Objectives  To validate the feasibility of a method using lactose peptone broth in a kind of fermentation tube with observable cassette to detect Escherichia coli in water on wild fields.

Methods  Comparing the multiple-tube fermentation method used in the standard examination methods for drinking water with the lactose peptonein the observable-cassette fermentation tube method, Escherichia coli was test in water samples, including standard water samples prepared in laboratory and water samples collected from wild fields. The lactose peptone broth used in the multiple-tube fermentation method was prepared according to the national criteria; and the lactose peptone broth used in the observable-cassette fermentation tube method was from commercial kits.

Results  No significant difference was observed between the results in the observable-cassette fermentation tube method and the multi-tube fermentation method for standard water samples made in laboratory (t=0.539; P>0.05) or water samples collected from outdoors (t=0.772;P>0.05).

Conclusion  The observable-cassette fermentation tube method was easy to carry out and stable, which can be used to detect bacteria in drinking water, especially for performing test in outdoors.