Indirect methods of counting germs

The indirect method of determining the germ level has been used since the 

In the case of the indirect method of determining the number of germs, only those germs which have developed into colonies under the conditions employed 

In satisfactory ground water the colony number will not exceed the standard value of 100 per ml at an incubation temperature of 20 C. In the case of disinfected drinking water, the colony number should be less than 20 per ml after completion of the treatment processes. 

The bacterial count is defined as the number of colonies visible under 6 to 8-fold magnification which form in pour-plate cultures with nutrient-rich, peptonic culture mediums (1 % meat extract, 1 % peptone) from 1 ml of the water being analyzed after incubation at 20 2 C for H hours. 

---