If you search products that claim to remove chloramine from your shower water, you will most likely see an ocean of products that can be grouped into two categories: one uses activated carbon (almost all use regular activated carbon filter which we will also touch up on their effectiveness as chloramine shower filter), and the one uses vitamin C.
But can vitamin C really remove chloramine from shower water?
Types of vitamin C
There are several forms of vitamin C, including ascorbic acid, sodium ascorbate, calcium ascorbate, potassium ascorbate, magnesium ascorbate, or ascorbic acid with bioflavonoids. For the purpose of chlorine neutralization, it is ascorbic acid, the same form of vitamin C found naturally in food, and in most supplements.
Neutralization vs. removal
There is a difference between removing disinfectant from water vs. changing the disinfectant in water to a different substance. This is the exact difference between activated carbon and vitamin C shower filter. Activated carbon uses a process called adsorption to capture contaminants. Adsorption is the accumulation of aqueous contaminants on the porous, solid surface of activated carbon. The contaminants are thus removed from the filtered water. On the other hand, vitamin C only neutralize in a chemical reaction in which acid and a base react quantitatively with each other in the water, but nothing gets removed.
Source of claim
We have to understand where this claim that vitamin C can neutralize chloramine in shower water comes from before we can potentially address the question. In 2005, American Water Works Association (AWWA) published their latest standard of Disinfecting Water Mains in AWWA C651-05, adding ascorbic acid as one of the methods for dechlorination of disinfected water mains. It then was quoted by San Francisco Public Utilities Commission (SFPUC) as the supporting evidence that vitamin C can be used to “remove” chlorine AND chloramine from shower. But hold on, there are a few catches.
In AWWA C651-05, everything is regarding chlorine. There is no mentioning about chloramine. It is the same as another publication by the U.S. Forestry Department. In that article, vitamin C again is mentioned to be used to neutralize chlorine, not chloramine.
In AWWA standard, the dose of vitamin C is listed for different level of chlorine neutralization. But there is no contact time. Contact time is probably not needed for disinfected water mains as sufficient contact time is probably assumed when a dose of vitamin C is put into a water body that sits out there. But when the scene changes to your shower room, will that assumption still holds?
Our own field test
With all these questions, we have chosen one popular vitamin C shower filter to see its actual performance in chlorine and chloramine neutralization. We use Hach Pocket Colorimeter to give us accurate and consistent test results. What we found is that vitamin C can neutralize chlorine in shower water very effectively. But as far as chloramine in concerned, vitamin C has ZERO effects.
More question regarding contact time
While AWWA standard does not mention the neutralization effects of vitamin C on chloramine, it is possible that it can still have neutralizing effects on chloramine over a longer period of time. The key here is contact time, or the time vitamin C will need to deliver its neutralization effects. There is no research or official publication that we can find on it. We did find one piece of related information from an Australian water filter company. It also quoted SFPUC’s claim that vitamin C can be used to neutralize bath water, but added that vitamin C dose has to sit in the bath tub for 4-8 minutes to allow chloramine neutralization. If that is the case, all the vitamin C shower filter will not work on chloramine, consistent to our field test.
Contact time of regular activated carbon in chloramine removal
One last word about contact time, and it is related to using regular activated carbon for chloramine removal. It has been researched and understood by the industry that regular activated carbon will use three to four times more contact time to remove chloramine compared to chlorine. And the contact time of a shower filter is much shorter than the time regular activated carbon would need to remove chloramine. That’s the reason why regular activated carbon filter does not really remove chloramine. Or it only works at the very beginning for a very short period of time. Catalytic carbon resolve the issue by having much more powerful catalytic property that can decompose chloramine (chloramine breaks into chlorine and ammonia) through chemical reaction upon contact, leaving chlorine to be adsorbed by the porous carbon substrate.