Calcium Chloride is another salt that can introduce chloride ions into the groundwater.

Chloride is the Cl- ion of numerous salts, including the ubiquitous NaCl (ocean and table salt).

Chloride in a well is associated with infiltration of road salts, fertilizer, backwash from a water softener and even seawater.

It is not considered a health hazard.  However, an aesthetic standard exists:  the average person notices a salty taste when chloride hits  250 mg/L.

Chloride can impact household plumbing: it increases the conductivity of water, and is therefore more corrosive of metal plumbing pipes.  As the pipes are corroded, metals are dissolved into the water passing through them.

Health Limit

Not established.

Aesthetic Limit

USA Secondary Drinking Water Standard limit: 250 mg/L

Additional Resources

Wikipedia: "Chloride" 

World Health Organization, "Chloride in Drinking-water: Background document for development WHO Guidelines for Drinking-water Quality" (1996, 9 pg. pdf)

Sodium and Chloride in Drinking Water Wells, University of Rhode Island (2 pg. .pdf)

MEL Test Methods for Chloride

Wastewater –EPA Method 300.0 (NPDES Compliant)
Solids –Method 9056, 9056A (SW846 /RCRA Compliant)

Sample Requirements

Wastewater:

Container: plastic, glass
Volume: 60 mL
Hold Time: 28 days
Preservation: ≤6°C

Solids:

Container: plastic, glass, baggie
Volume: n/a
Hold Time: 28 days
Preservation: ≤6°C