Grantee Research Project Results
2025 Progress Report: Consortium On Disinfection by-products and Opportunistic pathogens in Water Networks (CO-DOWN)
EPA Grant Number: R840607Title: Consortium On Disinfection by-products and Opportunistic pathogens in Water Networks (CO-DOWN)
Investigators: Kirisits, Mary Jo , Reckhow, David A. , Tobiason, John , Cambronne, Eric , Sela, Polina , Raskin, Lutgarde , Hardin, Rebecca , Shen, Yun , Kumpel, Emily , Lopes, Mariana , Vanden Heuvel, Kristan , Guikema, Seth , Impellitteri, Chris , McBeath, Sean
Institution: University of Texas at Austin , George Washington University , University of Michigan - Ann Arbor , University of Massachusetts Amherst , Water Tower , Carollo Engineers, Inc
EPA Project Officer: Harper, Jacquelyn
Project Period: August 1, 2023 through May 7, 2025
Project Period Covered by this Report: August 1, 2024 through July 31,2025
Project Amount: $2,123,000
RFA: National Priorities: Research on Disinfectants, Disinfection By-products (DBPs), and Opportunistic Pathogens in Drinking Water Distribution Systems Request for Applications (RFA) (2022) RFA Text | Recipients Lists
Research Category: Endocrine Disruptors , Harmful Algal Blooms , Drinking Water , Drinking Water, Disinfection Byproducts , Water Quality
Objective:
To reduce the overall risk to the drinking water consumer, risks associated with opportunistic pathogen (OP) exposure must be balanced with those associated with disinfection byproduct (DBP) exposure. Thus, the overarching goals of the proposed research are (i) to better understand how and why the density, type, and viability of OPs (focusing on OPs within the genus Legionella but also those among non-tuberculous mycobacteria and the genus Pseudomonas) vary in a diverse set of drinking water distribution systems (DWDSs) across the U.S., (ii) to assess how (un)regulated DBP concentrations vary among and within DWDSs, and (iii) to assess the risk trade-off to the consumer due to OPs and DBPs in DWDSs.
Progress Summary:
The CO-DOWN project aims to bring a nationwide perspective to the study of DBPs and OPs in drinking water systems. As such, one of the most important aspects of the project is to partner with a diverse range of utilities located across the United States (U.S.). The forty-four utility partners recruited for the project are located across nine of ten U.S. Environmental Protection Agency (EPA) regions and encompass a variety of system characteristics: 9% are consecutive systems, 5% are tribal systems, 36% serve less than 100,000 people, 64% serve more than 100,000 people, 52% have chloramine as the secondary residual, 48% have freechlorine as the secondary residual, 5% use chlorine dioxide, 50% use surface water only, 50% use ground water only or a blend of ground and surface water, and 39% use phosphate for corrosion control.
Alongside utility recruitment, planning and implementation of the first round of annual DWDS sampling was the primary focus of Project Year 1. The CO-DOWN team developed an EPA-approved Quality Assurance Project Plan (QAPP), as well as all of the Standard Operating Procedures (SOPs) needed to ensure standardized sampling and analyses are carried out for the annual DWDS sampling. In summer 2024, samples were collected from each utility partner’s system, including the finished-water or pointof-entry sample and at least four DWDS samples that range from low to high water ages. All samples were analyzed for total chlorine, temperature, and pH in the field and for a suite of anions in the lab. Samples from approximately one-third of utility partners were analyzed for total organic carbon, ultraviolet absorbance, and a suite of regulated and unregulated DBPs. Molecular analyses of OPs will be conducted on preserved samples at the start of project Year 2 and statistical analyses of Year 1 results will follow. The data collected to date confirm that the participating utilities encompass a wide range of water quality and system characteristics.
In addition to the first annual sampling of our partner utilities, several other sub-studies of the project were initiated in Year 1: 1) pilot operation of a biostud biofilm reactor at the University of Texas, 2) initial exploration of DBP speciation in individual DWDSs, 3) method development for evaluation of OP viability in DWDS samples, 4) method development for a combined DBP-OP risk framework, 5) method development for utility engagement in co-design of DBP/OP-related education and training content, and 6) collection of baseline data and method development of DWDS flushing as a potential DBP/OP mitigation strategy.
Future Activities:
In project Year 2, the CO-DOWN team will finish analyzing samples from the first year of DWDS sampling, send individualized progress reports of results to utility partners, host an End-of- Year 1 Project Meeting with all utility partners, continue statistical analyses of the first year’s results from the annual DWDS sampling, conduct the second year of annual DWDS sampling, and begin collecting data for the additional CO-DOWN sub-studies (biofilm formation, effect of flushing on DBPs/OPs, co-design of education and training modules).
Journal Articles:
No journal articles submitted with this report: View all 4 publications for this projectSupplemental Keywords:
biofilms, flushing program, risk management, co-learningProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.