Mold removal from mechanical systems
Mechanical systems that require mold removal will need to be shut down immediately to halt contaminants from spreading throughout the building. Any system components that were not exposed to the water intrusion need to be kept dry and be protected against cross contamination from parts contaminated by black or gray water.
Mold removal from HVAC
Solid surface materials can be sprayed with a pressure washer and/or scrubbed with bleach or detergent. Scrub to loosen residual dirt then with a HEPA vacuum completely clean the internal workings and all component of the HVAC system. The Air Conditioning Contractors of America (ACCA) advise that a pressure washer can be used but there can be no wet surfaces left in the HVAC once it has been cleaned. Any porous substances such as fiberglass that has become wet in the air handling system need to be replaced.
Dry filters can be set aside during the cleanup but any filters exposed to water should be discarded. It is important to remember though that the filters must be in place whenever the system is operating. However at no time should the system be in operation if the filters are not in place.
Heating/cooling coils can be sprayed with a pressure washer and scrubbed with detergents.
Mold removal from floor drains
Sumps and floor drains should be flushed for mold removal and disinfected. When flooding occurs water pipes can become contaminated with black water because the water pressure can cause systems to reverse — they need to be disinfected by injecting bleach into the lines.
Mold removal from air-handling units
Air ducts wet by clean water can be used safely provided that they are thoroughly dried in a timely manner. Whenever dirt and water can be seen the entire system should be cleaned. Exposure to black or gray water means that ducts will have to be taken apart to be disinfected, thoroughly dried then reassembled. Do not use biocides on ducts. See mold in ducts.
Air-handling units contaminated by mold or black water should be re-conditioned using a ten percent bleach solution, or removed for decontamination off-site. Fins and coils must be pressure washed. All porous materials must be discarded.
Diffusers, grills and registers that have been in contact with either clean or gray water can be disinfected and dried. Anything in contact with black water or contaminated with mold needs to be removed and cleaned.
The HVAC system should have a system purge before going back into operation. Cover the grills and supply air diffusers with thirty percent or higher efficiency filters, taping edges in place to ensure a complete system purge. Run the system at variable speeds for a few hours to dislodge any remaining debris. Take off the filters and vacuum the filters and grill areas.
Mold Removal from electrical appliances, light fixtures and circuit breakers
Wherever flood water is present power needs to be turned off at the circuit panel before any appliances or electrical components can be removed. Electrical components should be inspected and fixed by a qualified electrician.
Anything soaked in black water should be considered unsalvageable. Replace fuses or circuit breakers that have become wet. Outlets and switches can often be rescued after water exposure if they can be effectively cleaned and dried. Light fixtures will have to be opened then cleaned and dried before they can be turned on again. Electric motors and appliances require careful inspection, cleaning and drying. Electronic items don’t generally fare well with water or mold damage though CDs and DVDs can be cleaned with distilled water and dried with lint-free cloth.