Final answer:
Coliforms are a sign of fecal contamination in water, indicating potential presence of pathogens. Testing involves inoculating water samples into lactose broth and checking for color changes signifying coliform growth. Ensuring water is coliform-free prevents gastrointestinal illness.
Step-by-step explanation:
Coliforms are tested for in drinking water sources because they are an indicator of fecal contamination. These gram-negative rod bacteria that ferment lactose can be found as part of the normal gut flora of humans and many types of animals. The presence of coliforms, especially fecal coliforms like E. coli, suggests that the water has been contaminated by fecal matter, which can include disease-causing pathogens.
Testing for coliforms involves a method where water samples are diluted and inoculated into lactose broth tubes. The presence of coliforms is indicated by a change in the color of the broth due to lactose fermentation. A positive test necessitates further action to confirm the presence of pathogenic organisms and to ensure water safety.
Failing to maintain water free of contaminants like coliforms can lead to gastrointestinal illnesses, which underscores the importance of regular and accurate testing of drinking water sources.