“Water is the driver of nature.”
~ Leonardo da Vinci
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National Secondary Drinking Water Standards and Other Aesthetic Contaminants

Secondary Contaminants

Contaminant

SMCL

WQA Recommended Treatment Methods

Effects on Water

Sources of Contaminant in Drinking Water

Alkalinity (as CaCO3)

  • No federal limit
  • Low : <30 mg/L
  • High: >300 mg/L
  • Raise: Soda Ash
  • Lower: White Vinegar, Citric Acid
  • Low alkalinity waters tend to dissolve minerals and metals
  • High alkalinity waters tend to precipitate minerals and metals
  • Presence of bicarbonates, carbonates, and hydroxides

Aluminum

  • 0.05 to 0.2 mg/L on case-by-case basis
  • Cation Exchange
  • Reverse Osmosis
  • Distillation
  • Ultrafiltration
  • Deionization
  • Colored or tinted water
  • Alum coagulation treatment
  • Natural deposits

Chloride

  • 250 mg/L
  • Reverse Osmosis
  • Distillation
  • Anion Exchange
  • Electrodialysis
  • Deionization
  • Salty taste
  • Natural deposits

Color

  • 15 (color units)
  • Anion Exchange
  • Activated Carbon
  • Filtration
  • Chlorination
  • Reverse Osmosis
  • Distillation
  • Ozonation
  • Visible tint
  • Tannins
  • Natural deposits
  • Iron
  • Copper
  • Manganese

Copper

  • 1.0 mg/L
  • Reverse Osmosis
  • Distillation
  • Cation Exchange (20%-90%)
  • Electrodialysis
  • Submicron Filtration
  • Blue-green coloration and staining
  • Metallic taste
  • Copper pipe corrosion
  • Natural deposits
  • Leaching from wood preservatives

Corrosivity

  • Non-corrosive
  • Calcite or Calcite/Magnesium Oxide
  • Soda Ash Chemical Feed
  • Polyphosphate Feed
  • Removal of Hydrogen Sulfide
  • Sodium Silicate Feed
  • Metallic taste
  • Corrosion
  • Fixture staining
  • Leaking plumbing
  • Very high or very low TDS
  • Dissolved gases in water, such as oxygen, carbon dioxide, and hydrogen sulfide
  • Low pH

Fluoride

  • 2.0 mg/L
  • Activated Alumina
  • Reverse Osmosis
  • Distillation
  • Electrodialysis
  • Spotting and mottling of teeth
  • Natural deposits
  • Fertilizer
  • Aluminum industries
  • Drinking water additive

Foaming Agents (methyl blue active substances - MBAS)

  • 0.5 mg/L
  • Chlorination
  • Activated Carbon
  • Ozonation
  • Reverse Osmosis
  • Distillation
  • Sudsing
  • Bitter taste
  • Odor
  • Detergent pollution
  • Surfactants
  • Pollution

Hardness (as CaCO3)

  • No federal limit
  • Soft: <17.1 mg/L
  • Slightly hard: 17.1 to 60 mg/L
  • Mod. hard: 60 to 120 mg/L
  • Hard: 120 to 180 mg/L
  • Very hard: >180 mg/L
  • Remove all calcium and magnesium ions with a cation exchange water softener
  • Consumes soap and makes cleaning more difficult
  • Whitish scale deposits
  • Soap curd and lime scum residue
  • Natural deposits causing calcium(limestone) and magnesium salts in raw water

Iron (Total)

  • 0.3 mg/L
  • Filtration(oxidizing filters)
  • Cation Exchange
  • Oxidation/Precipitation/Filtration
  • Disinfection
  • Rusty color
  • Sediment
  • Reddish or orange stains
  • Metallic taste
  • Natural Deposits

Manganese (Total)

  • 0.05 mg/L
  • Filtration (Oxidizing filters)
  • Cation Exchange
  • Oxidation/Precipitation/Filtration
  • Disinfection/Filtration
  • Dark brown-black stains
  • Bitter, metallic taste
  • Natural deposits

Methyl Tertiary-Butyl Ether (MTBE)

  • No federal limit
  • Activated Carbon
  • Air Stripping
  • Sweet solvent odor at 0.020 mg/L
  • Possible human carcinogen
  • "Oxygenator" additive for reformulated gasoline

Odor

  • 3 (threshold odor number)
  • Activated Carbon
  • Air Stripping
  • Oxidation/Filtration
  • Disinfection/Filtration
  • Rotten egg
  • Musty
  • Garlic
  • Chemical smell
  • Chlorine
  • Hydrogen sulfide
  • Organic matter
  • Gasoline contamination
  • Methane gas
  • Septic contamination

pH

  • 6.5 - 8.5
  • Increase by feeding soda ash
  • Decrease by feeding white vinegar or citric acid
  • Neutralizing filter (Calcite or Calcite/Magnesium
  • Corrosive water
  • High carbon dioxide
  • Natural balance of acid and alkalinity

Silver

  • 0.1 mg/L
  • Coagulation/Filtration
  • Submicron Filtration/Activated Carbon
  • Ion Exchange
  • Distillation
  • Reverse Osmosis
  • Skin Discoloration
  • Greying of white part of eye
  • Natural deposits
  • Industrial wastes
  • Water sanitizing agent

Sulfate

  • 250 mg/L
  • Reverse Osmosis
  • Distillation
  • Anion Exchange
  • Electrodialysis
  • Medicinal taste
  • Laxative effect
  • Natural deposits

Total Dissolved Solids (TDS)

  • 500 mg/L
  • Reverse Osmosis
  • Distillation
  • Deionization by Ion Exchange
  • Electrodialysis
  • Hard water
  • Deposits on glasses and fixtures
  • Natural deposits
  • Brackish water intrusion

Zinc

  • 5 mg/L
  • Reverse Osmosis
  • Distillation
  • Cation Exchange
  • Electrodialysis
  • Metallic taste
  • Industrial wastes
  • Natural deposits
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