You know the laundry list of reasons why you should be drinking more water — it helps flush out toxins, carries important nutrients to the brain, and so on. But it also turns out that keeping your water bottle topped off may help prevent headaches for some people.

But how much H20 should you be consuming? Experts recommend about 13 cups per day for men and about nine for women. That’s not too far off from the conventional wisdom that you should be gulping down eight 8 oz. glasses per day.