There are different kinds of Bacteria that can be tested. Each individual site can show signs of Bacteria contamination based on appearance, smell, taste and watching for illness in both pets and humans. The Centers for Disease Control (CDC) recommends that you test private wells once a year for Bacteria. Use the link below to access their website.
Bacteria - Total Coliform
Escherichia Coliform Bacteria (E.Coli)
Heterotropic Plate Count
Sulfate Reducing Bacteria