Removal of Chlorine Residual in Tap Water by Boiling or Adding Ascorbic Acid

Society’s preference for bottled water mainly comes from a dislike of the mildly pungent taste and odor of tap water. Such odor and taste may be caused by chlorine residual (in the form of free chlorine or chloramines), which is maintained in a water distribution system to prevent regrowth of microorganisms and is thus present in tap water. To encourage individuals who drink bottled water to shift to tap water, which affords numerous financial and environmental advantages, a simple, effective and low-cost method of reducing chlorine residual in tap water is essential. Two methods of reducing chlorine residual, boiling tap water and adding ascorbic acid to tap water, were tested. The results showed that, for free chlorine, a quick and cheap way to reduce chlorine residual is to add ascorbic acid, which if added in an equal molar amount to free chlorine would completely eliminate chlorine residual within 1 min. For monochloramine, a quick and cheap way to reduce chlorine residual is also to add ascorbic acid, but in greater quantity due to some ascorbic acid being oxidized by oxygen in the air. Although boiling is slower, it is effective in removing low concentrations of chlorine residual.