The bottle may leak from under the locking ring for more than one reason.
To prevent leaks, always make sure you:
- Remove any debris or residue that may collect around the rim of the bottle base or adapter ring before assembly.
- Avoid over-tightening the bottle screw ring when assembling onto the bottle base.
Make sure the adapter ring is inserted and it is properly seated on the bottle. Always assemble nipples and adapter ring when wet.

If you have any continued issues, please contact Customer Service.