If the leakage is coming from the reservoir, there are two solutions you can try.
After re-filling water/mouthwash into the reservoir, close reservoir door by pushing in the center of the door. This will ensure that the reservoir door/cover is closed. You should hear a clicking sound.
Too much water/mouthwash
Ensure that you do not put too much water/mouthwash inside the reservoir.
If you overfill the reservoir, and then close the door, the excess water will come out/be released. If this happens, simply wipe the area and handle off with a dry cloth.
If these solutions did not solve the issue, please contact us for further assistance.