Why does dark urine mean your dehydrated?

Dark urine typically indicates dehydration because it results from a higher concentration of waste products and pigments, such as urochrome, that occur when the body lacks sufficient water. When you're dehydrated, your kidneys conserve water by concentrating urine, leading to a darker color. In contrast, well-hydrated individuals tend to have lighter, more diluted urine. Monitoring urine color can be a simple way to assess hydration status.