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Secondary Constituents

Secondary constituents are regulated in public drinking water. They are called "secondary," instead of primary, because they have no adverse health effects.

Constituent Secondary Maximum Contaminant Level      (mg/L except where stated otherwise) Effects
Chloride 300 salty taste
Color 15 color units tinted water
Copper 1.0 metallic taste; blue-green staining
Corrosivity Non-corrosive metallic taste; staining
Fluoride 2.0 tooth discoloration
Foaming Agents 0.2 frothy or cloudy water; bitter taste
Hydrogen Sulfide 0.05 rotten-egg odor or taste
Iron 0.2 rusty color; sediment; metallic taste; staining
Manganese 0.05 dark color; staining; bitter metallic taste
Odor 3 Threshold Odor Number rotten-egg odor
pH >7.0 bitter taste; deposits; slippery or soapy feel
Silver 0.1 skin discoloration; greying of the white portion of the eye
Sulfate 300 salty taste
Total Dissolved Solids (TDS) 1,000 hardness; deposits; colored water; staining salty taste 
Zinc 5.0 metallic taste

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