The first indicator of dehydration is thirst. Our brains have a thirst center. When one does not drink enough, a mild dehydration occurs, blood pressure decreases, and the thirst center is stimulated. Older adults are more likely to feel this sensation later in life, making them more susceptible to dehydration. If we do not drink enough, we will experience exhaustion, vertigo, and headaches. This might cause disruptions in awareness, decreases in blood pressure, behavioral issues, and extremely black urine after a few days. If the body loses more than 10% of its weight in water (about 4 to 5 liters), life is jeopardized.