Instruct family members to hang up towels after using them. This gives the towels time to dry out before being put in the hamper. Towels that don't fully air out can quickly grow mold.
Dry your towels thoroughly after laundering. Set the clothes dryer on "hot" to dry a load of towels or hang them up on a clothesline. If the towels are still damp when you fold and store them, mold can grow.
Ventilate the bathroom while taking a shower or a long, hot bath. Use an exhaust fan or a dehumidifier. Both remove excess moisture from the air that may allow mold to grow on the towels and other surfaces. Set the humidifier so it keeps the humidity level at approximately 35 to 50 percent, as researchers at the University of Maryland Medical Center suggest.