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Disinfection with Chlorine & Chloramine

Below you will find answers to commonly asked questions related to disinfection with chlorine or chloramine.

Frequently Asked Questions

Why do public water suppliers add disinfectants to my drinking water supply?

Water can come from a variety of sources, such as lakes and wells, that can be contaminated with germs which can make people sick. Germs can also contaminate water as it travels through miles of piping to get to a community. To prevent this, water companies add a disinfectant that kills germs. The most commonly added disinfectants are chlorine and monochloramine.

Why is my water provider switching from chlorine to monochloramine disinfection?

The Environmental Protection Agency (EPA) allows drinking water treatment plants to use monochloramine and chlorine to disinfect drinking water 1. Research shows that monochloramine and chlorine both have benefits and drawbacks.

Chlorine is a highly effective method of disinfection. However, it produces small amounts of chemicals (called "disinfection byproducts") while in the pipes. These byproducts can cause illness after drinking them for a long time. Chlorine is also used up quickly in systems. Sometimes there is not enough chlorine left to disinfect the water by the time it reaches the end of the pipes 2.

Monochloramine can last longer in the water pipes and produces fewer byproducts. However, if monochloramine levels get too high, it can result in water pipe damage 3.

To meet the EPA standards intended to reduce disinfection byproducts, some water utilities are switching to monochloramine. Monitoring for the new byproduct standards began in mid-2012 4.

Are there any health issues associated with monochloramine?

Safe drinking water

Current studies indicate that using or drinking water with small amounts of monochloramine does not cause harmful health effects 5. These studies reported no observed health effects from drinking water with monochloramine levels of less than 50 mg/L in drinking water 6. A normal level for drinking water disinfection can range from 1.0 to 4.0 mg/L 7.


When monochloramine reacts with chlorine at a low pH, trichloramine can be produced. Eye and respiratory problems have been linked to trichloramine exposure. If the water in indoor swimming pools and hot tubs is not properly treated, trichloramine may form, and people may experience these health effects. This is particularly true when facilities don't provide enough air circulation to ventilate indoor pools or spas 8.

Dialysis patients

During dialysis, large amounts of water are used to clean waste products out of a patient’s blood. Dialysis centers must treat the water to remove all chemical disinfectants, including chlorine and monochloramine, before the water can be used for dialysis. Home dialysis users should consult the machine manufacturer for instructions on how to properly treat their water before use 2.

Your health

Your water company monitors water quality regularly to provide you safe drinking water.

Some people are more sensitive than others to chemicals and changes in their environment. Individuals who have health concerns should seek medical advice from their physician before contacting their local health department.

Get contact information for your local health department.

Will monochloramine affect my water’s taste or odor?

If you notice any change, it will be that the water treated with monochloramine has less of a chlorine taste and smell than water treated with chlorine 2,3.

Will monochloramine increase the amount of lead or copper in my drinking water?

Monochloramine can change the chemical properties of the water, which can corrode lead and copper pipes 9. Lead and copper levels are strictly regulated in drinking water 10. Your water utility is required to provide high quality drinking water that complies with the Safe Drinking Water Act. [PDF - 4 pages] The EPA provides a manual for water companies switching to monochloramine to minimize lead and copper corrosion 11.

If you are concerned about lead or copper levels in your household water, call EPA’s Safe Drinking Water Hotline at 800-426-4791 for testing information.

Will monochloramine affect my pets or plants?

Chlorine and monochloramine are toxic to fish, other aquatic animals, reptiles and amphibians. Don’t keep these animals in water that contains these disinfectants. Unlike humans and other household pets, these types of animals absorb water directly into the blood stream 12. Chlorine can be removed from water by letting it sit out for a few days. However, monochloramine cannot be removed in this way, so ask your local pet store about methods of removing disinfectants from water for these pets.

The small amount of monochloramine added to water will not affect other pets (such as mammals and birds) and can be used regularly for watering and bathing animals.

Plants are not harmed by water treated with monochloramine.

Is monochloramine treatment new?

Major U.S. cities such as Philadelphia, San Francisco, Tampa Bay, and Washington, D.C. use monochloramine to disinfect drinking water already 3. In 1998, an EPA survey estimated 68 million Americans were drinking water disinfected with monochloramine 10. Monochloramine is recognized as a safe disinfection alternative to chlorine 1,2.

  1. U.S. Environmental Protection Agency. Basic Information about Disinfectants in Drinking Water: Chloramine, Chlorine and Chlorine Dioxide; 2012 Mar 06 [cited 2012 Aug 31].
  2. Water Research Foundation. Water Research Foundation; c 2008-2012. How Chloramines Improve Water Quality. [PDF - 4 pages] [cited 2012 Sept 21]; [page 2].
  3. Water Research Foundation. Long-Term Effects of Disinfection Changes on Water Quality. [PDF - 320 pages] 2007 [cited 2012 Sept 21]; [chapter 3].
  4. U.S. Department of the Interior, Bureau of Reclamation. Disinfectants and Disinfection Byproducts Rules. [PDF - 4 pages] 2008 Sep 30 [cited 2012 Oct 12]; [page 3].
  5. U.S. Environmental Protection Agency. Basic Information about Chloramines. [PDF - 1 page] 2009 Feb 24 [cited 2012 Aug 31].
  6. World Health Organization . Monochloramine in Drinking-water Background Document for Development of WHO Guidelines for Drinking-water Quality. [PDF - 21 pages] 2004 [cited 2012 Sept 7]; [page 9].
  7. U.S. Environmental Protection Agency. Alternative Disinfectants and Oxidants Guidance Manual. [PDF - 346 pages] 1999 April [cited 2012 Sept 21]; [pages 6.1-6.35].
  8. Emanuel BP. The relationship between pool water quality and ventilation The Free Library. 1998;1.
  9. U.S. Environmental Protection Agency. Information about Chloramine in Drinking Water. [PDF - 6 pages] [cited 2012 Aug 23]; [page 3].
  10. U.S. Environmental Protection Agency. Drinking Water Contaminants. 2012 June 5 [cited 2012 August 23].
  11. U.S. Environmental Protection Agency. Simultaneous Compliance Guidance Manual for the Long Term 2 and Stage 2 DBP Rules. [PDF - 462 pages] 2007 March [cited 2012 August 23].
  12. Pinellas County Utilities. Chloramines: Frequently Asked Questions. [cited 2012 Sept 5].

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