Emergency Flushing of Building Water Systems

Emergency Flushing

The COVID-19 Pandemic has resulted in some unprecedented actions by local, state and federal governments, including shutting down many non-essential businesses. In recent weeks, the shutdowns have started to expire, and many businesses are reopening their doors to employees, tenants and customers. In addition to ensuring that the workplaces and commercial buildings are clean and safe, the operational systems in place must also be checked and prepared for reopening. Nowhere is this more crucial than the water system. Here at Armstrong Plumbing, Air & Electric, we want to help our commercial customers get back to business as safely as possible, so let’s talk about what you need to do to ensure your water systems and devices are clean and operating efficiently with emergency flushing.


The lockdown of essential businesses and shelter in place orders issued during the pandemic have resulted in the closures of many commercial buildings and business structures. When buildings are shut down for long periods of time, the water in the buildings’ piping systems will lose its water treatment chemicals through oxidation or dissipation. Eventually the levels of these chemicals sink too low to control Legionella bacteria and other microorganism growth; this condition is compounded by stagnant/standing water in the plumbing systems. Legionella bacteria can flourish in stagnant or standing water in a plumbing system, especially when the water temperature dips into the 80-105 degree range.


To ensure that your water system and all accompanying devices are safe and bacteria free, here are some steps to take:

  1. Develop a building water safety plan and water management team to inspect and assess water systems and devices and prevent Legionella. A good resource is: https://www.cdc.gov/legionella/wmp/toolkit/index.html
  2. Inspect your water heater and ensure it is in good working condition. Make sure the temperature is set to a minimum of 140 degrees.
  3. Flush the water system in order to replace all water inside the system’s piping with fresh water. This is done by running hot and cold water through all points of water use, such as sinks, toilets, faucets etc. Regarding hot water, flush until it reaches its maximum temperature.
  4. Other devices such as ice machines and drinking water fountains may need additional cleaning other than flushing. Check instruction manuals for more information.
  5. For all of our hotel/apartment complex/housing customers; ensure spas and hot tubs are safe for use. Here is a good resource for testing: https://www.cdc.gov/legionella/downloads/hot-tub-disinfection.pdf
  6. Inspect, clean and disinfect safety equipment such as sprinkler systems and safety showers.
  7. Maintain and regularly sanitize your system. Once you have reopened the water system and it is operating safely, regularly check for Legionella threat by monitoring water temperature, pH and water treatment chemical levels.


For more information, check out the key points in ASHRAE 188 Standard titled: Legionellosis: Risk Management for Building Water Systems and ASHRAE Guideline 12 -2000: Minimizing the Risk of Legionellosis associated with Building Water Systems. Plus, you can always call your friends here at Armstrong Mechanical and we can help guide you through getting your commercial building reopened safely.