MICROBIAL EVIDENCE LADDER
Recognizable genetic material associated with a bacterium is present.
Reached in some tanksIntact organisms are alive and able to reproduce under relevant conditions.
Not establishedPeople encounter enough viable organisms through a plausible route.
Not establishedThe exposure is shown to have caused illness.
Not measuredA metal test measures an element’s concentration and compares it with an applicable guideline. An elevated result does not by itself identify the source, reconstruct its route into the tank or demonstrate illness.
Culture tests, genetic assays, chemical measurements and randomized health trials answer different questions; their results are not interchangeable rungs from a single test.