Explanation of Tests:  Chloride

Chloride is present in water in its ionic form.  Too much chloride is problematic for humans because of its association with sodium.  According to the EPA, the desired concentration of chloride in drinking water is 25 ppm, and the maximum permissible concentration is 250 ppm.  This means that any amount exceeding 250 ppm is considered hazardous to humans for consumption.  To put this into perspective, sea water contains about 35,000 ppm chloride.

(http://campus.hws.edu/ACA/sci-on-sen/chloride.html)