Tuaregs are immune, they can drink directly. We, city people, need to add purification tablets. A guelta is a natural tank, not a well, so the water is stagnant. But they are well protected so people and animals only drink, not bathe in them. Especially bad behaving tourists with shampoos and shower gels!

Date shot: February 25, 2008
Location: the area of Ahnet, Algerian Sahara
Camera Nikon D200, lens Nikkor VR 18-200mm
Fl 135mm, F11, 1/160s
ISO 100, WB auto, Mode Shutter Priority