ABSTRACT
The issue of "unsafe" bacterial samples due to coliforms and high bacterial counts has become a more critical issue, partially due to changes in regulations. The frequency of wells experiencing "unsafe" bacterial samples and the concern of this issue is increasing. A most common scenario is that an "unsafe" result is returned from the laboratory for a given sample and a repeat sample is tested which then comes back negative. It is most important to understand this when taking samples from a well since this is a pumped water sample and is not totally representative of the populations attached to surfaces in both quantity and bacterial types. Sometimes solving these problems can develop into absolute nightmares as we try to achieve "safe" samples with total coliform negative results. Another reason for the increased frequency of occurrence in the numbers of positive total coliform tests is the adoption of new criteria and testing procedures.
