Hello Muhammad, I would ...

Hello Muhammad, I would suggest a Multiple-effect distillation (MED) system powered by Solar such as Focal Line Solar, to achieve a high quality potable water at the least expensive possible cost.  The short video is a proposal from Focal Line Solar to supply potable water and electricity for the Trans Africa Pipeline (TAP).  A similar setup would work well for you.  TAP will provide fresh water for drinking and irrigation across an 8000 kilometer strip of land just south of the Sahara and also provide water to refill Lake Chad.  Please be welcome to contact me for more information.