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Chloride

As ground water moves through bedrock or sand and gravel geologic deposits in the subsurface, it will dissolve different minerals and consitutents including chloride.   Chloride occurs naturally in ground water as a component of deposited salts in geologic formations.  The levels of chloride may vary in water wells depending on the type of rock the ground water moves through and how long the ground water is in contact with the rock and has the ability to dissolve minerals.  Deeper wells may have higher levels of chloride because the ground water has dissolved many of the natually occuring minerals over time.  Chloride levels in water wells that are higher than normal background levels may indicate that chloride has migrated into the ground water from other sources such as:

  • highway salt and salt storage areas,
    brines produced during oil and gas well drilling,
    sewage effluent,
    landfills,
    irrigation drainage,
    animal manure and fertilizers, and
    industrial waste.

The presence of chloride does not always mean the water is saline.  Water is considered saline when the total dissolved solids in the water reaches levels of 1000 mg/L and greater.  See the Total Dissolved Solids page for more information.

What are the Drinking Water Standards?

The USEPA has set a secondary maximum contaminant level (MCL) standard for drinking water at 250 mg/L or 250 ppm (parts per million).  Changes in taste, odor, and color may be evident when levels are greater than 250 ppm. 

The Ohio Department of Health has adopted this standard as a non-enforceable health-based standard for private water systems. 

The Ohio Department of Health has set a construction standard for the use of bentonite grout, during the construction of private wells, when the total dissolved solids in the water exceeds 1500 mg/L and chloride levels are 500 mg/L or greater as addressed in Ohio Administrative Code Rule 3701-28-09(G)(2)(c).  

The Total Dissolved Solids page will provide information about salinity (not to be confused with salt) and other inorganic chemicals such as carbonates, sulfates, nitrates, sodium, potassium, calcium, and magnesium.

What are the Health Effects?

There are no known health effects associated from chlorides.  Sodium, which is often associated with chloride, may be of concern with people suffering from heart or kidney disease.

What are the Treatment Options?

Effective treatment technologies include:

  • reverse osmosis,
    distillation, and
    ion exchange.

The treatment options, listed above, are not enforceable by the Local Health District or the Ohio Department of Health. These are recommended options for private water systems owners.

Additional Resources

Page reviewed 10/21/14