Chloride is formed when chlorine gas dissolves in water but is also a dietary mineral needed by the body for optimum health. Chloride makes up about 0.15 percent of our body weight. Chloride in the diet works with potassium and sodium, the two electrolytes, to control the flow of fluid in blood vessels and tissues, as well as regulating acidity in the body, and also forms part of hydrochloric acid in the stomach.

Chloride is commonly used as sodium chloride, such as in salt tablets, to help replace the sodium and chloride lost in perspiration on hot days or with exercise. Chlorine is used in treating drinking water, swimming pools, hot tubs, and so on to kill bacteria and other microorganisms.