RAPID: Assessing microbiological quality across point-of-use filters deployed in Flint, Michigan

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1632974LoveOne of the major issues facing the water and wastewater industry is aging infrastructure, some estimate that this is a one trillion dollar issue to be solved in the coming years. Flint, MI, is currently suffering from a "perfect storm" attributable to out-of-control corrosion of its potable water distribution system. In addition to concerns about lead, there are excessive disinfection by-products in the water, and, the poor bacterial quality associated with drinking water is also of concern. As one measure of protection to consumers, faucet-mounted point-of-use filters are being deployed for long-term use in the city at a scale not previously seen in the US. This project will investigate point-of-use filters for Flint water, with particular attention to the potential for changes as the water and infrastructure warm in the summer months.Well maintained point-of-use devices will certainly remove some of the chemical water contaminants; however, the opposite is typically true for microbiological contaminants. Previously, the PIs have shown in multiple and repeated tests that point-of-use filters increase the abundance and alter the composition of microbial communities in drinking water, even when filters are used in accordance with manufacturer guidelines. The PIs work has also shown that trace levels of a surrogate unregulated disinfection by-product altered the composition of the microbial community in the effluent of a point-of-use filter, suggesting that contaminants in the drinking water coupled with use of a point-of-use device alters the microbial risk a consumer is exposed to. In the case of Flint, it is not known how recovery of the distribution system and premise plumbing from the corrosion period will impact the microbial water quality applied to the point-of-use filters, and how influent changes will, in turn, influence the microbial quality of the water produced by the filter. Furthermore, it is unreasonable to think that a single point-of-use device on a faucet is sufficient, given that it does not achieve the conventional drinking water treatment paradigm that is to use multiple treatment barriers to protect public health from multiple contaminants. The PIs have extensive experience interrogating point-of-use filters like those used in Flint for changes in water quality, microbial abundance and composition using a range of current methods and can mobilize quickly. The PIs propose to complete a sampling campaign of faucet mounted point-of-use filters in Flint, Michigan over the spring, summer and fall 2016 to evaluate changes in the microbiological quality of point-of-use-treated water. The analyses will include culture-based and culture-independent methods to determine microbial community composition, specific species and/or genes that can impact public health. It is hypothesized that there will be higher levels of microbial growth across the system during the summertime. Previous studies showed significantly elevated levels of Mycobacterium, a family of bacteria known to include opportunistic pathogens, in the filter housing and moderate yet significant increases in the filter effluent. The importance of point-of-use filters in mitigating the chemical contaminants of concern is acknowledged, but a balance is needed to achieve acceptable microbiological water quality. Given the unknown consequences of the corrosion damage of Flints drinking water pipes on the microbial quality and disinfectant residuals in the distributed water, it is important to evaluate the microbiological quality of point-of-use filters in order to establish good monitoring and filter maintenance practices to assist in setting a point-of-use filter maintenance strategy for Flint, which is a major outcome of our proposed effort. This is particularly important to engage in immediately and through the rest of this year since the use of filters is expected to continue for several months.