Questions and Answers about Monochloramine

Monochloramine Basics

What is monochloramine (chloramine)?

Monochloramine is a chemical disinfectant used to treat drinking water. It is formed by mixing chlorine with ammonia. Although monochloramine is a weaker disinfectant than chlorine, it is more stable and extends disinfectant benefits throughout a water utility’s distribution system (a system of tanks and pipes used to deliver water to homes). Monochloramine also creates fewer of the regulated harmful disinfection byproducts than chlorine.

How is monochloramine used?

Public drinking water utilities are required by the U.S. Environmental Protection Agency (EPA) to use a primary disinfectant (at the water treatment plant) to inactivate pathogenic organisms remaining after filtration. Drinking water treatment facilities generally choose between chlorine, chlorine dioxide, ozone, chloramines or combination systems (UV light) dependant on their size and initial water quality.

Some water systems use monochloramine instead of chlorine for secondary or residual disinfection (disinfection of the water after it leaves the treatment plant and as it travels through the distribution system to the customer’s tap). Monochloramine use is closely regulated by EPA.

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Is monochloraminated water safe to use and to drink?

Monochloramine (and chlorine) is quickly broken down by the digestive system, and it is not stored up in the body. Water treated with monochloramine at levels below the EPA standard (4.0 mg/L) is considered safe for drinking and all other general household uses — such as bathing, cooking, laundry and cleaning. The water is considered safe for everyone, including babies, children, pregnant women, the elderly and the ill. The water is also safe for pets (EXCEPT fish, amphibians, reptiles and turtles) and safe for plants. It can be used for gardening and watering lawns.

Are there any health cautions related to monochloramine?

Like chlorine, water containing high concentrations of monochloramine can be toxic, especially to sensitive individuals. Some people who use water containing monochloramine above the 4.0 mg/L may experience irritation to their eyes and nose. Some people who drink water containing monochloramine above the 4.0 mg/L could experience stomach discomfort or anemia. See Health Questions.

What effect does monochloramine have on kidney dialysis?

Like chlorine, monochloramine must be completely removed from water before it is used in kidney dialysis machines. If monochloramine or chlorine enters the bloodstream directly, without being broken down by the digestive system, it will harm the patient’s health. Patients who require kidney dialysis can safely drink, cook with, bathe or shower in water treated with monochloramine.

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Is monochloramine new?

No. Monochloramine has been used to disinfect drinking water in the United State since the early 1900s.

How many people are using drinking water that has been treated with monochloramine?

EPA estimates the number exceeds the 68 million people who were identified in a 1998 survey.

How widespread is the use of monochloramine?

Many cities in the U.S. and Canada have used monochloramine as a drinking water disinfectant for decades. Monochloramine is currently used in San Francisco, Houston, Dallas, Denver, Tampa and Boston. Most major water utilities in California use monochloramine. In 1996, approximately 6.9 million Canadians were served by monochloraminated drinking water.

Monochloramine is also used in Australia, England, and Finland. In New England, more than 3 million people in 135 communities are served by water treated by monochloramine.

The EPA estimates that nationally, approximately 60 percent of surface water utilities will use monochloramine for secondary disinfection to comply with more stringent regulatory requirements by 2012.

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Have any water utilities stopped the use of monochloramine?

Hundreds of utilities have switched to monochloramine for secondary disinfection, but the Vermont Department of Health is not aware of any municipalities that have switched back from monochloramine for secondary disinfection to a strictly chlorine-based system. Some utilities in warmer climates, as part of their normal operating procedure, will perform a temporary super-chlorination (or shock) of their water systems to wash out any residue or biofilm, before going back to monochlorimination for secondary disinfection.

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Drinking Water Disinfection

Why are public water supplies disinfected?

Water drawn from surface water sources (lakes or ponds) must be disinfected to kill bacteria, viruses and other organisms that can cause serious illness and death. Primary disinfection at the treatment plant is required by law under the EPA Surface Water Treatment Rule. In Vermont all systems use chlorine primary disinfection. A secondary disinfectant (chlorine, monochloramine or chlorine dioxide) is also required to treat any type of contamination that could occur after the water leaves the treatment plant.

Due to drinking water disinfection, there are no outbreaks of cholera, typhus, or other waterborne diseases that kill over 10 million people each year in places where drinking water supplies are not disinfected.

What disinfectants are there?

There are a number of disinfectants that are effective at killing disease-causing microorganisms, including chlorine, chloramine, ozone, chlorine dioxide and ultraviolet (UV) light. A residual amount of disinfection has to be maintained throughout the distribution system to keep water safe as it moves to the consumer’s tap. Ozone, chlorine dioxide and UV light, which are alternatives to chlorine, are very effective treatment facility disinfectants to ensure public health protection. However, ozone or UV light cannot provide a continuous residual in the distribution system. Chlorine dioxide, while it can maintain a residual, presents operational difficulties. Therefore, water utilities typically use either chlorine or monochloramine as residual (secondary) disinfectant for the distribution system.

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Does EPA require systems to use monochloramine?

