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Sampling Procedure
  SAMPLING FOR CHEMICAL EXAMINATION
Water for chemical examination should be collected in a clean, white 2 liter polythene container.
The source from which water is collected should be in regular use. Otherwise the source should be adequately flushed before sampling. For hand pump sources, the water should be pumped and wasted for at least three to five minutes to clear all dirt, slime and turbidity. Water from wells should be taken in the middle at mid depth. For lakes, rivers and dams, the water should be collected near the off-take point.
Before collection of sample, the container should be washed with the water to be sampled for at least 2 to 3 times.
The water should be then filled completely in the container without leaving any air space.
Place the inner cap. Place a polythene sheet (10x10 cm) in between the inner and outer caps. Screw the outer cap. Place another polythene sheet of same size over the outer cap and tie the neck with a rubber band or twine thread.
Label the container with all required source particulars.
The sample should be delivered to the lab within 24 hours from the time of collection.
 
 SAMPLING FOR BACTERIOLOGICAL EXAMINATION
For bacteriological examination, the water should be collected only in a pre sterilized 250 mL glass bottle which is supplied from the laboratory after remitting the testing charges.
The sample collection procedures will be explained in the laboratory when the sampling bottles are delivered to the customer.
The sample should reach the laboratory within 6 hours from the time of collection. However when preserved in an icebox, the sample can be delivered within 24 hours.
The sample should be labeled properly before it is despatched.
 
 For further technical details contact
Chief Water Analyst,
TWAD Board,
No. 31, Kamarajar salai, Chepauk,
Chennai - 600 005
Ph: 28412098
E.mail:twadboard@dataone.in