Does vitamin C powder added to water which has chloramine neutralize the chloramine?
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Executive summary
Vitamin C in the form of ascorbic acid (or its salt sodium ascorbate) chemically neutralizes chloramine in water by reducing the chlorine moiety, and has been demonstrated in practical guides and utility testing to eliminate chloramine in small-volume uses such as a bathtub or spa when dosed appropriately [1] [2]. Practical caveats — correct dosing, contact time, pH effects, and the difference between short‑term dechlorination and continuous whole‑house treatment — determine whether it is a suitable solution for a given use [3] [4] [5].
1. How the chemistry works: vitamin C reduces chloramine, not “removes” it like a filter
Ascorbic acid (vitamin C) and sodium ascorbate act as reducing agents that react with free chlorine and with chloramines to yield chloride and oxidized vitamin C products, so they neutralize the disinfectant chemically rather than physically filtering it out [1] [3]. That reaction is relatively fast — one review and hobbyist testing cites a chloramine–ascorbic acid half‑time on the order of minutes (about 4 minutes) — so a modest contact time is usually sufficient in batch situations like a bathtub or bucket [3].
2. Evidence from utilities and technical guidance: real-world demonstrations
Federal and municipal guidance documents and utility testing have recommended vitamin C for dechlorinating small volumes: the U.S. Forest Service summary of using vitamin C to neutralize chlorine lists ascorbic acid and sodium ascorbate as practical options for water systems [6] [1], and San Francisco Public Utilities (cited in public documents and secondary sources) reported that 1,000 mg of crushed vitamin C tablets fully neutralized chloramine in a medium‑size bathtub without substantially depressing pH [2] [7].
3. Dosing and form matter; sodium ascorbate is gentler on pH
Practical calculators and applied articles show dosing scales: small doses of ascorbic acid or slightly larger masses of sodium ascorbate per gallon are sufficient for typical municipal chloramine concentrations, and sodium ascorbate is recommended when pH change is a concern because it is less acidic than pure ascorbic acid (examples and calculators summarized in USDA/utility guidance and hobbyist experiments) [4] [6] [3]. Sources commonly recommend roughly grams per ppm per some volume, and utility resources provide dosing tables for disinfectant neutralization [1] [3].
4. Where vitamin C is practical — and where it is not
Vitamin C is widely recommended for single‑batch uses (baths, aquaria water changes, brewing small batches) and as the active chemistry in some shower filters because it neutralizes chloramine rapidly in that context [7] [8]. It is not a long‑term filtration medium for continuous municipal supply without regular re‑dosing or a designed system: vitamin C degrades in solution over a day or two and does not remove non‑chlorine contaminants; utilities and reviews emphasize activated carbon or sulfite (Campden) options for large‑scale or continuous removal because those address distribution‑scale flows and do not rely on continuous chemical dosing in the delivered water [3] [2] [9].
5. Tradeoffs, alternative viewpoints and implicit agendas in the reporting
Vendor and advocacy pieces often present vitamin C as an all‑purpose, “natural” cure for chloramine and chlorine exposure with marketing claims that overstate convenience [10] [7], while technical sources emphasize operational details: contact time, correct form and dose, pH impacts, and that the vitamin C reaction converts disinfectant to chloride (and in chloraminated water can produce ammonium species) rather than eliminating the ammonia component by volatilization [3] [1]. Carbon filtration and Campden (sulfite) treatments are offered by other stakeholders (brewers, utilities) as better fits for continuous or large‑volume dechloramination [2] [9].
6. Bottom line answer
Yes: powdered vitamin C (ascorbic acid) or sodium ascorbate will chemically neutralize chloramine when added to water, provided the correct form and dose and sufficient contact time are used, and it is especially practical for small, batch applications like baths, aquaria, or brewing [1] [2] [3]. However, it is not a filtration‑style removal for continuous municipal flows without engineered dosing or replacement systems, and users should account for pH changes (ascorbic acid) or choose sodium ascorbate to minimize that effect [6] [4].