Important Points in Water Supply Engineering

  • Water is considered ‘hard’ if its hardness is of the order of of over 250 ppm.
  • In general for drinking water the total hardness should not exceed 200 ppm.
  • One American degree of hardness is equal to 17.15 ppm
  • One French degree  of hardness is equal to 10 ppm.
  • One British degree  of hardness is equal to 14.25 ppm.
  • Safe and wholesome water is the one which is unpolluted, free from disease producing bacteria, toxic substances as well as excessive amounts of minerals and organic matter.
  • Soap is a sodium salt of stearic acid.
  • Ethylene Diamine Tetra Acetic acid (EDTA) solution is used to determine hardness of water.
  • Temporary hardness in water is caused bicarbonates of Ca and Mg.
  • Higher value of pH indicate stronger alkalies.
  • A water having pH value less than 7 is classified as acidic.
  • A water having pH value more than 7 is classified as alkaline.
  • A water having pH value equal to 7 is classified as  neutral.
  • pH value of water indicates both acidity and alkalinity.
  • The threshold odour number (TON) for a water sample of 40 ml, diluted to standard 200 ml mixture in which ouder is just barely detectable to the sense of smell is 5.
  • The flavour threshold number (FTN) and threshold number (TON) for the dring water should not exceed 3.
  • The color of water for domestic supplies on standard platinum-cobalt scale should not exceed 25 units.
  • One standard unit of turbidity is the turbidity produced by one mg of silica in one liter of distilled water.
  • A simple instrument is used for the measurement of color in water is called tinto meter.
  • With the Help of Hellige turbidimeter one can measure turbidity in the range of 0 to 50 ppm.
  • Baylis turbidimeter as compered to Jackson turbidimeter can preferably be used to measure turbidity in the range 0 to 2 ppm.
  • The turbidity of a specified concentration of formazin suspension is defined as 40 NTU.
  • On standard silica scale, turbidity in drinking water should be limited to 10 ppm.
  • The turbidity which can be seen easily by nacked eye is of the order of 5 JTU.
  • The turbidity is produced by one mg of silica ( silicon dioxide) in one liter of distilled water is termed as one Jackson turbidity unit (JTU).
  • The apparatus in which the measurement of turbidity is based on the intensity of light scattered at right angle to the incident light is called nephelometer.
  • The amount of light absorbed or scattered by suspended material present in water is a measure of turbidity.
  • Turbidity is measured on standard silica scale.
  • ‘Safe water’ is one, which does not contain pathogenic bacteria.
  • Water is said to be contaminated, if it contains pathogens.
  • The polluted water is one which contains  undesirable substances rendering it unfit for drinking and domestic use.
  • Low lift pumps are generally required to feed water in to treatment plant.
  • High lift pumps are generally required to feed water in to distribution system.
  • The most commonly adopted pumps in water supply schemes are centrifugal pumps.
  •  The water supply to a house house begins with the connection of the service pipe with the municipal water mains. The connection comprises : Ferrule, Goose neck, Stop-cock and Water mater.

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