Important Tips for Minimizing Legionella Bacteria in Domestic Water Systems during times of Low Occupancy

By: Spenser Johnson, Lead Environmental Group Manager
Many industries see variations in building occupancy including but not limited to hotels, offices, condominiums, hospitals, and universities. In the US, the average hotel occupancy is about 66%. However, this can fluctuate between less than 50% to more than 75%.

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Low occupancy in buildings leaves concern for water stagnation increasing amplification of Legionella bacteria and biofilm growth throughout your domestic water system.

One of the ways that you can help prevent Legionella bacteria proliferation and the growth of biofilm is to routinely flush all outlets throughout your domestic water system. It is recommended that all outlets be flushed at least every seven days for several minutes2. This can simply be done while hotel rooms and bathrooms are being cleaned, or as part of regular maintenance. It’s important to remember that each outlet needs to be flushed regularly otherwise that section of piping can function like a dead leg in your system. In the absence of routine a water flushing protocol or for extended periods of low flow, it is important to flush outlets, consider addition of chlorine or monochloramine as a disinfection step, and validate water suitability before reintroducing the water source.

Reach out to Barclay Water Management, Inc. for more recommendations for best practice maintenance of buildings during low occupancy.


1. Rose, J. B. (2020). “Management of Legionella in Water Systems” at Retrieved from Academics of Science, Engineering and Medicine,

2. O’Donnell , J. (2009). National Guidelines for the Control of Legionellosis in Ireland, 2009. Retrieved from,3936,en.pdf

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