Dehydrated skin will look tight and may have very fine lines over its surface. Should your skin become dehydrated this can usually be quite easily rectified.
Some people confuse dehydrated skin for dry skin. This usually happens when a lack of water causes the skin not to be able to shed naturally and, therefore, build up dead skin cells. This will give a flaking appearance.
Dehydrated skin is usually a result of a lack of water intake. However, if your skin cannot produce enough natural oil, this can compromise its barrier function and allow moisture to escape from the skin. This results in the skin becoming dehydrated.