The EPA has no requirements that any system use monochloramine for water treatment. However, it has been used by water systems for about 90 years and its use is closely regulated. It is almost always used as a secondary disinfectant, and not as a primary disinfectant.

What is EPA’s standard for monochloramine in drinking water?

The EPA has a regulatory standard and a health goal for disinfectants. The enforceable standard is the highest level of a disinfectant that is allowed in drinking water. The health goal is the level of a drinking water disinfectant, below which there is no known or expected risk to health. The EPA sets the standard as close to the health goal as feasible.

In the case of monochloramine, the standard and the health goal are the same (4.0 milligrams per liter (mg/L) or 4.0 parts per million (ppm) measured as chlorine as an annual average). This is the standard set for a drinking water disinfectant with no known or expected risk to health. This is the maximum allowed. In practice, most systems use half this amount.

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What are the advantages of using monochloramine?

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Does the use of monochloramine affect lead and copper corrosion?

Use of chloramine can indirectly affect corrosion of lead and copper in two ways:

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Monochloramine Use in Vermont

Where is monochloramine used in Vermont?

The only public water system in Vermont that uses monochloramine at this time is the Champlain Water District (CWD). CWD switched from chlorine to monochloramine for secondary disinfection of its water supply in April 2006. CWD serves nearly 68,000 people in 12 Chittenden County municipalities.

Municipalities served by the Champlain Water District:

Burlington is not part of the CWD system and does not use monochloramine.

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Why did the Champlain Water District switch to monochloramine?

The Champlain Water District switched to monochloramine to reduce regulated disinfection products and maintain a disinfectant residual within the distribution system. Monochloramine disinfection is one way to comply with new and stricter standards under the EPA's Safe Drinking Water Act. Use of monochloramine reduces the production of harmful disinfection byproducts such as trihalomethanes (THMs) and haloacetic acids (HAAs), which result from the combination of free chlorine with organic material found in surface water.

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Health Questions

Is monochloraminated water safe to use?

Water treated with monochloramine that meets the EPA standard (4.0 mg/L) is considered safe for drinking and all other general household uses such as bathing, cooking, laundry and cleaning. The water is safe for everyone, including babies, children, pregnant women, the elderly and the ill. Monochloramine (and chlorine) is quickly broken down by the digestive system, and it is not stored up in the body.

The water is also safe for pets (EXCEPT fish, amphibians, reptiles and turtles) and safe for plants. It can be used for gardening and watering lawns.

Are there any health cautions related to monochloramine?

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Are there symptoms of adverse health effects associated with monochloraminated water?

There are no symptoms that have been associated with monochloramine at levels used to treat water. The Vermont Department of Health has searched for and reviewed all available research, and consulted with CDC and EPA. To date, the Health Department has found no credible evidence to show that the use of monochloramine to disinfect public drinking water is a threat to public health, or has been associated with adverse health effects.

However, it is possible that sensitive individuals have symptoms that have not been diagnosed or treated, and it is possible that these are related to monochloramine. If you have a medical or health problem, it is always important that you check with your health care provider for appropriate diagnosis and treatment.

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If I am experiencing respiratory, skin or digestive problems. Could it be related to monochloramine?

All available studies do not link these conditions to monochloramine or chlorine at the level the public is exposed to in drinking water. EPA has set what it believes is a safe limit to exposure to monochloramine in the drinking water, and this limit is closely monitored by the water system. There are many different causes of irritation, and the source is difficult to identify and varies with each person. If you have a health or medical concern, consult your health care provider.

Is monochloraminated water safe to drink?

Yes. Monochloraminated water is considered safe for everyday household uses, including drinking. Monochloramine (and chlorine) is quickly broken down and neutralized by the digestive system. It is not stored up in the body. Anyone can drink water that contains monochloramine at levels regulated by the EPA. This includes babies, children, pregnant women, the elderly, kidney dialysis patients and people with chronic illness.

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Does monochloramine cause skin or digestive problems?

There is no evidence that links these conditions to monochloramine or chlorine at the level the public is exposed to in drinking water regulated by the EPA.

Does monochloramine cause rashes?

Skin rashes have not been associated with exposure to monochloramine.

Does monochloramine cause asthma?

No studies have demonstrated an association between exposure to monochloramine in public water supplies and asthma or worsening asthma symptoms.

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Has monochloraminated water been linked to any common health conditions — such as hair loss, weight loss, depression or oral lesions?

No. After nearly 90 years of use as a secondary disinfectant, there is no evidence in medical literature reviewed by the Department of Health that links monochloraminated drinking or bathing water to any of these conditions.

Can you safely wash an open wound with monochloraminated water?

Yes. It is safe to use monochloraminated water in cleaning an open wound because virtually no water enters the bloodstream in this way.

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Why is monochloraminated water a concern for kidney dialysis patients?

Monochloramine must be removed from the water used in kidney dialysis machines. Dialysis systems already pre-treat their source water to remove chlorine. Some modifications are necessary to remove the monochloramine. Home dialysis service companies can usually make the needed modifications.

Medical facilities in Vermont that perform kidney dialysis were notified by CWD of this change to monochloraminated water treatment before its switchover in 2004.

