Listerine mouthwash says "Do not eat or drink within 30 minutes of using", however I always rinse after using it. Is it harmful to drink water?

Mouthwash. The best time to use a mouthwash is probably before bedtime since the residue of the mouthrinse may remain in the mouth for a longer period of time and have a greater effect. Rinsing with water would only dilute the mouthwash. .