To a 8-ounce bottle or larger (I purchase my bottles from HomeGoods or Target, check the kitchen gadget aisle), add all the ingredients: aloe vera, water, baking soda, peppermint essential oil, and tea tree oil.
Seal the bottle and shake to combine the ingredients. The baking soda should dissolve after just a few shakes. Store the mouthwash in the fridge between uses.