Yes, you use it twice a day and it goes in your mouth... and even the cleanest of mouths are loaded in germs and bacteria. However, as long as you’re properly storing your toothbrush, that quick rinse at the end of your brushing is just fine.
Here are the general recommendations for Toothbrush Care from the ADA (American Dental Association) and the Council on Scientific Affairs:
Do not share toothbrushes. Sharing a toothbrush could result in an exchange of body fluids and/or microorganisms between the users of the toothbrush, placing the individuals involved at an increased risk for infections. This practice could be a particular concern for persons with compromised immune systems or existing infectious diseases.
Thoroughly rinse toothbrushes with tap water after brushing to remove any remaining toothpaste and debris. Store the brush in an upright position if possible and allow the toothbrush to air-dry until used again. If more than one brush is stored in the same holder or area, keep the brushes separated to prevent cross-contamination.
Do not routinely cover toothbrushes or store them in closed containers. A moist environment such as a closed container is more conducive to the growth of microorganisms than the open air.
Replace toothbrushes at least every 3–4 months. The bristles become frayed and worn with use and cleaning effectiveness will decrease. Toothbrushes will wear out more rapidly depending on factors unique to each patient. Check brushes often for this type of wear and replace them more frequently if needed. Children’s toothbrushes often need replacing more frequently than adult brushes.
Although studies have shown that various microorganisms can grow on toothbrushes after use, and other studies have examined various methods to reduce the level of these bacteria, there is insufficient clinical evidence to support that bacterial growth on toothbrushes will lead to specific adverse oral or systemic health effects.
If you are interested in reading more on this topic, here is the full article from the ADA: https://www.ada.org/en/about-the-ada/ada-positions-policies-and-statements/statement-on-toothbrush-care-cleaning-storage-and-