Quantitative Performance Evaluation of Interventions for Pathogens and Chemical Contaminants in Building Water Systems: A Review and Meta-Analysis

Building water systems are associated with variable water
age and
temperatures, causing water quality concerns. Legionella spp., nontuberculous mycobacteria (NTM), and Pseudomonas spp. are known to inhabit and grow in these systems for which building-level
interventions are often required to reduce their concentrations and
detections. Other contaminants such as metals and disinfection byproducts
(DBPs) are also health concerns. Interventions are typically flushing,
temperature manipulation, responsive facility-level interventions
(e.g., chemical disinfection and heat shock), or point-of-use devices.
A systematic literature review was conducted to summarize interventions
targeting pathogen control, and subsequent meta-analysis quantified
their respective log reduction values (LRVs). Across the studies (n = 45), Legionella spp. was the primary
target (n = 45), and studies varied from laboratory
benchtops/pipe racks to hospitals and residential or commercial buildings.
Additional measurements and LRVs for heavy metals (e.g., copper, lead,
and iron) and DBPs such as trihalomethanes (THMs) were evaluated.
The findings pointed to the importance of contextual conditions and
incoming water quality in playing a role in both pathogen occurrence
and intervention effectiveness. Common interventions such as recommissioning
flushing and increased temperature should be further examined for
their impacts on pathogens besides Legionella spp.
and their contribution to biofilm sloughing and pathogen regrowth.
Trade-offs, such as increased metal leaching in parallel with pathogen
inactivation, should be examined in context with intervention and
building water quality conditions.