Prolonged use of a healthy bottle can lead to slight wear of the flexible O-ring on the bottle cap. The solution is the possibility to order a replacement seal, and thus return ZL to its original functionality.
Instructions for replacing seals in a Healthy Bottle
To remove the old seal in the bottle, repeatedly tap the lid hard on the table, or use a thin tool to pull out the seal. You insert the new seal into the groove using, for example, the inverted end of a coffee spoon, a cutlery knife, etc. You screw in the bottle, the seal "settles" and the healthy bottle is ready for use.