Cacti are distinctive and unusual plants, which are adapted to extremely arid and hot environments, showing a wide range of anatomical and physiological features which conserve water.
Drinking cactus water in its raw form is very health hazardous. It used to be said that cactus juice was safe to drink for people who had to survive in the desert. Unfortunatley, cactus juice is unsafe to drink in its raw form because the juice is actually an acid that keeps creatures from eating the plant out of existance (this would also explain the reasons why the cactus has needles growing out of its plant body). -Wikipedia