Chloride

What is Chloride?
Chloride is a naturally occurring mineral in drinking water and comes from mineral salts in the environment. The most common are hardness salts e.g. calcium. Chloride is a component of Sodium Chloride [NaCl] or table salt and is part of a normal diet. Sodium Chloride is also used to manufacture industrial chemicals i.e. Chlorine, Caustic Soda, Sodium Chlorite and Hypochlorite. It is also a component of Potassium Chloride which is commonly used as a fertilizer, in medicine, scientific applications and food processing. In the Drinking Water Regulations, it is defined as a Chemical parameter.
What is an exceedance of Chloride?
The limit designated to Chloride in the EU drinking water directive is 250mg/l. Therefore, any result above this level is an exceedance for Chloride.
How can an exceedance of Chloride occur?
The presence of excessive chloride in water supplies more than 30 kms from the coast is an indicator of pollution. Because sewage is such a rich source of chloride, a high result may indicate pollution of water by a sewage effluent. Natural levels in rivers and other fresh waters are usually in the range 15-35 mg/l Cl – much below drinking water standards.