Fact Sheet: Chloride


Brief Overview:
Contaminant: Chloride
Category: Inorganic
MCL: 250 mg/L (Secondary)
Source: Natural and human activities
Effect: Salty taste
Followup: Test for sodium if on sodium restricted diet
Treatment: Reverse Osmosis or Distillation

Source: Chlorides occur naturally in many areas of the country due to minerals in the soil that contain chlorides. Ground water in coastal areas may contain chlorides from salt water intrusion. Sea water contains tens of thousands of mg/l of chloride. Chlorides do not break down in ground water they simply move with the water flow. While an onsite septic system will break down some of the organic components, chlorides move through the system largely unchanged. Salt piles, especially if left uncovered, and deicing of parking lots and pavements can also influence the chloride levels in well water. Fossil fuel drilling can also release chlorides and the chemicals used in fracking contain chlorides.
The MCL for chlorides is based on The Secondary Drinking Water Standards set by the USEPA. The MCL is set for aesthetic reasons rather than a health risk. When water contains in excess of 250 mg/l of chlorides it can impart a salty taste. The salty part of table salt (sodium chloride) is the chloride.

Effect: Salty or bad taste, possible damage to plants and may be corrosive.

Followup: Excessive chloride levels may indicate excessive sodium levels in the water supply. Individuals who are on a restricted sodium diet should test the water for sodium even if the chloride level is within the MCL. Regular testing to track chloride levels over time.

Chlorides can be removed by reverse osmosis or distillation. Note, boiling the water only increases the chlorides.

For more information visit the USEPA web site: http://www.epa.gov/dwstandardsregulations/secondary-drinking-water-regulations-guidance-nuisance-chemicals