A hypochlorite is an ion composed of chlorine and oxygen, with the chemical formula ClO−. It can combine with a number of counter ions to form hypochlorites, which may also be regarded as the salts of hypochlorous acid. Common examples include sodium hypochlorite (household bleach) and calcium hypochlorite (bleaching powder, swimming pool "chlorine").

Sodium Hypochlorite (NaOCl) is a compound that is effectively used for disinfecting water. Besides, it is used on a large scale as a detergent and surface disinfectant, bleach and deodorizer. The solution of NaOCl is very pale yellow color, with the characteristic odor of chlorine. NaOCl is a very strong oxidant; therefore it reacts strongly with inflammable compounds generating dangerous combustion.1

Calcium hypochlorite (Ca(OCl)2), commonly known as "bleaching powder" or chloride of lime is widely used for disinfecting water supplies. Its various forms are typically used for small applications of chlorine such as small water treatment plants or well water sites. Dry calcium hypochlorite is the most commonly used form of dry bleach in North America.2 The compound requires special storage to avoid contact with organic material. Its reaction with any organic substances can generate enough heat and oxygen to start and support a fire. When Ca(OCl)2 is mixed with water, heat is given off. To provide adequate dissipation of the heat, the dry chemical should be added to the water; the water should not be added to the chemical.3


  1. Disinfection by Sodium Hypochlorite: Dialysis Applications. Claudio Ronco, Gary J. Mishkin
  2. White's Handbook of Chlorination and Alternative Disinfectants. Black & Veatch Corporation
  3. Water Treatment. American Water Works Association, Jan 12, 2011 - Water