Kidney dialysis patients can safely drink, cook, and bathe with monochloraminated water.

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Why does the Centers for Disease Control and Prevention (CDC) recommend that people with compromised immune systems boil their drinking water?

Neither chlorine, nor monochloramine, can destroy certain protozoans like Cryptosporidium if filtration is unable to remove them. Some people who have compromised immune systems may wish to use bottled water or to boil their water to make sure they are not exposed to pathogens that may be present in the water despite the use of disinfectants.

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Fish, Pets, Pools

Is monochloraminated water harmful to fish? reptiles? turtles? amphibians?

Monochloramine (and chlorine) is toxic to fish, reptiles that live in water, turtles and amphibians at levels used for drinking water. Unlike chlorine, monochloramine does not quickly evaporate on standing or by boiling. Therefore, fish owners must neutralize or remove monochloramine from water used in aquariums or ponds. Treatment products are readily available at stores where you buy aquarium supplies.

Can pets, birds or wildlife safely drink or bathe in the water?

There is no reason to believe that monochloramine at levels used for drinking water is unsafe for other pets, birds or wildlife.

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Can you safely water grass, plants, vegetables or fruit?

Yes. The small amount of monochloramine in the water supply will have no effect on plants of any type. You can use the water for gardening, washing food and watering lawns.

Will monochloramine affect your swimming pool or hot tub?

No. You will still need a free chlorine residual to retard algae and bacteria growth. Contact your local pool supply stores for specific information.

The Centers for Disease Control & Prevention (CDC) has warned about health effects from high levels of trichloramine in swimming pools. Trichloramine is formed when the chlorine in a swimming pool reacts with nitrogen from sweat and urine. Trichloramine is not the same as monochloramine, it has a different chemical composition. The CDC warning does NOT apply to monochloramine at levels found in the water supply.

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Home Water Treatment Devices

Will monochloramine dissipate or evaporate out of the water?

No. Boiling the water or letting it sit out in an open container at room temperature will not get rid of monochloramine.

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Are there home devices that can be used to remove monochloramine?

Boiling the water or letting it sit out in an open container at room temperature will not get rid of monochloramine. There are "Point of Entry" and "Point of Use" (POE/POU) devices that can be used to remove monochloramine from household water.

NSF International (National Sanitation Foundation) is a not-for-profit / non-governmental organization that provides independent third-party verification testing of home water treatment devices for the removal of monochloramine. Neither the State of Vermont nor the EPA tests or approves home treatment devices.

Drinking water treatment devices are certified to improve water for aesthetic (taste or odor) reasons, and certified devices must demonstrate at least an 83% monochloramine reduction (at 3 ppm) over the entire service cycle of the filter media. All of the devices certified for monochloramine reduction treat the water using adsorption methods (i.e. granular activated carbon).

The majority of the certified products are point-of-use devices.
Point-of-use devices are primarily used for treating drinking water and may be plumbed in to an existing tap, plumbed into a new tap, or placed on a counter top and connected to an existing faucet. These devices are typically intended for cold water use only. There are over 100 certified point-of-use devices for monochloramine, and prices range from less than $100 to $700+. Generally, the flow rates of the devices are too small for whole-house treatment or shower use.

NSF International’s web site lists two point-of-entry products certified for monochloramine removal.
Point-of-entry devices may treat all incoming water to a house and are typically intended for cold water use only. The two products listed on NSF International’s web site are in the price range of $1,300, and are rated for 5 gallons-per-minute flow. This flow rate should be adequate for typical household water use.

Proper installation and maintenance is essential.
The homeowner is responsible for servicing water treatment devices in their home at regular intervals as specified by the manufacturer. For the monochloramine-certified devices, this typically involves replacing the absorption media (the filter) at the end of the service cycle. Improper maintenance will reduce the removal effectiveness of the device and may create a health risk by allowing bacteria to grow in the filter. The cost of regular service and replacement filter media should be considered when deciding on a home treatment device.

The length of the service cycle varies by product.
For the point-of-use devices, the range varies widely, from 300 to 60,000 gallons. The two point-of-entry devices have a service cycle of 21,000 gallons and 84,000 gallons, which corresponds to approximately 2.5 months or 9.5 months for the typical water use of a family of four.

NSF does not certify shower head devices for monochloramine reduction. Some devices are available that claim to reduce monochloramines in shower water.
Shower head devices that add ascorbic acid (Vitamin C) to the water claim to reduce monochloramine concentrations. The use of ascorbic acid to reduce chlorine and monochloramine concentrations is an established practice in the water industry when necessary to dechlorinate wastewater that will be discharged to surface water. Ascorbic acid works by chemically reducing monochloramine in water to chloride, ammonium, and dehydroascorbic acid. To EPA’s knowledge, the performance of these shower head devices has not been tested through third party verification.

To obtain a list of NSF Certified Drinking Water Treatment Units:

Source: US Environmental Protection Agency

Home filters not NSF certified that are charcoal filters can be checked to demonstrate their ability to remove monochloramines. One would need a home test kit to measure total chlorine. Test kits are available from HACH Company, which manufactures and distributes analytical instruments and reagents used to test the quality of water.

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