When cleaning flood contaminated commercial HVAC systems flood (heating, ventilating, and air conditioning) they often take in large amounts of debris, and can even be contaminated with bacteria and mold. Here are some tips to properly clean your commercial systems to ensure customers and employees are comfortable and breath healthy air upon returning to work.

Mold and bacteria can grow on any HVAC surface whether it was submerged under flood waters or not. In addition, these potentially dangerous microorganisms can grow within the ducts and system components themselves due to the large amount of heat and moisture likely to be present. So, all HVAC system components need to be closely inspected and properly cleaned and disinfected before reuse.


  • Zone off occupied areas of the building by using drop cloths, construction plastic, temporary partitions
  • Use blowers with HEPA filters to dry surfaces and improve air qualities within work area. In extreme circumstances it may be necessary to blow non-impacted areas.



  • Workers should use approved respirator to guard airborne contaminants.
  • Verify proper ventilation when using strong disinfectants.
  • Implement a respiratory protection program that meets the requirements of the OSHA respiratory protection standards, as necessary.
  • The minimum requirements for a respiratory protection program include a written standard operating procedure for the following: selecting and using respirators; the medical evaluation of workers to determine whether they are physically able to wear the respirator selected for use; training and instructions on respirator use; the cleaning, repair, and storage of respirators; the continued surveillance of work area conditions for worker exposure and stress; and a respirator fit-testing program.
  • For tight-fitting respirators, fit-testing is necessary to help ensure that the respirator fits tightly, reducing the potential for leakage of outside air from around the edge of the mask. In addition, employers must provide workers with appropriate skin, eye, and hearing protection for the safe performance of their jobs.



  • Remove all contaminated insulation surrounding and within HVAC system components.
  • Discard contaminated materials appropriately following applicable Federal, State, and local regulations.
  • Remove flood-damaged HVAC filters.
  • Clean flood-contaminated HVAC system components with a HEPA-filtered vacuum cleaner to remove debris and mold.
  • Disinfect all HVAC system components using bleach diluted with water.
  • Repeat disinfection procedure with a clean water rinse. Use of a high pressure washer may be needed



  • Replace insulation when HVAC components are disinfected
  • Remove HVAC system fan after it has been disinfected and dried. Needs to be tested by a qualified professional before it is placed back into the air-handling unit
  • Consider upgrading the HVAC system filtration to the highest efficiency filters
  • Hire a qualified professional to evaluate and verify HVAC performance and effectiveness
  • Operate the HVAC system continuously in a normal manner for 48 to 72 hours
  • Check HVAC system frequently to verify it is again working properly