Leaking in stainless steel water bottles is often caused by a worn-out gasket, improper lid closure, cross-threading, pressure build-up from hot liquids or carbonation, or manufacturing defects. To prevent leaks, regularly inspect and replace damaged gaskets, ensure lids are properly screwed on, avoid filling bottles with carbonated or very hot drinks, and maintain a high standard of quality control during manufacturing. Additionally, regular cleaning and using appropriate materials for gaskets, like silicone, help maintain a proper seal. Educating users on proper use and care also reduces the risk of leakage.