Dechlorination of water aims to remove the chlorine or chloramine in the water systems before consumption. Usually, tap water is commonly chlorinated in order to purify it or kill microorganisms. However, high levels of chlorine intake are not good for humans and even to other organisms such as fishes and other sea creatures. To attain that problem, dechlorinating tablets are being used in order to reduce the chlorine to a less toxic substance chloride.
Common dechlorinators are the sodium thiosulfate. This compound is not toxic to humans and has wide range of usage in the industry. The reaction of the tablets produces protons which decreases the pH of the water but not drastic. Other compounds used are Sodium hydroxymethanesulfonate and Sodium hydroxymethane sulfinic acid which is used for marine systems does affect the pH but not so much as well.
The reaction of Chlorine with sodium thiosulfate can be written as:
`Na_2S_2O_3 + Cl_2 + H_2O -> Na_2SO_4 + S + 2 H^(+) + 2Cl^(-)`
Some people use vitamin C to dechlorinate the water. Although it is not as effective, it can also lower the pH levels of the water system.