Chemical Characteristics of Drinking Water

Chemical Characteristics

• H2O is the chemical formula for water.


• Water's capacity to "stick" to itself and other surfaces is due to its unusual form, which has both hydrogen atoms on the same side of the oxygen atom.


• The hydrogen atoms provide a positive electrical charge, whereas the oxygen atom produces a negative electrical charge.

Total Dissolved Solids (<500)

• Total solids can be found by evaporating a sample of water and weighing the dry residue left.


• Suspended solids can be found by filtering a water sample through Whatman filter paper No.44


• The maximum number of solids that can be present in water is usually regulated at 500 parts per million (ppm).

pH (6.5 to 8.5)

• It is measure by hydrogen ion concentration in water.


• It is measure by Potentiometer and Colorimetric method

Alkalinity & Acidity

• Alkalinity is caused by bicarbonates of Ca & Mg and carbonates, hydroxides of Ca, Mg, Na, K.


• Alkalinity effect - Incrustation and sediment deposit in pipelines and difficult in chlorination.


• Acidity is caused by Mineral Acids, Free Co2, Sulphates of Fe & Aluminum.


• Acidity effect - Tuberculation & Corrosion of pipelines.


• Alkalinity and Acidity are estimated by Titrimetric.


• Total Alkalinity < 200 mg/l as CaCo3

Hardness (<200 ppm)

• It is measured by the EDTA test( Versante method)


• Temporary hardness caused by Bicarbonates and carbonates of Ca & Mg


• Permanent hardness caused by sulfate, chloride, and nitrate of ca & Mg.


• 1 French degree hardness = 10 ppm


• 1 British degree hardness = 14.25 ppm


• 1 American degree hardness = 17.15 ppm

Content of Chloride

• The chloride concentration of treated water intended for public consumption shall not exceed 250 parts per million.


• By titrating the water with a standard silver nitrate solution and using potassium chromate as an indicator, the chloride level of the water may be determined.

Nitrogen

• The presence of nitrogen in water can be caused by any of the following factors.
  
  
  
  • Free ammonia
  
  
  • Organic or Albuminous Matter
  
  
  • Nitrites
  
  
  • Nitrates

Toxic Chemical Substance (Drinking water Standards)

• Barium: - < 1 mg/l


• Lead: - < 0.1 mg/l


• Boron: - < 0.01 mg/l


• Cadmium: - < 0.01 mg/l


• Arsenic: - < 0.05 mg/l


• Chromium: - < 0.05 mg/l


• Cyanide: - < 0.05 mg/l


• Phenols: - < 0.001 mg/l


• Mercury: - < 0.001 mg/l

Thanks,

Kumar Bhanushali