Grantee Research Project Results
2019 Progress Report: Water Conservation and Water Quality: Understanding the Impacts of New Technologies and New Operational Strategies
EPA Grant Number: R836880Title: Water Conservation and Water Quality: Understanding the Impacts of New Technologies and New Operational Strategies
Investigators: Gurian, Patrick , Olson, Mira S. , Haas, Charles N. , Summers, R. Scott , Clancy, Jennifer , Masters, Sheldon , Bartrand, Tim , Duarte Batista, Marylia , Joshi, Sayalee , Hamilton, Kerry , McCuin, Randi , Rasheduzzaman, MD , Singh, Rajveer , Seidel, Chad , Tolofari, Dienye L , Yang, Zhao , Young, Audrey , Yu, Yun
Current Investigators: Gurian, Patrick , Olson, Mira S. , Haas, Charles N. , Summers, R. Scott , Clancy, Jennifer , Masters, Sheldon , Treado, Steven
Institution: Drexel University , Arizona State University , Environmental Science Policy and Research Institute , University of Colorado at Boulder
Current Institution: Drexel University , Pennsylvania State University , University of Colorado at Boulder
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 2016 through September 30, 2019 (Extended to September 30, 2021)
Project Period Covered by this Report: October 1, 2018 through September 30,2019
Project Amount: $1,989,000
RFA: National Priorities: Impacts of Water Conservation on Water Quality in Premise Plumbing and Water Distribution Systems (2016) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Climate Change , Water
Objective:
The project combines literature information with novel experimental results to develop and validate predictive models of the risk of failing to meet water quality goals for premise plumbing. The models will be encoded in a web-based decision support tool usable by facilities managers and utility personnel to identify high risk conditions for premise plumbing water quality and potential remedial actions.
Progress Summary:
The research efforts of the project team are divided into the following four broad tasks:
- Task 1: QMRA informed water quality standards for built environments: Setting critical acceptable concentrations for OPPPs in built environments
- Task 2: Water conservation impacts on water quality: Expert consultations, literature review, and modeling approaches
- Task 3: Water quality in premise plumbing: Pipe rack and hot water experimental set ups
- Task 4: Development of a decision support tool
A summary of the key accomplishments for each research task are given below.
Task 1 focused on setting threshold concentrations for various Opportunistic Premise Plumbing Pathogens (OPPPs) in different built environments exposure scenarios for health-based water quality target concentrations using Quantitative Microbial Risk Assessment (QMRA) approach. Models were developed for calculating risk-based critical concentrations of Legionella pneumophila for indoor residential water uses on a per fixture exposure and aggregate (multiple fixture) exposure basis. A peer-reviewed manuscript based on this study was published in Environmental Science and Technology that appeared on the cover page of the April 2019 issue of the journal. Similar QMRA target risk-based models were developed to calculate acceptable concentrations of Pseudomonas Aeruginosa for the eye infection through contact lenses contamination exposure scenario and Naegleria Fowleri exposure through swimming and nasal cleaning (via the use of a neti potTM or similar device). A peer-reviewed manuscript based on this study was published in the journal Water. In yet another similar study, numeric critical concentration guidance values are being developed for Mycobacterium avium complex (MAC), a subset of nontuberculous mycobacteria (NTM), using target risk based QMRA approach for a set of exemplary exposure scenarios in building environments. A manuscript based on this study is in advance draft stage to be submitted to Water Research.
Under Task 2, the first set of subtasks are focused on identifying appropriate management strategies and knowledge gaps in maintaining water quality in premise plumbing though consultation/semi-structured interviews of subject matter experts (SMEs) and facility managers (FMs), review of existing guidance information (GDs), DELPHI approach, and water residence modeling in premise plumbing. A manuscript based on 22 SME consultations and 15 systematically identified GDs is currently in the 2nd round of peer review at the journal Water. The manuscript identifies 18 design and 11 operational issues of critical concern for managing water quality in buildings and 11 knowledge gaps. The research team has compiled a database of guidance for existing water quality management practices in buildings that includes parameters such as water heater setpoint temperature, allowable time for hot water to reach the tap, and monitoring parameters. A Delphi approach- a structured method of multiple rounds of experts' panel consultation for quantitative forecasting of viable solution where enough data is missing or incomplete- is being explored as a method to develop consensus guidance for water quality management in buildings. In yet another effort on water quality management in buildings, a modeling approach is being developed for calculating water residence time in premise plumbing based on two data sources; (1) literature data on water usage pattern in different plumbing fixtures in the buildings and (2) experimental data on residual decay in various sizes and materials plumbing collected in-house in the experimental section of this project described in the Task 3 section below.
