While the CDC recommends washing produce like grapes with water before consuming, you should be washing them in something else to fully break down potential pesticides.
In a 2017 study, a solution made with baking soda removed more pesticide residue from the surface of an apple's skin than either Clorox bleach or regular tap water.
To wash grapes with baking soda, add one teaspoon of salt and baking soda to a bowl of water. Add your rinsed grapes and gently swoosh and rub them for a minute before rinsing.
Alternatively, you can add two tablespoons each of vinegar and baking soda to a bowl of water, then add the grapes, massage them, and soak for up to 15 minutes before rinsing.