A key hypothesis of our National Science Foundation RAPID grant is that the rapid corrosion of iron water mains in Flint would dramatically increase growth of Legionella in buildings. Mechanistically, higher rates of iron corrosion will produce: 1) higher iron in water, and 2) lower levels of free chlorine. Both of these factors were confirmed to be present in Flint during our field sampling, and have been shown to dramatically increase Legionella regrowth in our recently published laboratory research utilizing simulated distribution systems.^1-5

Additional research is needed to examine the basis of this relationship.

1. Masters, S., and M. Edwards. Increased Lead in Water Associated with Iron Corrosion. Environmental Engineering Science, (2015), 32 (5), 361-369.
2. Masters, S.M., Wang, H., A. Pruden and M. Edwards. Redox Gradients in Distribution Systems Influence Water Quality, Corrosion, and Microbial Ecology. Water Research, (2015), DOI: 10.1016/j.watres.2014.09.048.
3. Wang, H., Masters, S., Edwards, M.A., Falkinham, J.O. III, and A. Pruden. Effect of Disinfectant, Water Age, and Pipe Materials on Bacterial and Eukaryotic Community Structure in Drinking Water Biofilm. Environmental Science & Technology. dx.doi.org/10.1021/es402636u.
4. Wang, H., S. Masters, Y Hong, J. Stallings, J.O. Falkingham, M. Edwards and A. Pruden. Effect of disinfectant, water age, and pipe material on occurrence and persistence of Legionella, mycobacteria, Pseudomonas aeruginosa, and two amoebas. Environmental Science & Technology 46 (21), 11566-11574 (2012).
5. Wang, H., Masters, S.; Falkinham, J.O.; Edwards, M.; and A. Pruden. Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters. Environmental Science & Technology. (2015), DOI: 10.1021/acs.est.5boa.538

Author: Dr. Marc Edwards