Empty the bottle and find the gasket
Remove the cap and check whether the silicone ring is seated flat in its groove. A stretched, torn, or missing gasket should be replaced with the correct part rather than compensated for by overtightening the cap.
Clean the threads and valve path
Sand, fur, and food residue can interrupt a seal. Wash parts according to the manufacturer's directions and rinse thoroughly. Do not poke a valve with a sharp object because that can damage the sealing surface.
Leak-test it over a sink
Fill the bottle halfway, close it with normal hand pressure, engage its lock, and tilt it in several directions over a sink. If droplets continue to form around the valve or cap, carry water in another sound container until the bottle is repaired or replaced.
Make replacement parts part of the buying decision
Capacity matters less if a tiny seal cannot be cleaned or replaced. Check whether the gasket and valve can dry separately and whether model-specific parts are sold before buying a large bottle for frequent walks.
When a product change is not the first step
Small gaskets and valve pieces can be swallowing hazards. Keep loose parts away from pets, and contact a veterinarian if a missing piece may have been swallowed.
Product comparison note
What to compare if equipment may help
Look for a bottle with removable washable seals, a lock that cannot be bumped easily inside a bag, and replacement parts available for the exact model.
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