Managing water quality in premise plumbing: application of systematic review, meta-analysis, and the Delphi method for decision making

Md Rasheduzzaman

doi:10.17918/00000580

Managing water quality in premise plumbing systems, such as water systems in hotels, apartment buildings, and hospitals, is complex and often requires expenses to protect public health. Opportunistic premise plumbing pathogens (OPPPs) such as Pseudomonas aeruginosa, Mycobacterium avium, and Legionella pneumophila are responsible for a large number of infections and the reported infections are increasing significantly day by day. Nearly 40,000 hospitalizations per year have been reported in the United States, and the cost of treatment for the relevant diseases exceeds $900 million. This thesis work focused on addressing water quality issues in building water systems and providing sustainable solutions to manage the risk of waterborne pathogens. A lack of consensus on current measures and their appropriate application to control these OPPPs is present in the existing literature and guidance documents, which indicates a need for more evidence-based research. To address water quality issues in building water systems, several research efforts have been conducted in this dissertation which include (i) compiling a database for water quality assessment and management through guidance document review and subject matter expert (SMEs) based interviews, (ii) identifying critical operational factors and their appropriate levels to reduce the risk of microbial contamination, iii) performing systematic reviews and meta-analyses of the available evidence to identify the required water temperature, the effective disinfectant and corresponding residual disinfectant levels for effective remediation and control of OPPPs v) eliciting experts' knowledge through implementing a Delphi study to identify control measures for the knowledge gaps and areas of disagreement in managing water quality and to develop best practice guidance based on a consensus of the experts. This thesis is divided into six chapters. Chapter 1 provides general background and current state of the literature knowledge on the water quality issues in building plumbing systems and lays out the specific objectives for this thesis. Chapter 2 identified 11 operational topics as critical for managing water quality in buildings. No one guidance document addressed all these topics, suggesting that a compendium of available guidance is needed. SMEs most frequently recommended temperature and residual disinfectant measurements as good parameters for monitoring overall building water quality. In Chapter 3, qualitative synthesis and quantitative analysis were performed on 13 studies that met our inclusion criteria to identify the effect of temperature on Legionella colonization. Both qualitative synthesis and meta-analyses of the data collected indicated maintaining temperatures ranging from 55°C to 59°C as the required hot water temperature to control Legionella in premise plumbing systems. Similar analyses for residual type and concentration in Chapter 4 identified chlorine as more effective against Legionella than chloramine and found risk-based required residual concentration levels for both chlorine and chloramine. Chapter 5 conducted a modified literature-engaged Delphi study, which identified areas where consensus on water quality management issues in buildings has not been achieved (e.g., disinfectant residual levels, flushing frequency, etc.). The study is useful in guiding future efforts to develop a better-shared knowledge base on these topics. Chapter 6 summarizes key findings and broader implications of the results of this dissertation. The findings will not only provide guidance for stakeholders to manage their building water systems but also add significantly to the knowledge base for providing clean drinking water and protecting public health.

Managing water quality in premise plumbing: application of systematic review, meta-analysis, and the Delphi method for decision making

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Managing water quality in premise plumbing: application of systematic review, meta-analysis, and the Delphi method for decision making

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