Are you in the planning stages of re-opening your vacated buildings?Without proper opening procedures, your buildings could be at risk of spreading Legionella Bacteria.
“While the majority of the focus for building systems seems to be air systems, lighting and space allocation, it is also important to pay careful attention to plumbing systems before re-occupying a building. Many buildings have been closed for weeks, leaving them vacant. Others are operating with few essential personnel and while the facilities have been open to these employees, the use and circulation of water in the plumbing system is much less than typical.
The water in building piping systems, water heaters, expansion tanks, pumps, etc., has been aging several weeks and residual levels of active disinfectant, if there are any, are likely below what is required. Bacteria are present in every water system, including potable water, fountains and cooling towers), and they can rapidly multiply and colonize when water is stagnant.
Furthermore, water heaters may be a breeding ground for bacteria as Legionellae flourish in hot water systems operated at temperatures below 125 degrees. Because adequate amounts of fresh water have not been introduced for many weeks, and system flow rates have likely been too low to scour the internal walls of the domestic water piping, it should be assumed that water systems need to be drained, flushed and disinfected prior to re-occupancy.
There are two sources from The American Society of Heating Refrigerating and Air Conditioning Engineers (ASHRAE) for guidelines in the safe operation and use of plumbing systems: ASHRAE Standard 188-2018 – Legionellosis: Risk Management for Building Water Systems, (and associated Addenda) and ASHRAE Guideline 12-2020 – Managing the Risk of Legionellosis Associated with Building Water Systems. Legionella pneumophila (the bacterium that causes the disease Legionellosis or Legionnaire’s Disease) is not the only waterborne pathogen known to be present in a plumbing system. Following these standards and guidelines may also reduce the risk posed by other bacteria as well. (ASHRAE publications are available for purchase from their website at this link: ASHRAE Standards and Guidelines). Please keep in mind that while draining, flushing and disinfecting your plumbing system is necessary prior to occupying a building, active mitigation of Legionella bacteria and other pathogens over the long term is necessary, even when buildings are fully occupied.
During our research and development of Preparing for the New Normal?, our initiative to provide resources for building owners and operators during the COVID-19 pandemic, we learned that a respected plumbing industry columnist and lecturer, Ron George, CPD, recently published an article available to the public that provides a step-by-step procedure for flushing your building water system. You can access that information at this link: Domestic Water Systems Flushing Procedure”
Contributors: Robert “BJ” Allen, Director of Plumbing and Fire Protection, Barton Associates.
