Chloride in Drinking Water: Safe Limits & What You Should Know
Indicator of salinity
Optimal Min in Water
0
Optimal Max in Water
100
Unit
mg/L
Symbol
Cl
Who Limit
250
None
5 min read
Overview of Chloride in Drinking Water
What it is: Chloride (Cl) is the negative ion of chlorine, commonly found as sodium chloride (table salt). It's a natural component of all water sources and an essential nutrient for human health.
Why it matters: Chloride is a key indicator of salinity and potential contamination. Elevated levels can signal seawater intrusion, road salt runoff, industrial discharge, or sewage contamination.
Natural sources: Seawater is the ultimate source; coastal aquifers often have elevated chloride. Rock salt deposits, geothermal activity, and agricultural drainage also contribute. Urban runoff from road de-icing is a major seasonal source.
Optimal range (0–100 mg/L): Water tastes fresh and clean. No salty notes detectable. Suitable for all uses including low-sodium diets. Most pristine freshwater sources fall well within this range.
Too high (>250 mg/L): WHO guideline based on taste threshold. Water begins to taste salty or brackish. High chloride accelerates pipe corrosion, especially in older metal plumbing systems.
Contamination indicator: Sudden increases in chloride often indicate pollution—sewage leaks, landfill leachate, or industrial discharge. Monitoring chloride trends helps detect water quality problems early.
