Mildew and mold have the same simple requirements for growth: moisture and nourishment. Moisture from leaks or indoor relative humidity levels higher than 55% can support fungal growth. Run a dehumidifier to keep ambient humidity in the 30% to 50% range.
Should any form of water damage occur, property owners should pursue mitigation and restoration in a timely manner. The risk of a mold infestation rises the longer water is left standing and materials stay saturated. Mold may start growing in as little as 48 to 72 hours if moisture levels remain elevated.
While it is not possible to eliminate every source of nourishment, as many building materials and contents are made out of the plant fiber cellulose, it is important to clean and disinfect surfaces on a regular basis. As long as you control moisture levels, fungus growth will be less likely anywhere in a home or commercial building.