Bacteriological Analysis of Water

Bacteriological Analysis of Water

Bacteriological Analysis of Water
The first step in the bacteriological analysis is sampling. Samples of water or sewage for bacterial analysis should be collected in suitable bottles that have been carefully cleaned, rinsed in clean water (preferably distilled water) and sterilised.

Two kinds of bottles may be used: (1) clean sterile bottles and (2) clean sterile sodium thiosulphate-treated bottles. Water or sewage effluents containing residual chlorine should always be collected in sodium thiosulfate-treated bottles.

All other samples may be colleted in clean sterile bottles. In collecting samples, extreme care should be exercised to avoid contaminating parts of the bottle coming in contact with the water. The stopper should be handled without removal of the protective cover. Bottles should be filled to three-quarters of their capacity. If samples are collected in sodium thiosulphate-treated bottles, care must be exercised not to rinse the bottle and lose the sodium thiosulphate.

All samples should be tested as soon as possible. In warm weather, if the transportation period exceeds one hour, the sample should be iced. The time for transportation and storage should not exceed six hours for impure waters and 12 hours for relatively pure waters. Samples should be stored at a temperature between 6° and 10°C.

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