18 Things That Happen to Your Body When You Don't Drink Enough Water

Your eyes could swell up
Our eyes are the most liquid-y part of our bodies, so it only stands to reason that dehydration would have a serious effect on them. Doctors have found that in the most seriously dehydrated people, their eyes tend to "sit back" in their heads, causing swelling, which, if it ever happens to you or someone you know, is cause to immediately dial 911 as it's a medical emergency.