Skeptoid PodcastSkeptoid on Facebook   Skeptoid on Twitter   Skeptoid on Stitcher   Skeptoid on Spotify   iTunes   Google Play

Members Portal

Support Us Store


Get a Free Book



MercolaWatch: Overreacting to chloramine in water

by Josh DeWald

December 7, 2012

Share Tweet Reddit

Donate In late November, Joe Mercola posted an article discussing the addition of chloramine in drinking water and its potential effects. Chloramine is a compound sometimes added (going back as far as 1917) as a disinfectant in municipal water supplies during storage and transportation to people's homes. While the EPA considers chloramine to be safe for this use, some people have reported skin irritation and rashes. As with many of his articles, Mercola's tone and content convey significantly more danger than the actual evidence seems to call for. This article will discuss more details from sources he cites, clarify some points as well as present what seems to be the official stance of the EPA on chloramine.

Primary and Secondary Disinfection

Based on EPA regulations, municipal water supplies make use of two complementary phases of disinfection. The first phase is intended to quickly kill most bacteria, viruses, etc as soon as the water comes in from its source. This is usually done using chlorine, but some water systems actually use chloramine in this phase. When water is being stored and transported to people's homes, "secondary" disinfection is required to keep the water clean. This is where chloramine comes in because of its ability to reside longer in the water and so make it all the way to the system end points. Chloramine's ability to form a residual disinfectant in the water is not an undesirable side effect but the reason for it being used in the first place. As the EPA puts it (see Q3 in the "Questions and Answers" document in the references):
Secondary disinfection provides longer-lasting water treatment as the water moves through pipes to consumers.

• Secondary disinfection maintains water quality by killing potentially harmful organisms that may get in water as it moves through pipes

• Monochloramine may be more useful than chlorine in killing certain potentially harmful organisms in pipes such as those that cause Legionnaire's disease.
The usage of chloramine as a disinfectant (primary or secondary) in municipal water supplies is not a new idea that is sneakily being foisted on an unsuspecting public. It has been in long use in America. According to the American Water Works Association, Denver has used chloramine since 1917, Portland 1924, Boston area 1932, etc. While this does not prove that chloramine is safe, it does demonstrate its long use and it stands to reason that it would have become clear if those cities had higher-than-normal cancer and other health effects compared to cities not using chloramine in any capacity. In fact, as Joe Mercola points out, 20% of Americans already have chloraminated tap water. The article implies this is a bad thing, but I would again say that this just means that it has been a part of our water supply for quite a while with no apparent ill effects.

Chloramines May Raise Your Water's Level of Toxic Unregulated Disinfection Byproducts?

If you receive municipal water that is treated with chlorine or chloramines, toxic disinfection byproducts (DBPs) form when these disinfectants react with natural organic matter ... Already, it's known that trihalomethanes (THMs), one of the most common DBPs, are Cancer Group B carcinogens, meaning they've been shown to cause cancer in laboratory animals. They've also been linked to reproductive problems in both animals and humans, such as spontaneous abortion, stillbirths, and congenital malformations, even at lower levels.


In 1998, the U.S. Environmental Protection Agency (EPA) published its Stage 1 Disinfection Byproducts Rule, which required water treatment systems to reduce the formation of DBPs...but what is less publicized is that compared to chlorine, water treated with monochloramine ... may contain higher concentrations of unregulated disinfection byproducts — the risks of which are unknown
I'm not sure it's clear from the quote, but the reason for switching to chloramine from chlorine is to lower the incidence of regulated DBPs in the water.

As far as I can tell, there is no such thing as "Cancer Group B" carcinogens. The closest thing that exists is International Agency for Research on Cancer (IARC) Group 2B, which is for chemicals that are "possibly carcinogenic" to humans (2A is for "probably" and 1 is for "definitely"). The only THM listed in the classification for 2B is Bromodichloromethane (which EPA sets limits for), two of the others are in Group 3 (the same group with caffeine), which means they are "unclassified". To say that THMs as a whole are "Group B" carcinogens seems inaccurate unless there is some other source of "Group B" carcinogens other than the IARC.

Here Mercola links to the answer 23 to one of the EPA's FAQs on chloramine, which does in fact contain essentially that exact text about unregulated byproducts. So first thing to note is that the EPA is not trying to hide this information. The second thing to note is that the EPA also references other questions to get more details (7,9,19). More importantly, they discuss their Unregulated Contaminant Monitoring Rule program (UCMR) in the FAQ, unfortunately with some broken links, but the proper ones can be found here. Every five years they have water systems throughout the country report back on amounts of the unregulated byproducts (in addition to being required to report any findings to customers). While Mercola mentions the 1998, Stage 1 DBP rule, in 2006 the EPA released their Stage 2 DBP rules, which "focuses on public health protection by limiting exposure to DBPs, specifically total trihalomethanes (TTHM) and five haloacetic acids (HAA5), which can form in water through disinfectants used to control microbial pathogens." So the EPA is well aware of trihalomethanes and their potential dangers and is actively monitoring for them. And as the EPA states in the very page (Question 23) that Mercola referenced in his discussion of unregulated DBP,
The EPA believes that water disinfected with monochloramine that meets regulatory standards poses no known or anticipated adverse health effects,including cancer
The point is to kill viruses and other pathogens that we know cause harm. As will many interventions of this sort, it is a matter of risk vs benefit. And this is why the EPA does so closely monitor the levels, set new standards, and continue to research.

Are higher levels of lead linked to chloramine?

While I think that Mercola over-blames chloramine for the increased lead and oversimplifies the cause, I have to concede that the core point he makes in his section on lead is mostly true. It does seem that when switching from chlorine to chloramine (especially long term high levels of chlorine), there is increased risk of lead contamination in homes that contain older lead-containing pipes (generally those built before 1975 and that have not been replaced). I have left the references in place however at the bottom (CDC document on lead and Blood Lead Levels, Question 27 in the "Questions & Answers" from the EPA).