The second set of subtasks under Task 2 are focused on compiling literature based evidence for water quality management in building through systematic literature review and meta-analysis. In one such effort, specifically focused on hotels buildings, we investigated the required water heater setpoint temperature for controlling Legionella Spp. growth in hotel plumbing systems. Systematic literature review and meta-analysis of the data associated with water temperature and Legionella colonization in premise plumbing revealed that a water heater setpoint temperature between 60-64 0C is required for achieving non-detectable levels of Legionella with high confidence in hotel plumbing systems. A manuscript draft based on this study is ready to be submitted to the journal Environmental Research. A second study under this subcategory was focused on developing a framework for disinfection byproducts (DBPs) formation in premise plumbing through systematic literature review and meta-analysis. Preliminary investigation in this study based on raw data from 17 studies (after reviewing 51 articles) show that residual free Cl2, TOC, and pH-allows reasonable prediction (R2=0.897) of DBPs (such as haloacetic acids). A third study is being conducted to investigate effectiveness of free chlorine and chloramine for control of Mycobacterium and Legionella in premise plumbing system based on systematic literature review and meta-analysis. A systematic literature search strategy using the PRISMA framework was applied to narrow down 210 research article to 8 research articles that provided relevant data for the meta-analysis.
Task 3 focused on experimental data collection and analyses for both chemical (mostly DBPs formation) and biological (i.e., various OPPPs growth) water quality assessment in simulated cold and hot water premise plumbing experimental systems. The details of these simulated systems are reported in the Year 2 progress report. Briefly, cold water building plumbing systems were simulated in duplicate pipe loop experiment set ups each consisting of 24 pipes in Philadelphia, PA (chloramine as disinfectant residual) and Boulder, CO (free chlorine residual). A duplicate full factorial experimental design with factors being two pipe diameters (1/2" and 3/4"), three pipe materials (copper, PEX, and PVC), and two usage frequencies (twice per day and once per week) were investigated at each location. The hot water systems were also conducted in duplicate at both PA and CO locations with each location consists of 4 tanked heaters simulating water heaters used by residential consumers. Four tanks were operated at two water use patterns (a high use, twice per day, and a low use, once per week) and two temperature settings (a low temperature 48 0C target and a high temperature 60 0C target).
Multiple analyses are underway for the data collected from the cold water pipe loops experimental set ups to understand the impact of the three experimental factors, i.e. pipe diameter, pipe material, and usage frequency. A longitudinal data analysis was conducted to investigate the overall impact of the three factors on water quality deterioration in terms of loss of residual concentration, formation of TOC, and nitrification in the premise plumbing systems. Similarly, another analysis of experimental data was focused on investigating the impact of the factors on the DBPs formation. Yet another analysis is focused on evaluating the microbial water quality aspect, specifically mycobacteria dynamics, with respect to the three experimental factors. Three peer review manuscript drafts each based on these three analyses separately are under internal review among the co-authors and are expected to be submitted to Water Research, Science of the Total Environment, and Risk Analysis, respectively. The data from the water heater experiments is currently being analyzed to evaluate the effect of water heater experimental conditions (i.e., temperature and usage patterns) on water quality in terms of loss of residual disinfectant, growth of OPPPs, and disinfection byproducts (DBPs) formation.
For Task 4, a database summarizing the influence of various design and operational factors on water quality in premise plumbing has been built from review of 54 guidance documents from regulatory agencies from US and worldwide and consultation of 22 subject matter experts and 15 facility managers. Further consultations with facility managers and experts (via Delphi approach) are currently underway. This database will be used for building the online decision support tool. Efforts are also underway to build a decision support tool for water quality management that will be based on the water residence time and residual decay models as described in Task 2 above.
Overall the project has produced seven peer reviewed manuscripts that are either published, submitted, or in the advanced stage of review. We have also presented 23 conference abstracts at various nation/international conferences including AWWA, AEESP, and SRA. Patrick Gurian and Rajveer Singh are also serving are guest editor for a special issue, "Building Water Quality" in the journal Water.
Future Activities:
Some of the key activities for Year 4 include complete meta-analysis of the literature data, complete baseline models for residence time and chloramine decay in premise plumbing, field sampling at three selected locations; finish conducting facility managers' interviews, and build the decision support tool.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 42 publications | 7 publications in selected types | All 7 journal articles |
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Type | Citation | ||
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Rasheduzzaman M, Singh R, Haas CN, Tolofari D, Yassaghi H, Hamilton KA, Yang Z, Gurian PL. Reverse QMRA as a decision support tool:setting acceptable concentration limits for Pseudomonas aeruginosa and Naegleria fowleri. Water 2019;11(9):1850. |
R836880 (2019) R836880 (2020) R836880 (Final) |
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Hamilton KA, Hamilton MT, Johnson W, Jjemba P, Bukhari Z, LeChevallier M, Haas CN, Gurian PL. Risk-based critical doncentrations of Legionella pneumophila for indoor residential water uses. Environmental Science & Technology 2019;53(8):4528-4541. |
R836880 (2019) R836880 (2020) R836880 (Final) |
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Supplemental Keywords:
Opportunistic premise plumbing pathogens (OPPPs), Reverse quantitative microbial risk assessment (QMRA), Legionella pneumophila, Building water quality, Green buildings, Efficient water fixtures, Premise plumbing, Disinfection residuals, Disinfection byproductsRelevant Websites:
Progress 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.