Chlorine may be neutralized by ascorbic acid, sodium ascorbate and sulfur compounds. Natural methods, such as leaving the chlorinated water exposed to air and sunlight in tanks or ponds or dumping it in an external environment, are also effective.
Air and sunlight neutralize chlorine over time, allowing chlorinated water to be stored and de-chlorinated in natural environments without the use of chemicals. Sulfur compounds may be used to neutralize chlorine, but may have adverse effects on the environment since they lower oxygen levels in the water. Vitamin C, in the form of ascorbic acid, and sodium ascorbate quickly neutralize chlorine and are non-toxic. Ascorbic acid may slightly lower the pH level of the water, while sodium ascorbate is pH-neutral, and does not affect the pH of the water.