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Don’t Let Your Building’s Water Become Stagnant


Nephros, Inc., a commercial-stage company that develops and sells high-performance water purification products and pathogen detection systems to the medical and commercial markets, announced the results of a study this summer of water safety issues in light of the COVID-19-related nationwide shutdown.

As further described in a new academic paper available on the biology preprint site bioRxiv, from Cold Spring Harbor Laboratory, Nephros collected and analyzed 88 water samples from a variety of occupied and unoccupied buildings, using its SequaPath pathogen detection system. Key takeaways from the study include:

  • Bacterial counts in unoccupied, underused building plumbing systems were significantly higher—between 1.4 and 1,400 times higher—than levels found in buildings with normal occupancy and water usage.
  • More than 50 highly pathogenic (i.e., disease-causing) bacteria were detected in approximately 60 percent of unoccupied building samples, compared with 35 percent in occupied building samples.
  • Many of the pathogens detected are not typically included in commercial water testing products. Indeed, Legionella, the bacteria most tested for, was found in only about 10 percent of the samples in the study.

“As our lives return to normalcy, health and safety is surely the number one priority for building managers,” commented Kimothy Smith, PhD, DVM, VP of Pathogen Detection Systems of Nephros and lead author of the white paper. “Unfortunately, as this study shows, following this long, truly unprecedented period of under-use, water systems in the bulk of under-occupied buildings across the country may pose real health risks for occupants, including from pathogens not included in most commercial water testing products. This study highlights the need for truly broad-based water testing, to prevent people from contracting new illnesses from their workplace water.”

Chlorine Loses Effectiveness in Under-used Buildings

Most office buildings and many other facilities across the country have been unoccupied and under-used during the COVID-19 pandemic. When buildings are unoccupied, water in building piping systems becomes stagnant. The basal levels of chlorine, a disinfectant, decrease over time in such stagnant water. Under such conditions, bacteria tend to accumulate quickly in building piping systems.

Daron Evans, President and CEO of Nephros commented, “Standard testing guidance for bacteria in building water systems generally focuses on Legionella. As the world shifts to its new normal and buildings are re-occupied, this study highlights the critical need to expand testing to include a broad array of water-borne pathogens, not just Legionella. Nephros’ SequaPath system, which will be available soon as a service provided by Nephros, will be able to identify over 20,000 different bacterial families in real-time, to provide the broadest possible assessment of premise plumbing bacteria. Once building engineers understand their building’s unique bacterial census, they will be able to design their own custom PluraPath assay to monitor remediation progress in real-time, if needed.”

Many of the detected pathogens are on the Centers for Disease Control & Prevention (CDC) list of Opportunistic Pathogens of Premise Plumbing.