The Cl- ion is present in small quantities on Earth.

 

The main source of chloride in water is solution of sedimentary rocks deposited in a marine environment, which have not been completely leached, and evaporites.

 

Ingress of seawater ( where Cl- is present in great quantities ) and evaporation phenomena in endoreic basins are also possible sources of chlorides ( the smaller the distance from the sea, the more significant the contribution made by precipitation ).

 

Human contributions ( e.g. from urine ) are minor.

 

• AEP standard upper limit is 200 mg/l.

• WHO recommendation ( taste ) : < 250 mg/l.​