Our closed system means that the tubing does not need to be washed because the expressed milk does not come into contact with the tubing. If you accidentally wash the tubing, you can disconnect the tubing from the diaphragm cap and run the pump for a few minutes to see if the air from the base eliminates any condensation that may be inside. If you notice any remaining condensation or anything that may be mould, you will need to discard the tubing and contact our customer service team to purchase a new tubing.