Water Well Journal
Issue link: http://read.dmtmag.com/i/692787
A s the revised total coliform rule (RTCR) became mandatory in April, all public water systems are required to accept new criteria and treatment techniques for addressing possible sanitary defects. The group of bacteria for which the rule is named after was previously adopted for such a role, with the imple- mentation of the original total coliform rule (TCR) in 1989. Since that time the analytical meth- ods used for monitoring coliforms, com- monly known as "Bac-T" tests, have jumped to the forefront of bacterial test- ing in the water industry. The notoriety these methods have gained as a result of these regulatory actions has not been unexpected. However, the general understanding of biological testing and its ability to provide additional insight into the foul- ing potential and operational aspects of a well has, in large part, taken a back seat to coliform testing. Even worse, misconceptions regard- ing the interpretations of Bac-T testing results have risen, leading to a state of confusion with suppliers, regulators, and consumers alike. The presence of specific bacteria within our water supplies can undoubt- edly pose risks to human health and have been known to do so for hundreds of years. However, bacteria can also be responsible for a number of other unde- sirable impacts—including foul odors, corrosion, production losses, and tar- nished aesthetic properties. The ability to account for other species of bacteria responsible for bio- fouling and assess the overall biological load can be a valuable tool in extending the life of a well and preventing costly maintenance procedures. Increasing de- mands on produced water quality and a greater emphasis on asset management are resulting in a growing need within the industry for more accurate monitor- ing of water wells and the fouling mech- anisms they are susceptible to. Beyond the Coliform "Bac-T" testing, coined from the methods available for coliform detec- tion, has become the industry standard for determining drinking water's sani- tary quality due to regulatory actions put in place by the U.S. Environmental Protection Agency. A group of closely related bacteria, coliforms have earned the role of "indicator" organisms due to their similarities to a variety of bacteria, parasites, and viruses all known to be harmful if consumed. Simply put, the presence of coliforms in water suggests the probable presence of other known pathogens—disease- causing organisms. The water industry has come to rely on this renowned organism as an answer to the impractical alternative of testing directly for the numerous pathogens potentially inhabiting a water supply. Yet, the practicality of this method does come with a few qualifiers. First, "col- iform" does not refer to a single species of bacterium. Rather, coliforms are a large group of bacteria, most of which occur naturally in the environment and pose little risk if consumed. In reality, only a small percentage of coliforms are pathogenic. Thus, the designation between total coliform and fecal coliforms is important to consider. Fecal coliforms, which include Escherichia coli, are the organisms of most sanitary significance as they are commonly found in the feces of warm- blooded animals and accordingly indi- cate a true contamination event. Additionally, the presence of col- iforms only suggests the potential pres- ence of more problematic organisms; they don't confirm it. And more impor- tant, the absence of coliforms doesn't confirm a water sample is free of harm- ful microorganisms. To illustrate this point, in the most recent Centers for Disease Control and Prevention's Surveillance for Water- borne Disease Outbreaks Associated with Drinking Water report, Legionella was found to be responsible for 66% of all the drinking water–associated dis- ease outbreaks from 2011-2012. All other non-Legionella bacteria collec- tively accounted for just 16% of the confirmed outbreaks. Legionella is a pathogenic group of gram-negative bacteria including the species L. pneumophila, responsible for Legionnaires' disease. Yet they are not detected by coliform testing. The Biological Fouling Mechanism As the groundwater industry contin- ues to adapt to the ongoing challenges of production and water quality, devel- oping a better understanding of the foul- ing mechanisms impacting our wells is essential. While Bac-T testing gives some indi- cation of the sanitary conditions of water, it does not consider the role bac- teria play in fouling outside of the con- text of potential health risks. In reality, bacteria have the means to influence production, materials, and water quality through a number of tactics. Perhaps the most influential bacterial fouling mechanism is the formation of biofilm. Biofilm is a naturally occurring expression of bacteria resulting from the extrusion of a slimy polysaccharide exopolymer. Bacteria exude this slime as a means of attaching themselves to a smooth surface for propagation, nutrient capture, and growth. Biofilms act as suburban communities within a well system, developing in numerous loca- tions and supporting a combination of different types of bacteria, including aerobic (oxygen present) and anaerobic (oxygen absent) organisms. TESTING continues on page 20 (Left) Multiple methods for the identifi- cation of bacteria and microbial activity. The Mysterious "Bac-T" Test Understanding biological testing. By Eric Duderstadt Twitter @WaterWellJournl WWJ July 2016 19