Although using a toothbrush twice a day has become routine, not everyone agrees on how you should store your toothbrush. Here's why storing your toothbrush outside is the best option. Brushing your teeth will cover your toothbrush bristles with germs and plaque, which must be rinsed away. Some bacteria will linger on your toothbrush no matter how thoroughly you clean it. Covering your toothbrush after cleaning creates a wet environment around the bristles, allowing germs to develop faster than an exposed toothbrush. Open-air drying promotes faster drying and reduced bacterial development, which can help keep your toothbrush clean and useful for a longer period of time.