Follow these steps to make sure that your Nanobébé bottle does not leak:
Make sure all bottle parts are thoroughly cleaned and dried prior to assembly.
Ensure that the storage cap or nipple are OFF the bottle body prior to attaching it to the base.
Securely press the bottle body onto the base and check to make sure that it is sealed tightly all the way around.
It is crucial to warm your milk with the nipple on, not the storage cap. Warming with the storage cap on can create an air pressure buildup that could lead to a potential opening at the base. The nipple's ventilation will prevent this. Only use warm, never boiling, water.
When attaching the nipple, be sure to align the threading and screw on tightly.
Click here for a step-by-step video.