Common misconception. Diuretics simply cause you to urinate more often. It does not necessarily mean you will urinate more than the water you are taking in. Coffee also falls into this category. The most known “don’t drink this or you’ll dehydrate” salt water will cause you to urinate more than the water you take in. Salt water is about 3.5% salt. Your kidneys can only function up to like 2%. This makes your body pull water from elsewhere to flush the excess salt out of your system.