ISO 4831:2006 gives general guidelines for the detection and the enumeration of coliforms. It is applicable to products intended for human consumption and for the feeding of animals, and to environmental samples in the area of food production and food handling.

Enumeration is carried out by calculation of the most probable number (MPN) after incubation in a liquid medium at 30 °C or 37 °C.

This enumeration method is applicable when the number sought is expected to be in the range 1 to 100 per millilitre or per gram of test sample.