The CDC does point out that any time there are lead pipes, there may still be lead contamination greater than desired lead levels, even with proper corrosion control. Currently utilities only have to replace the lines they own, and offer to replace, but not pay for, lead lines they do not own. The CDC recommends that utilities bear the burden of full replacement of any lead lines.

Are residents voicing concerns over chloramine in the face of weak studies?

In 2007, The Division of Environmental Hazards and Health Effects (EHHE) of the National Center for Environmental Health (NCEH) was asked to investigate complaints of skin irritations and rashes in the Champlain Water District (CWD) of Vermont following the switch from chlorine to chloramine as a secondary disinfectant. A team from the CDC and EPA was sent to handle the investigation. Their report points out the following about local influence (emphasis mine):
...the local chapter of People Concerned about Chloramine (PCAC) had implemented a mass media campaign prior to our arrival...distributed approximately 10,000 flyers by going door to door and approaching individuals "on the street" and in grocery stores. One report stated an individual with visible skin problems was approached by a member of PCAC in the grocery store and was told the source of their skin problem was the chloramine in the tap water...

Field investigators observed PCAC members coaching survey respondents (many of whom are PCAC members) prior to the meeting on Wednesday. In one case, a PCAC member was present during the home visit and prompted the respondent to provide specific answers to our questions.

Based on these influences and biases these results can not be interpreted as representing the rates of symptoms, health conditions, or complaints of the overall community.
So while there were people who reported skin irritation that they believe was caused by chloramine, the report points out that the sampling was very biased, and it seems possible that many of the residents who reported issues were influenced by the PCAC. Reading the notes (which Mercola links to and paraphrases a single line from) of the committee meeting of the group that went to Vermont makes for interesting reading, mostly due to its general tone that the issue of chloramine is more about communication than toxicology. It is mostly a set of Powerpoint slides embedded in the PDF with discussion notes. One slide points out that chloramine is associated with lower bladder cancer versus chlorine, but some evidence of carcinogenity in female rats (but not male rats, and not mice of either gender). They also discuss swimming pool exposure to trichloramines (not monochloramines which are what are used in drinking water).

Mercola again:
...Albemarle County in Central Virginia, which dropped the consideration of chloramines after negative public feedback -- and is now looking at the use of granular-activated carbon as a secondary water disinfectant.
This is true, and the Rivanna Water and Sewer Authority (RWSA) actually has an interesting page with an overview of water treatment, as well as the history of their decision to use chloramine and then switching to granulated-activated carbon (GAC) after public feedback. It should be noted, however, that the decision not to use chloramine was not based on the scientific evidence, but on the public demand. This means that the additional costs of GAC will be passed on to the customers whether or not they take issue with the use of chloramine.

Is chloramine difficult to remove from water?

Chloramine cannot be removed by quick boiling your water or letting it sit out in an open container ... Adding fruit, such as slices of peeled orange, to a 1-gallon water pitcher, which will help neutralize chloramine in about 30 minutes... Dissolving a 1,000-mg vitamin C tablet into your bath water, which will neutralize the chloramine in an average-size bathtub
Vitamin C will indeed neutralize residual chloramine, if you decide it is something you are concerned about. While a "quick boil" won't remove chloramine, a 20 minute gentle boil will, as well as most cooking uses for the water. Additionally any thing that would be used to remove chlorine will also remove chloramine. But again, as the SF Water authority puts it when discussing usage of Vitamin C: "The removal of either chlorine or chloramine from drinking water is not necessary for public health".


Chemicals are always a complex topic to discuss because our human instinct is that we want something that removes all the dangers but is 100% safe (i.e. to "have our cake and eat it to"). It certainly cannot be claimed that the addition of chloramine to drinking water is without any effects. Its purpose is to kill off harmful pathogens, so it certainly could have harmful health effects at high concentrations. But the EPA places strict limits on the amount that can be used as for secondary disinfection purposes and they believe it is safe. Chloramine has been in continuous use for nearly a century in some areas (Denver for example) with no apparent major negative health effects. There are no doubt people who have skin irritation or respiratory effects, the same can be said for nearly any chemical. The benefits for safety seem to provide a good compromise and there are methods to remove residual chloramine once it makes it into the home. It is my view that articles like Mercola's unnecessarily scare people away and could lead to higher cost water for no apparent scientific reason.

1. American Water Works Association. "History of monochloramine use". Visited Dec 3, 2012.
2. Illinois America Water. "Frequently Asked Questions about Chloramination". Visited Dec 3, 2012.
3. US EPA. "Chloramines in Drinking Water". Visited Dec 4, 2012.
4. US EPA. "Chloramine Q&A's". Visited Dec 3, 2012
5. CDC. "Lead in Drinking Water and Human Blood Lead Levels in the United States." Visited Dec 6, 2012
6. IARC. "List of Classifications". Visited Dec 5, 2012
7. US EPA. "Stage 2 DBP Rule". Visited Dec 5, 2012
8. DHS. "Epi-Aid Trip Report: An assessment of health concerns in a community exposedto chloramine treated tap water in Vermont, 2006—2007 (Epi-2007-054)". Visited Dec 6, 2012
9. US EPA. "Unregulated Contaminant Monitoring Program". Visited Dec 4, 2012
11. RWSA. "Drinking Water Disinfectant System Upgrades". Visited Dec 3, 2012.

by Josh DeWald

Share Tweet Reddit

@Skeptoid Media, a 501(c)(3) nonprofit








Want more great stuff like this?

Let us email you a link to each week's new episode. Cancel at any time: