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Most people are very familiar with their home water taste. So familiar that they cannot taste it and only notice the difference in other water sources. Descriptions like “irony” or “chemically” or “smelly” often get thrown around in water taste tests. Thankfully, most homes are very lucky to have clean water flow directly to them, usually without thinking twice about it. Many factors contribute to water quality and composition, but right now we will discuss a popular culprit in these conversations: chlorine.
Immediately, most minds switch to swimming pools and that itchy feeling of chlorine. However, chlorine is the most widely used disinfectant in water treatment facilities to ensure clean water from the treatment plant to your home. Since chlorine breaks down and evaporates quickly, it is difficult to ensure the proper level of chlorine when it reaches the sink faucet—as every home has a different travel time from the water treatment plant. In this way, homes can have a heightened level of chlorine, usually over a low level of it, to ensure proper disinfection of the water along the whole journey.
Using chlorine as a water disinfectant has been considered one of the greatest public health achievements of the 20th century, reducing the side effects of unclean water circulating the population with waterborne diseases. Additionally, the use of chloramine (chlorine plus ammonia) has also been a popular water disinfectant in recent times, for reasons we will discuss later. Overall, chlorine and chloramine are very useful in maintaining clean water; but additional unwanted health effects of having too much chlorine or chloramine in water can occur, as both are inherently toxic chemicals.
As mentioned above, both these chemicals are used in water treatment plants to disinfect water from bacteria growth and other unwanted particulates. Chlorine is a base element that exists naturally in nature and is used for much more than disinfecting water (i.e. PVC piping, chemical manufacturing, paper bleaching).
Chloramine, is again chlorine plus ammonia and works primarily as a water disinfectant, and is much more stable than chlorine. Chloramine, however, does not react with organics and create harmful byproducts as research has shown for chlorine; but chloramine is slightly more corrosive, can deteriorate rubber, cause pipe leaching, and is harder to remove with common filtration techniques.
As more and more research comes to light about the adverse effects of chlorination (too much chlorine) water treatment facilities have been switching to chloramine which has a few advantages. Namely, chloramine can exist in water for much longer periods than plain old chlorine can, increasing the time clean water can travel. This property is a benefit for water treatment facilities, but potentially a downside if homeowners are looking to remove both chlorine and chloramine from their water source.
Note: other water disinfectants besides chlorine have not been researched as extensively, so precaution should be taken when thinking chloramine or other disinfection methods are “better” than regular chlorine for human health.
As chlorine is very useful for intended purposes such as household cleaning, water disinfection, and paper bleaching, it is still very harmful to human health in high concentrations and prolonged exposure. The EPA has not distinguished it as a carcinogen, but as a strong irritant to the eyes, upper respiratory tract, and lungs in long term exposure instances. Therefore, it is essential to measure chlorine levels in drinking water.
The CDC recommends that drinking water has no more than 4 ppm (parts per million), or 4 mg/L, of chlorine in municipal drinking water. As levels of chlorine rise above this, acute side effects like itchiness and irritation can arise and become worse as levels continue to heighten.
Therefore, chlorine and chloramine can be harmful above certain concentration levels, especially if other health complications exist to amplify the effects of chlorination. If you are unsure about the quality and chlorine level of your water, reports can be generated online per zip code, or an ORP (oxidation-reduction potential) sensor can be used to measure water quality and indirectly measure healthy levels of chlorine to kick off the process. Understanding ORP measurements is essential when measuring chlorine in swimming pools.
First things first, harmful side effects of chlorination are discussed here with the assumption of long term consumption, not just one glass of water with high chlorine content.
Anyhow, one of the largest concerns with chlorine recently are the disinfection byproducts created when reacting with organics in the water or piping system: trihalomethanes. The U.S. EPA has set a limit of 100 parts per billion (ppb) for trihalomethanes (THMs) in drinking water for systems serving over 10,000 people. A study in 2023 found that higher concentrations of THMs (≥15 µg/L) in drinking water were linked to an increased risk of colorectal cancer in men, with a hazard ratio of 1.26 (95% confidence interval = 1.05-1.51), compared to those with no exposure.
On the other hand, chloramine does not react to form THMs, creating a potential solution in the water disinfection process, but many questions are still unknown about the safety of chloramine. In either case, there is still reason to question the content of your drinking water, and also that disinfectants are put in place to uphold public health. Both sides have weight and must be balanced.
Additionally, many people have heightened sensitivities to both chlorine and chloramine causing much discomfort if levels become too high in water applications. High levels of both substances also lead to
More severe issues as discussed above are not readily proven, but many eyebrow-raising effects have occurred in people with high percentages of chlorine and THMs:
If you are now slightly nervous about the contents of your drinking water, especially chlorine, you’re in the right place discussing how to remove chlorine and chloramine from your water.
The first step to removing chlorine is to see if it’s necessary to do so. This measurement can be done indirectly with an ORP sensor. Since chlorine reacts with bacteria and other microorganisms to eliminate them, this allows the ORP sensor to measure the intensity of this reaction potential.
