In a pump bottle mix together some vodka (doesn't matter what kind), water (I use distilled or purified) and baking soda. You can also add vinegar to the mixture, it'll foam a bit though so make sure the bottle isn't full when you do. I don't measure anything but I do add more water than anything else. I also add essential oils but they are expensive. Antibacterial oils are Lemon, Lavender, Rosemary, Eucalyptus, Tea Tree. I add em all! The baking soda is what should really make the grout sparkle. The first time you may have to scrub but after that just spray weekly.