Biogeography of Drinking Water Bacteria Along a Premise Plumbing Flow Path

EPA Grant Number: F13E10820
Title: Biogeography of Drinking Water Bacteria Along a Premise Plumbing Flow Path
Investigators: Kotlarz, Nadine
Institution: University of Michigan
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2014 through September 1, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Environmental Engineering


Most of the U.S. population receives municipally treated drinking water, which contains diverse bacterial communities that are safe for the majority of healthy individuals, but can result in severe illness in elderly and immunocompromised individuals. This research will determine the relative importance of environmental selection and dispersal limitation in shaping the bacterial communities in tap water, assess the degree to which opportunistic bacterial species are found in tap water and identify the physical, chemical and biological conditions that favor their growth in premise plumbing.


Water and biofilm samples will be collected along the drinking water flow path from the distribution system to the tap in premise plumbing (e.g., at the kitchen faucet aerator, in the hot water heater, at the showerhead). Culture-independent, next-generation DNA sequencing technology will be used to characterize the bacterial community dynamics in premise plumbing and determine under what physical and chemical conditions opportunistic bacterial groups (e.g., Pseudomonas, Mycobacterium) are found at highest abundance. Occupancy-abundance relationships will be generated to investigate whether the abundance of certain bacterial groups in premise plumbing can be explained by their abundance in the distribution system.

Expected Results:

Overnight stagnation of drinking water in premise plumbing is expected to favor the formation of bacterial communities with less diversity which will be more susceptible to invasion by opportunistic bacterial species. Plugs of drinking water that sit stagnant near flush points (e.g., faucet aerators, showerheads) and which come into contact with biofilms at the flush points will represent distinct environments that result in higher counts of opportunistic bacterial species. Locations of reduced disinfectant and higher temperature along the flow path, for example in pipes located near heating units, will result in increased counts of opportunistic bacterial species and virulence factors.

Potential to Further Environmental/Human Health Protection

More waterborne disease outbreaks in the United States are attributed to opportunistic microbes that persist and grow in premise plumbing than to pathogenic microorganisms leaving the drinking water treatment plant. Determining the conditions that favor growth of opportunistic bacteria in premise plumbing and the critical points of human exposure to opportunistic bacterial species is necessary to develop novel strategies to mitigate the risk of opportunistic bacterial infection for immunocompromised individuals.

Supplemental Keywords:

drinking water, opportunistic pathogens, premise plumbing

Progress and Final Reports:

  • 2015
  • Final