Seyfarth Synopsis: CDC explains that the shutdown or reduced operation of a building and reductions in normal water use can create hazards for returning occupants. It recommends in its updated Guidance for Reopening Buildings that building owner-operators check for hazards before reopening. Hazards may include lead and copper contamination, mold, and Legionella (the cause of Legionnaires’ disease).

Earlier this year, CDC released guidance for reopening buildings that discussed the potential hazards created by Legionella in water systems. In this update, the CDC adds guidance for addressing lead and copper that may be introduced into building water systems that have had low or no use for a prolonged period of time. Depending on the particular water system, “prolonged period” could mean weeks or months, or potentially even days of reduced usage. CDC also adds guidance for mold awareness, monitoring, and remediation during and after prolonged building shutdowns; updates the Legionella guidance for people with weakened immune systems, and recommends the use of respiratory protection when flushing water systems.

For lead and copper, the CDC indicates that a prolonged shutdown may affect systems depending upon the amount of time water remains stagnant inside the pipes, whether there are protective scales or coatings present inside pipes that prevent metals from leaching into water, and the materials used to build the plumbing system.

For mold, a prolonged shutdown may affect buildings depending upon building-specific factors such as ventilation, water intrusion, and construction, as well as seasonal and weather variables.

For Legionella, the potential for introduction into the water system depends upon the amount of time the system was shut down, plumbing-specific factors such as low points or areas prone to becoming stagnant, disinfectant residuals, water heater temperature set points, water usage patterns, and preexisting Legionella colonization.

For lead, coper, and Legionella, CDC recommends regular maintenance of water systems, even when buildings are not occupied or have low occupancy, as well as regular flushing and testing of systems for lead, copper, and Legionella. For mold, CDC recommends maintaining indoor humidity below 50% at all times, including while a building is unoccupied, as well as assessing a building for mold and excess moisture and “flushing out” the building HVAC system prior to building occupancy.