As a year long user of the PIS, I can say that I discovered moisture in the tubes only once or twice. I made a habit of letting the pump run with only the tubing attached while I cleaned up. After I put away the milk and made myself 'presentable' then I took the tubes off the pump and put them away. Most of my fellow pumping moms follow the same routine and getting mold in them makes one more conscientious about proper drying techniques. One of my friends told me that she was desperate enough to buy aquarium tubing while waiting for the new tubes to arrive. Jennifer Nursing Mothers' Counselor Harrisburg, PA