inhale shower lab

INvestigating Home water and Aerosols’ Links to opportunistic pathogen Exposure

Video explaining the focus of the Haig INHALE lab

Why do we need a shower lab? As people take showers, they are exposed to billions of bacterial cells through contact with the water and inhalation of produced aerosols. While many of these organisms are harmless, some drinking water-associated pathogens (DWPIs) are a leading cause of serious health risks, especially for individuals with weakened immune systems (e.g., elderly people, people with pre-existing health conditions. Although there are more significant sources of DWPI exposure such as contaminated cooling towers, it is hard for at-risk people to employ mitigation techniques for these larger sources. Researching ways to reduce DWPIs in both shower water and shower associated aerosols can help empower people to lower their risk of DWPI infection in their homes. 

The Facility: The Haig INHALE lab consists of three identical shower stalls that each contain 3 showerheads. This allows for the collection of replicate sample sets in the same environment. Each stall is supplied with hot water from its own water heater which allows for additional experimentation on the effects water heater setpoint has on DWPI population.  


Studies happening:

1. Looking for the silver lining: Assessing the impact of silver in showerheads on opportunistic pathogen abundance and resistance (funded by NSF: CBET-1935378)

  • Personnel associated with the project: Sarah Pitell, Evan Trump, Paige Moncure, Jaime Mastropietro, Danny Huffman, Krystolynn Harris, Leanne Gilbertson, Jill Millstone, Janet Stout, and Sarah Haig

  • Summary & Aims: This study assessed the material effects of silver, a common antimicrobial, on the living microorganisms present in shower water, with a focus on public health- relevant microorganisms in a multi-disciplinary approach. Silver-containing point of use fixtures are being increasingly marketed to vulnerable populations, so validating their efficacy and potential unintended effects is critical for consumers to make informed decisions in their environments. 

  • The aims of the study were to: 

  • Quantify and characterize viable potential respiratory pathogens of public health concern in shower water. 

  • Determine the impact that silver-containing showerhead have on water chemistry and the microbiome 

2. INvestigating Home water and Aerosols' Links to opportunistic pathogen Exposure (INHALE): do consumer decisions impact pathogen exposure and virulence? (funded by NSF: CBET-2326096)

  • Personnel associated with the project: Mariia Nikitina, Cheolwoon Woo, Janet Lee, and Sarah Haig

  • Summary & Aims: The long-term goals of this study are to quantitively assess the DWPI exposure risk posed by aerosols produced by different showerhead setups and ascertain if different setups select for greater DWPI exposure and more virulent DWPIs. This goal will be achieved through two research objectives. Objective 1 will test a range of different showerhead setups in an experimental shower lab and quantify the abundance of live L. pneumophila, P. aeruginosa, and NTM in shower water and its associated aerosols using ddPCR and develop shower water to aerosol partitioning models for each DWPI and showerhead. Objective 2 will use a combination of genomic, kinetic, biofilm aggregation, and macrophage infectivity assays to investigate the role that showerhead setup has on organism fitness and virulence. The successful completion of this research has the potential for transformative impact through the generation of new data and fundamental knowledge including mechanistic models of exposure and risk to human health related to the presence of DWPIs in shower water and shower water produced aerosols.

Past studies:

  1. A breath of fresh air - Evaluation of the impacts antimicrobial showerheads have on the water and aerosol microbiomes (funded by A University of Pittsburgh Central Research Development Fund)

  • Summary & Aims: This study was focused on characterizing how the microbial community was affected in both shower water and shower water-associated aerosols when using commercially available showerheads marketed to have anti-microbial properties. 

For details of the results please read - Assessing the impact of anti-microbial showerheads on the prevalence and abundance of opportunistic pathogens in shower water and shower water-associated aerosols

2. Observing drinking water-associated opportunistic pathogen abundance from a model shower system after the Covid-19 shutdown 

  • Summary & Aims: This study explored the impacts of extended stagnation caused by the Covid-19 building shutdowns had on the chemical and microbial drinking water quality, and the efficacy of common flushing regimes meant to reduce its effects. Extended water age has been linked to worse water quality, but the effects of extreme stagnation have been understudied. Also, common interventions to combat stagnation such as opening outlets for a set period and allowing water to flow have been widely suggested to building managers, but the efficacy of these flushing regimes has not been fully characterized. Determining how extended periods of water stagnation affects chemical and microbial water quality and how effective mitigation strategies are can assist building managers in making decisions in periods of reduced water usage. 

    For details of the results please read - Legionella pneumophila occurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

3. Save It, Don't Spray It: Do water saving showerheads impact the microbes we breathe in during showering? (funded in part by a University of Pittsburgh MCSI summer grant)

  • Summary & Aims: This study investigated the effects of water-conserving showerheads on the physical, chemical, and biological characteristics of shower water and shower-water associated aerosols. As water scarcity becomes an even greater threat around the world, water-saving strategies are becoming increasingly important. “Green” technologies such as showerheads that use less water to operate are a popular solution to reducing water use, however lowering flow in plumbing systems to cause stagnation has been linked to higher microbial loads in drinking water. Understanding how showerhead flow rates influence aerosol transport and microbial dynamics can ensure that consumers are weighing all the factors associated with adopting these types of fixtures. 

  • Papers in prep, but checkout the video

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