Grantee Research Project Results
Final 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 , Treado, Steven
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 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 combined literature information, structured consultations with experts and building facility managers, meta-analyses, and novel experimental results to strengthen the knowledge base for protecting water quality in premise plumbing. The knowledge developed is encoded in a web-based decision support tool- the Plumbing Information and Performance Evaluation (PIPE) decision support tool. PIPE can be used by building facilities managers to identify concerns regarding premise plumbing water quality and potential remedial actions. Another decision support tool has been developed to identify the probability with which residual disinfectant would be maintained in a household cold water plumbing system given typical water usage patterns and specified residual decay rates to support the selection of appropriate pipe sizes and materials.
Summary/Accomplishments (Outputs/Outcomes):
The research undertaken during this project period identified significant challenges to human health in the manner in which many building water systems are operated. These systems were found to frequently be operated at temperatures favorable to the growth of Legionella and other opportunistic pathogens. The research also identified options for control of opportunistic pathogens that are feasible and cost-effective, including specific guidance for water heater setpoints, disinfectant residual concentrations, and the appropriate use of thermostatic mixing valves. Quantitative microbial risk assessment methods were applied to improve understanding of the concentrations of opportunistic pathogens (Legionella, Naegleria fowleri, Pseudomonas aeruginosa, and mycobacteria) that exceed commonly accepted benchmarks of acceptable risk. This can guide decision making regarding when risk mitigation is required for these organisms. The summary of the key accomplishments is divided into four broad categories as described below:
Task 1: Risk informed water quality analyses in built environments: Analyses of critical acceptable concentrations for OPPPs and chemical risk in building plumbing systems
Task 1 focused on setting threshold concentrations for various Opportunistic Premise Plumbing Pathogens (OPPPs) in different built environment 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 (Hamilton et al., 2019). 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 pot™ or similar device) (Raheduzzaman et al., 2019). We further leveraged efforts by Dr. Hamilton’s lab at Arizona State University and collaborated with her on developing similar QMRA models to determine critical concentrations of 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 soon to be submitted to Water Research for peer-review publication (Joshi et al., 20xx). Another risk-based study compared microbial (Mycobacterium avium) and chemical (various disinfection by-products) risks of water quality in building plumbing systems using the Disability Adjusted Life Years (DAILY) approach. A manuscript based on this study is soon to be submitted for peer-review publication (Tolofari et al., 20xx).
Task 2: Water quality issues and their management in building plumbing systems: Expert consultations, literature knowledge synthesis, and meta-analyses
Under Task 2, the first set of subtasks focused on identifying appropriate management strategies and knowledge gaps in maintaining water quality in building plumbing systems. Semi-structured and structured interviews were conducted with subject matter experts (both researchers and practitioners) and building owners and facility managers (FMs) along with a review of guidance documents (GDs) for knowledge synthesis, and a Delphi panel was conducted for assessing consensus among experts’ knowledge. In one study, 22 Subject Matter Experts (SMEs) were consulted and 15 systematically identified GDs were reviewed to identify the issues and knowledge gaps in building water quality management. The study identified 18 design and 11 operational issues of critical concern for managing water quality in buildings and 11 knowledge gaps (Singh et al. 2020). The research team compiled a database of guidance for existing water quality management practices in buildings that was subsequently used for developing a decision support tool to help building owners and facility managers (Task 4). Further, to understand realistic ground situation among practitioners on water quality management practices prevalent in buildings in the United States, building facility manager interviews were conducted. Semi-structured phone surveys and structured online surveys were conducted with 41 building facility managers about building plumbing system management practices in their buildings. The aim of this study was to compare the existing management practices with the available guidance and identify the potential problematic spots in their buildings. A manuscript based on this study is currently under peer-review in the journal Water (Singh et al., 20xx). Lastly, a literature engaged Delphi study- consisting of two rounds of expert surveys- on building water quality management issues was conducted to achieve consensus among various experts’ views and identify differences at the same time. A questionnaire on building water quality issues was developed after iterative consultation with an internal group of experts. A diverse group of 104 external experts were selected for participation in this study of which a total 35 responses in the 1st round and 25 responses in the 2nd round were elicited, of which xx% and xx% consensus levels were achieved in 1st and 2nd rounds, respectively. This study constitutes a thesis chapter in Rasheduzzaman (2021) and a manuscript based on this study will be submitted for peer-review publication (Rasheduzzaman et al., 20xx).
