Yes, the Seresto collar is waterproof and will remain effective even after being submerged in water. The active ingredients are bonded within the collar material itself so they won’t leach out onto your pet or wash away if it gets wet. It’s designed to offer continuous protection for up to eight months as long as the collar remains in good condition, fitting snugly without any damage or breakage. The environmental factors such as these will not lessen its effectiveness.