Government centers, shopping malls, schools, sports arenas and other venues shuttered due to the COVID-19 lockdowns require extra precaution when reopening to protect building water health. The sudden and prolonged closures during the pandemic may have resulted in water system conditions that can increase Legionella, which could lead to Legionnaires’ disease and other microbiological amplification and water quality concerns, including corrosion and lead accumulation.

Checked by NSF is a new global program that assists in the reopening of facilities while minimizing risk for customers, guests and employees. A healthy building water system is an important focus of the Checked by NSF program, which was developed in response to restaurants, hotels, retailers, museums and airlines across the globe who asked for advice and assistance with reopening plans. 

Checked by NSF helps organizations operationalize and apply public health guidance to their specific situations, as well as ensures appropriate preventive measures are in place and provides valuable data about preparedness. The new program also helps organizations build trust with staff, customers and the community by addressing uncertainties of planning for the new normal of a COVID-19 world.

A three-phased approach involves tasks, procedures and compliance checks for an organization to meet program requirements and receive permission to post Checked by NSF signage with a business-specific QR code for transparency to customers. A custom app helps businesses stay organized and track progress.  


The phases

Phase 1 — Plan 

  • Establish foundational protocols and policies with scientific principles established by the World Health Organization, the U.S. Centers for Disease Control and Prevention and other national public health authorities;
  • Develop risk-based (hot-spot) control plans; and
  • Form and train a COVID-19 team of employees.

Phase 2 — Implement 

  • Prepare site to reopen; implement administrative and engineering controls according to the organization’s plan; and
  • Front-line staff has been trained on daily operational checklists and company-specific COVID-19 safety protocols. 

Phase 3 — Improve

  • Maintain program effectiveness through ongoing monitoring and management; and
  • Continuously improve and update organization’s protocols as science evolves, risks change and the program matures.


Additional steps

As buildings reopen, owners should take actions before returning to full service to reduce hazards and control amplification of risks. Some practical steps that can be taken now include:

  • Keep water flowing to reduce water age;
  • Strategically monitor disinfectant residuals;
  • Maintain routine treatment of cooling towers and other aerosol-generating water systems;
  • Control water temperature ranges to reduce amplification of Legionella and other waterborne pathogens (Legionella proliferates at 77° F to 108° F); also identify temperature collection points;
  • Establish water-monitoring strategies (disinfectant residuals, pH, temperature and microbiological analysis);
  • Keep records updated and defensible (verification and validation); and
  • Incorporate water safety into business continuity plans; prior to returning to normal service, prepare a site-specific plan for evaluating and documenting the safety of water systems.

The CDC and multiple state and city agencies have issued guidance and/or requirements for managing risks associated with reduced water utilization due to COVID-19, with a key requirement being the establishment of a water management plan to organize safety efforts. Creating or updating an existing water safety and water management plan is critical to protect the health and safety of employees, tenants and customers.

Plans should describe all water systems within a building, the flow of water, how risks are managed and other necessary building-specific measures. It is important to identify who is responsible and accountable. 

Other important aspects of an effective water management plan include:

  • Pools and other water systems closed for extended periods should follow their plan’s shut-down and start-up procedures. Other systems shut down intermittently should be carefully managed to ensure continued biocide application and water recirculation, so every drop sees every biocide feed. Cooling tower systems not actively managing Legionella growth for five days should be fully cleaned and disinfected. NSF’s protocol (NSF P453) detailing guidance on this is available on request; and
  • Drinking water storage tanks require special attention, and all emergency water systems should be kept operational as usual. Recirculation pumps for hot or cold domestic water systems should also be used to prevent stagnation.

For more information about how NSF’s building water health experts can help minimize risks associated with all water systems, email For additional details about the new Checked by NSF program, contact