Please note mold is not a manufacturing defect and it's common to become an issue when it's not cleaned on a regular basis.
The User Manual for Brusheez states that each brush head should be removed from the handle at least once a week for cleaning and to remove any excess water or residue left from running the toothbrushes under water.
If you have any further questions, please reach out to us by submitting a ticket or calling 1-657-275-3734 Monday through Friday 8 am PST to 5 pm PST.