Question

What causes chlorides in water?

Answer 1

There are several possible causes.

Explanation:

(1)
By leaching out chlorides from the soil
(2)
By chlorinating the water for safety. The hypochlorite that is used for this purpose, is converted into chloride.
(3)
By contamination with sea water. Sea water contains about 3-4% of chlorides. If the water intake point in a river is relatively close to sea, it can take in extra chlorides at high tide.