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Sampling refers to the process of selecting a portion of the population to represent the entire population. The objective of sampling is to collect a portion of material small enough in volume to be transported conventely and yet large enough for analytical purposes while still accurately representing the material being sampled.

Selection of sampling:

The success and failure of water pollution survey shall depend largely upon the planning made prior to talking samples.

         Selection of sites in first place is decided on the basis of overall objective of program. Sampling point must be indicated to provide an accurate understanding of the existing water quality.

In organically polluted river at least one site should be selected above out fall of the wastes and fair sites should be selected.

Sampling collection techniques:

Samples may be collected by using different method.

i) Grab sampling:

      It is an ordinary sample which is taken from a particular place representing the whole water quality. This type of water sample is valid only when it is certain that the water quality is not changing.

ii) Composite sampling:

It is the one taken of various time from a locality undergoing fluctuation and combining that to know average chemical  characteristics. For eg: A stream water is revalving effluent at irregular time.

iii) Sampling potable water:

The most convenient point for sampling potable water is at the consumer’s premises.  Before collection samples from the distribution system inside and outside of the tap should be thoroughly cleaned.

No.of samples and frequency:

The number of samples required depends upon the object of the programme and the amount of time and effort to be put. It is more reliable to collect many samples from localities to know the actual status of sampling sites.

Sample handling and presentation:

Accurate sampling should be followed by connection handling and presentation of samples to obtain reliable results.


Hence the study techniques for the quality monitoring for water environment were studied .

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