Total Count

Total Count

Total Count -The total count, also called colony count and standard plate count, gives the total number of microorganisms, comprising bacteria, yeasts and moulds, in a water sample.
It is usually done by pour plate method. In this method, a known volume of water sample is mixed with the molten Yeast-Extract Agar in petridishes and allowed to set.
One set of plates are incubated at 37°C for 24 hours and another set of plates are incubated at 20-22°C for 3 days. Most bacteria capable of growth in water will do so better at 22°C than at a higher temperature.

Organisms which grow best at 37°C will grow less readily in water. Since, these two groups of organisms differ in their significance, they have to be counted separately.
Though the colony counts are not essential for assessing the safety of potable water supplies, they are useful for indicating the efficiency of certain processes in the water treatment, such as coagulation, flocculation and disinfection. In addition, they also indicate the cleanliness of the distribution system.
They can also be used to determine the suitability of a water supply for the large-scale preparation of food and drink. The most useful application of the colony count is to detect change in the heterotrophic bacterial content of certain water.

Home | Site map | Submit Article | Directory | Search