Another set of subtasks under Task 2 are focused on compiling evidence for water quality management in buildings through systematic literature reviews and meta-analyses. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework was used for all studies in this subtask for the identification and screening of literature documents for the relevancy to a particular study. One such effort conducted a systematic review of outbreaks of Legionnaires Disease and Pontiac Fever between 2006-2017. The study analyzed a total 136 outbreaks and found cooling towers responsible for large portions of the outbreaks while building water systems and pools/spas were also found responsible for many outbreaks (Hamilton et al., 2018). Another similar effort focused on investigating hot water temperature and Legionella colonization in hotel plumbing systems to optimize temperature control of Legionella. Qualitative synthesis and quantitative analysis were performed on 13 studies identified from the literature by systematic search. The analyses identified 55 0C as a cutoff point for plumbing hot water temperature and found a strong negative association between temperature and Legionella colonization. A logistic regression analysis of hot water temperature and Legionella detection found a temperature of 59 0C associated with an 8% probability of detectable Legionella (Rasheduzzaman et al. 2020). Similarly, a systematic literature review and meta-analysis study was performed to identify the effectiveness of free chlorine and chloramine disinfectants for controlling Legionella in premise plumbing systems. The effort identified 29 literature studies and found 0.2 mg/L and 2.5 mg/L as effective concentrations of free chlorine and chloramine, respectively, for Legionella control. This study constitutes a thesis chapter in Rasheduzzaman (2021) and a manuscript based on this study will be submitted for peer-review publication (Rasheduzzaman et al., 20xx).
Task 3: Experimental investigation of chemical and microbial water quality issues in cold and hot water building plumbing systems
Task 3 focused on experimental investigations of the different issues related to water quality in building plumbing systems, viz, residual decay, microbial growth, and DBPs formation. Duplicate experimental set ups simulating cold water plumbing systems in buildings (pipe racks) and hot water systems (water heater tanks) were set-up in Philadelphia, PA (chloramine disinfectant) and Boulder, CO (free chlorine disinfectant). Each cold-water pipe rack experimental system consisted of a duplicate 2x3x2 full factorial experimental design with factors being two pipe diameters (1/2” and ¾”), three pipe materials (copper, PEX, and PVC), and two usage frequencies (twice per day-high use and once per week-low use). Each hot water system consisted of 4-tanked heaters simulating water heaters used by residential consumers. The different tanks were operated at two water use patterns (a high use, three times per day, and a low use, once per day) and two temperature settings (a low temperature 45 ± 3 0C and a high temperature 60 ± 3 0C).
First, a full factorial study of pipe characteristics (material and diameter) and stagnation time on residual decay in free chlorine and chloramine pipe rack systems was conducted. Copper pipes consumed more residual than other plastic pipes and so did the smaller pipes in chloramine systems. Nitrification was observed for as low as a 12-hour stagnation period (Tolofari et al., 2020). A study on OPPPs growth in cold pipe rack experiments showed no mycobacteria detection in the free chlorine pipe rack system (i.e., Boulder, CO set up). For the chloramine system (i.e., Philadelphia, PA set up) high use pipes showed faster colonization and growth of mycobacteria as compared to the low use pipes. Only usage frequency seems to impact microbial density; pipe material and diameter do not appear to impact occurrence and growth of mycobacteria. Another study on DBP formation in cold-pipe racks showed type of disinfectant and use frequency impacted Total Trihalomethane (TTHM) and sum of five haloacetic acids (HAA5) in the racks while the effects of pipe diameter and pipe material were not significant. Free chlorine degraded rapidly for the free chlorine system, and DBP formation was chlorine limited. Monochloramine was more persistent than free chlorine but still was not present in any samples after one week’s stagnation. TTHM or HAA5 in both pipe rack set ups never exceeded US EPA regulatory limits of 80 μg/L and 60 μg/L, respectively.
