Safe drinking water is vitally important to health. Both pathogenic and harmless bacteria can be found in the guts of mammals and birds. Testing water for every possible type of pathogenic bacteria is slow and costly. Thus, water is tested for a characteristic type of gut bacteria - the coliforms - including the familiar E. coli. Presence of coliforms is an indicator for faecal contamination. In this experiment, students test for coliforms in simulated contaminated water using colour and fluorescent reagents. They can use these same reagents to test water samples from the environment. As an extension activity, a Gram Stain test can be performed on the collected samples.

• For 10 lab groups
• Complete in 30 minutes and grow overnight

Also required: Long wave UV lamp, microscope, slides and coverslips.