Aloe Vera gel contains 95% water but it is said to be a desert plant. Why?

Plants in the desert have to cope with very little water so, they carry out some adaptations to survive.

Aloe vera is a stemless or very short-stemmed, perennial succulent xerophyte plant. 

It develops gel in its leaves which serves as the water and energy storage component of the plant, and its leaves are also covered with a thick layer of wax that reduces transpiration and reflects heat.

That's why even being a desert plant, Aloe vera contains 95% of water.

The adaptation explained above helps Aloe vera to survive in dry areas of low or irregular rainfall.