For studies focused on hot water heater tank experiments, one study focused on investigating the influence of hot water temperature and use patterns on microbial quality. Microbial analyses were conducted on water samples collected at the tank effluent and the shower head to compare the water quality in the tank before the stagnation period and in the piping downstream of the tank after the stagnation period. The results indicated that culturable NTM was not detected under any of the conditions studied in the free chlorine disinfectant system. In the chloramine system, higher water use frequency (equivalent to 180 gallons/day) and higher water heater temperature (60 0C ± 3 0C) decreased the number of heterotrophic bacteria in the tank and the piping downstream to the tank but failed to control NTM. For both heterotrophic plate count and NTM, the piping downstream was not more microbially active than the tank (Tolofari et al., 2021). Another study on DBP formation in hot water systems showed that the water use pattern impacted DBP formation more than temperature settings. In the free chlorine system, free chlorine concentrations decayed below the detection limit within three hours. The concentrations of the regulated DBPs, trihalomethanes (TTHMs) and five haloacetic acids (HAA5), as well as nine haloacetic acids (HAA9), were about two times higher at the hot water point of use than the cold feed water into the system. On the other hand, in the chloramine system total chlorine was detectable at the hot water point of use under all conditions and no significant change in regulated DBPs formation was observed from cold water feed into the tank to the hot water point of use. Haloacetonitriles (HAN4) were observed to decrease in both systems possibly due to thermal decomposition (Batista, M. D., 2020).
Task 4: Development of a decision support tools to help building water management practitioners manage water quality in their buildings.
For Task 4, a database of the factors influencing water quality in buildings was built from a review of guidance documents from regulatory agencies from US and worldwide and structured and semi-structured interviews/surveys with 22 subject matter experts, 41 facility managers, and a Delphi panel of 35 experts. This database has been used for developing an online decision support tool to help building owners and facility managers in their building water quality management. The tool allows users to input their building specific information and outputs tailored guidance information on water quality and suggests potential remedial actions.
In another similar effort a decision support tool is being developed to help select plumbing design (pipe diameter and material) and fixture types (conventional and water efficient) for single family homes as well as risk analysis of implementation of water conservation plans for single family homes. The tool is based on modeling water residence time and residual decay with consideration for fixture flow rates, pipe diameter and materials, and usage behaviors of the residents.
Journal Articles on this Report : 7 Displayed | Download in RIS Format
Other project views: | All 42 publications | 7 publications in selected types | All 7 journal articles |
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Hamilton KA, Prussin AJ, Ahmed W, Haas CN. Outbreaks of legionnaires’ disease and pontiac fever 2006–2017. Current environmental health reports 2018;5(2):263-71. |
R836880 (2020) R836880 (Final) |
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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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Tolofari DL, Masters SV, Bartrand T, Hamilton KA, Haas CN, Olson M, Summers RS, Rasheduzzaman M, Young A, Singh R, Gurian PL. Full factorial study of pipe characteristics, stagnation times, and water quality. AWWA Water Science 2020;2(5):e1204. |
R836880 (2020) R836880 (Final) |
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Singh R, Hamilton KA, Rasheduzzaman M, Yang Z, Kar S, Fasnacht A, Masters SV, Gurian PL. Managing Water Quality in Premise Plumbing:Subject Matter Experts’ Perspectives and a Systematic Review of Guidance Documents. Water 2020;12(2):347. |
R836880 (2020) R836880 (Final) |
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Tolofari DL, Bartrand T, Masters SV, Duarte Batista M, Haas CN, Olson M, Gurian PL. Influence of Hot Water Temperature and Use Patterns on Microbial Water Quality in Building Plumbing Systems. Environmental Engineering Science 2021. |
R836880 (Final) |
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Rasheduzzaman M, Singh R, Haas CN, Gurian PL. Required water temperature in hotel plumbing to control Legionella growth. Water Research 2020:115943. |
R836880 (2020) R836880 (Final) |
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Supplemental Keywords:
Opportunistic premise plumbing pathogens (OPPPs); Quantitative microbial risk assessment (QMRA); Legionella pneumophila; Building water quality; Green buildings; Efficient water fixtures, Premise plumbing, Disinfection residuals, Disinfection byproducts; Decision Support Tool
Relevant Websites:
The Decision Support Tool Exit , Progress and publications Exit
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.
Project Research Results
- 2020 Progress Report
- 2019 Progress Report
- 2018 Progress Report
- 2017 Progress Report
- Original Abstract
7 journal articles for this project