional detail.

Questions about the right filtration approach for ammonia or chloramine in your water? Call the DFS team at 1-800-277-3458.

Frequently Asked Questions

What is ammonia in drinking water and where does it come from?

Ammonia in drinking water comes from several sources. Most commonly, it is added intentionally by municipal water utilities to combine with chlorine and form monochloramine, a disinfectant that provides longer-lasting protection throughout the distribution system.

It also occurs naturally in groundwater at low concentrations from organic decomposition, and can enter well water from agricultural fertilizer runoff or nearby industrial activity.

Is ammonia in tap water harmful?

At the low concentrations used in municipal chloramination (typically under 0.5 mg/L) and at the naturally occurring levels found in most groundwater (under 0.2 mg/L), ammonia in drinking water is not considered harmful to most healthy adults. The CDC notes that current evidence does not show specific health effects from drinking water containing chloramines at regulated levels.

At elevated concentrations, ammonia can cause gastrointestinal irritation. Dialysis patients are a specific exception -- chloramine in water used for dialysis can cause hemolytic anemia and must be removed from dialysis water supplies.

Does a standard carbon filter remove ammonia or chloramine?

Standard activated carbon (GAC) filters do not effectively remove chloramine (bound ammonia and chlorine). They are highly effective for free chlorine but lack the reactivity to decompose the chloramine molecule. Catalytic carbon is the correct filter media for chloramine removal. Standard carbon also has limited effectiveness for free ammonia. Reverse osmosis removes both forms.

How do I know if my water uses chloramine or chlorine?

Check your municipal water utility's annual Consumer Confidence Report, which is required to disclose the disinfection method used. The report is typically available on the utility's website or by calling them directly. Alternatively, a water test kit that measures both free chlorine and total chlorine will confirm chloramination -- if total chlorine is significantly higher than free chlorine, chloramine is present.

What is the best filter for chloramine removal?

Catalytic carbon is the most practical household solution for whole-house chloramine reduction. Catalytic carbon is processed to chemically decompose monochloramine, which passes through standard GAC without being adequately removed.

For point-of-use drinking water, a reverse osmosis system with a catalytic carbon pre-filter provides the most thorough treatment. Standard carbon filters, refrigerator filters, and most pitcher filters are not rated for chloramine removal.

Can reverse osmosis remove ammonia from well water?

Yes. Reverse osmosis membranes remove free ammonia as part of their broad dissolved contaminant reduction, along with nitrates, heavy metals, fluoride, and other dissolved inorganic compounds common in agricultural areas. An under-sink RO system at the kitchen tap is the most thorough point-of-use solution for well water with elevated ammonia or nitrate from fertilizer runoff.

Should I test my water for ammonia?

If your water is on a municipal supply that uses chloramine, confirming this through the utility's Consumer Confidence Report is sufficient -- you do not need to test for ammonia specifically, but you do need to ensure your filtration uses catalytic carbon rather than standard GAC. For well water users near agricultural activity, testing for ammonia and nitrates together provides the complete nitrogen contamination picture needed to select the right treatment.