Have you ever wondered what the water you drink flows through before coming in contact with your body? Some of the water mains used to distribute drinking water are made of materials such as unlined cast-iron steel or cement-lined iron. While the study found the presence of Mycobacteria in both cast-iron and cement-line mains, it was observed that cast-iron mains sheltered an abundance of Disulfovibrio spp., a sulfate-reducing bacteria, which causes corrosion and affects the design life of mains. Despite the aerobic conditions of the drinking water distribution systems, the corrosion tubercles provide anaerobic niches that allow this bacteria to proliferate. The corrosion deposits protect bacteria from disinfectant residuals and provide nutrients that contribute to bacterial growth. Water mains that are highly corroded support higher densities of bacteria in comparison to those that are non-tuberculated or cement-lined as seen in the figure below. This study will aid in furthering research on how to improve the management and assessment of water distribution systems in order to limit the growth of sulfate-reducing bacteria.
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| From (Gomez-Smith, C. Kimloi et.al. 2015) This figure compares the bacteria present in cast-iron water mains(left) to cement-lined water mains (right). In the cast-iron water main, the presence Disulfovibrio causes corrosion tubercles. |
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