Suchergebnisse

AbstractThe residence time of water in residential building water systems is a critical factor regarding water quality at end use. Published literature has highlighted the importance of water age in these systems and its relationship with pathogenic bacteria such as Legionella pneumophila. However, tools to measure water age in such plumbing systems are typically repurposed from other applications and include limitations that make them inappropriate for some plumbing systems. This work presents a novel means of estimating water age by assuming these systems operate without mixing. Data for this study was collected from a full‐scale home equipped with an extensive array of flow meters to monitor water use. Further, 408 individual water quality samples were collected to ascertain water quality changes that take place in the plumbing. Model results show weak correlation with EPANET 2.2 (ρ = 0.666), a commonly used hydraulic modeling software. The results of the water age model were also evaluated with several variable selection tools. These analyses indicate that this method's water age results are a statistically significant (p < .05) predictor of Legionella concentrations. Model results from this approach could be used in plumbing design and/or operation to assist in managing Legionella risks.

AbstractOpportunistic pathogens, such as several species of Legionella, are a growing concern globally. This is especially true in building plumbing. Plumbing design guidance has not been updated to reflect changes in use, leading to increased hydraulic retention time and exacerbating pathogen risks. While the effects of several water quality variables on Legionella spp. concentrations are well‐studied at bench‐scale, little is known about the strength of, or interactions between, these relationships in full‐scale plumbing. The influence of water quality variables and water use metrics on Legionella spp. concentrations was evaluated with several statistical tools from a data‐driven perspective. The results add to the weight of evidence required to develop systematic risk management strategies like monitoring. Variables related to Legionella and logistically more feasible to measure in full scale buildings, such as dissolved oxygen, heterotrophic plate count, total organic carbon, and water age, were identified.

AbstractSustainability, water conservation, water efficiency, and green infrastructure have led to significant decreases in the quantity of water used in buildings. In addition, changes in water usage, building design, plumbing material selection, and high‐efficiency fixtures contribute to water age and potential chemical and microbiological contamination. Through a literature review and stakeholder workshop with representatives from the public and private sectors, this article explores the current state of the science on plumbing safety. Results indicate that links between water usage, design, and material selection and water quality must be established with data‐driven methods to support risk assessment and risk management decisions. Of particular interest is a better understanding of the contribution of water usage and piping materials to the proliferation of opportunistic pathogens. This article will help further efforts to evaluate these pathogenic risks, a critical need as drinking water regulations have primarily focused on exposure through ingestion.