Another option is a dpd (diethyl paraphenylenediamine) test. This test involves dropping dpd into the sample water and comparing the relative intensities of red color to a color scale—thus showing you the relative amount of chlorine in the water.
Other test kits exist on the internet, but keep in mind that the point of testing is very important. For consumers, most people want to know chlorine levels as it comes out of their faucet or after adding chlorine to a swimming pool, pretty straightforward. Industrial applications, however, will require more testing along water distribution channels to ensure proper chlorine levels are maintained throughout the whole process.
4 common, and effective, methods of removing chlorine and chloramine from water exist:
Various pump and filtration systems are available for consumer and industrial applications, but the basic concept is the same. The water, before reaching the end-user, is pumped through a membrane filter via reverse osmosis. Normally, water wants to balance out all the particles in it and will flow from a higher concentration to a lower concentration. In this instance, the water filter prevents the chlorine, chloramine, and other contaminants from passing to the lower concentration side, or the clean water side (i.e. reverse osmosis).
These filters usually occur in three main parts: large particle filter, carbon or charcoal filter, semipermeable membrane. The large particle filter acts as a prefiltration step and removes large particles like dust and dirt. The semipermeable membrane as the final step removes almost all the dissolved solids in water. Lastly, somewhere between the two, the carbon filter uses activated carbon to filter out volatile organics like chlorine and chloramine.
One thing to note, chlorine is easier to remove and will be filtered out by common activated carbon filters. On the other hand, chloramine is much harder to remove (since it is more stable) and requires more contact with carbon to be filtered out. In this case, catalytic carbon is used to filter out chloramine more effectively.
Some background research on filter choice should be considered if you are trying to remove chlorine, or chloramine, or both. If you’re trying to remove chloramine from water, a catalytic carbon filter will better serve the filtration efforts.
Chemical balancing, neutralization, or water purification are all leading towards the same result in this case: removing or breaking down chlorine and chloramine in water. In a similar way to balancing pH, more chemicals will be added to the water to reduce the amount of chlorine. Seems unintuitive, but that is the beauty of chemistry and balancing chemicals.
The most common and effective chemical to neutralize chlorine and chloramine is potassium metabisulfite, or Campden tablets (Campden tablets sometimes use sodium instead of potassium but the final result is the same). These tablets are often used in brewing operations to achieve the same disinfection results and remove chlorine. The Campden tablets are dissolved in water with ratios of 1 tablet per 20 gallons, take about 20 minutes to neutralize the chlorine, and then evaporate themselves.
These tablets may have a strong odor to them but are relatively inexpensive, remove chlorine and chloramine, and work quickly. To speed up the process, evaporation can be used after the Campden tablets have been given enough time to work.
As discussed previously, chlorine is a volatile chemical meaning it evaporates readily at normal temperatures. In this way, leaving water out on the counter will allow the chlorine to evaporate over time, and boiling the water will speed up the process even further.
Evaporation is a natural and cost-effective solution to the chlorine problem, requiring only time. However, this is only practical for small scale water applications for that reason. Additionally, since chloramine is more stable and is a non-reactive stable liquid it does not readily evaporate; so this method is ineffective for removing chloramine from water.
UV light is an extremely effective method of removing both chlorine and chloramine from water. It uses ultraviolet light to break down these chemicals, does not affect water taste, and performs the extermination in only a few minutes. Although, more exposure equals more breakdown of chlorine and chloramine.
These UV probes and applications can become increasingly more expensive, and do not filter out large particulates or dissolved solids. One must also be wary of long term exposure to UV light, in the same way being out in the sun too long without protection is harmful. These long exposure times shouldn’t be an issue with removing chlorine and chloramine from water, but a consideration nonetheless.
While UV filtration is energy-efficient, it still needs some electricity to work. If there’s a power outage at home, you’ll be left without filtered water. Additionally, UV filtration isn’t practical for campers or those in remote areas who need access to clean water.
Chlorine and chloramine are extremely effective water disinfection methods and account for a large portion of clean water for public health. However, too much of either chemical can cause unwanted side effects, some of which are still inconclusive, but worrisome, in the long term.
In either case, testing your water for increased chlorine and chloramine levels is always the first step in preventing these health effects. If removal of chlorine and chloramine are necessary, look to the four methods of removing these chemicals from water: water filtration, chemical balancing, evaporation, and/or UV light.
These methods can be combined, but certain methods will not remove both chlorine and chloramine. For example, water filtration with catalytic carbon is necessary to remove chloramine, whereas regular activated carbon will do fine to remove chlorine. Evaporation is also a great technique to remove chlorine but will not remove chloramine. The size and scale of this water removal process should also be considered when choosing a method.
Overall, everyone deserves access to clean drinking water. Water disinfectants make this possible all across the globe to reduce disease and other waterborne illnesses, but it’s always worth a peace of mind to test your water for heightened levels of chlorine and chloramine.
If you are unsure exactly what ORP device will best suit your needs to determine chlorine levels, do not hesitate to reach out to the world-class team at Atlas Scientific.
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