VPE 511: Environment and Environmental Hygiene (2+1)

COLLECTING FROM DIFFERENT SOURCES

• Tap in regular use
  • Open the tap fully. Allow water to run for 2 minutes to flush stagnant water at the end of the pipe.
  • From taps not in regular use, water is collected after sterilising the tap by heating with a blow lamp, till it is unbearably hot to touch.
  • Cool it, allow water to run for some time and then collect. Fill bottle from a gentle stream to avoid splashing.
  • Sampling frequency for public water supply is based on number of population served. 
• Collection from river, lake and reservoir-Grab sampling
  • It is the instantaneous collection of the required amount of water from appropriate source.
  • In rivers, sample should be collected away from bank and at some depth. For sampling, a sterile bottle with string attached to neck is used.
  • Another long string is tied to the end of sterilised string to lower bottle into water.
  • After filling, stopper bottle, cover with cloth and seal.
  • Two samples are collected one at the entry point and another at the exit point of the river. The same method is used for well water.