Direct counting of germs

A counting chamber can be used to determine the number of bacterial cells in water. In such a chamber, the number of bacterial cells in a particular, small quantity of water (e.g. a cube with 0.1 mm sides = 0.001 mm ) can be counted under a microscope. Each bacterial cell determined in such a cube represents 10 germs in 1 ml. Thus, in order to determine a bacterial count at all with this method, the germ content of the water must be very high. This direct counting method cannot be used for water containing low levels of germs. 

Direct methods of counting germs are very time-consuming and inexact and are therefore as a rule not employed in microbiological water analyses. 

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